methyl-jasmonate and jasmonic-acid

Exposure of crops to low temperature (LT) during emerging and reproductive stages influences their growth and development. In this study, we have isolated a cold induced, nucleus-localized lipid A gene from rice named OsLPXC, which encodes a protein of 321 amino acids. Knockout of OsLPXC resulted in enhance sensitivity to LT stress in rice, with increased accumulation of reactive oxygen species (ROS), malondialdehyde and electrolyte leakage, while expression and activities of antioxidant enzymes were significantly suppressed. The accumulation of chlorophyll content and net photosynthetic rate of knockout plants were also decreased compared with WT under LT stress. The functional analysis of differentially expressed genes (DEGs), showed that numerous genes associated with antioxidant defense, photosynthesis, cold signaling were solely expressed and downregulated in oslpxc plants compared with WT under LT. The accumulation of methyl jasmonate (MeJA) in leave and several DEGs related to the jasmonate biosynthesis pathway were significantly downregulated in OsLPXC knockout plants, which showed differential levels of MeJA regulation in WT and knockout plants in response to cold stress. These results indicated that OsLPXC positively regulates cold tolerance in rice via stabilizing the expression and activities of ROS scavenging enzymes, photosynthetic apparatus, cold signaling genes, and jasmonate biosynthesis.

Topics: Antioxidants; Cold Temperature; Cold-Shock Response; Gene Expression Regulation, Plant; Oryza; Oxidative Stress; Reactive Oxygen Species

Recently, plant secondary metabolites are considered as important sources of pharmaceuticals, food additives, flavours, cosmetics, and other industrial products. The accumulation of secondary metabolites in plant cell and organ cultures often occurs when cultures are subjected to varied kinds of stresses including elicitors or signal molecules. Application of exogenous jasmonic acid (JA) and methyl jasmonate (MJ) is responsible for the induction of reactive oxygen species (ROS) and subsequent defence mechanisms in cultured cells and organs. It is also responsible for the induction of signal transduction, the expression of many defence genes followed by the accumulation of secondary metabolites. In this review, the application of exogenous MJ elicitation strategies on the induction of defence mechanism and secondary metabolite accumulation in cell and organ cultures is introduced and discussed. The information presented here is useful for efficient large-scale production of plant secondary metabolites by the plant cell and organ cultures.

Topics: Acetates; Cells, Cultured; Cyclopentanes; Oxidative Stress; Oxylipins; Plant Cells; Plant Growth Regulators; Plants; Reactive Oxygen Species; Signal Transduction

Jasmonates (JAs) are physiologically important molecules involved in a wide range of plant responses from growth, flowering, senescence to defence against abiotic and biotic stress. They are rapidly synthesised from α-linolenic acid (ALA; C18:3 ∆9,12,15) by a process of oxidation, cyclisation and acyl chain shortening involving co-operation between the chloroplast and peroxisome. The active form of JA is the isoleucine conjugate, JA-isoleucine (JA-Ile), which is synthesised in the cytoplasm. Other active metabolites of JA include the airborne signalling molecules, methyl JA (Me-JA) and cis-jasmone (CJ), which act as inter-plant signalling molecules activating defensive genes encoding proteins and secondary compounds such as anthocyanins and alkaloids. One of the key defensive metabolites in many plants is a protease inhibitor that inactivates the protein digestive capabilities of insects, thereby, reducing their growth. The receptor for JA-Ile is a ubiquitin ligase termed as SCFCoi1 that targets the repressor protein JA Zim domain (JAZ) for degradation in the 26S proteasome. Removal of JAZ allows other transcription factors (TFs) to activate the JA response. The levels of JA-Ile are controlled through catabolism by hydroxylating enzymes of the cytochrome P450 (CYP) family. The JAZ proteins act as metabolic hubs and play key roles in cross-talk with other phytohormone signalling pathways in co-ordinating genome-wide responses. Specific subsets of JAZ proteins are involved in regulating different response outcomes such as growth inhibition versus biotic stress responses. Understanding the molecular circuits that control plant responses to pests and pathogens is a necessary pre-requisite to engineering plants with enhanced resilience to biotic challenges for improved agricultural yields.

Topics: Acetates; Chloroplasts; Cyclopentanes; Gene Expression Regulation, Plant; Isoleucine; Oxylipins; Plant Growth Regulators; Plants; Signal Transduction; Transcription Factors; Ubiquitin-Protein Ligases

Since salicylate, a plant stress hormone, suppresses the growth of various types of cancer cells, it was deemed of interest to investigate whether the jasmonate family of plant stress hormones is endowed with anti-cancer activities. Cell lines representing a wide spectrum of malignancies, including prostate, breast and lung, exhibit sensitivity to the cytotoxic effects of methyl jasmonate (MJ). Jasmonates induced death in leukemic cells isolated from the blood of chronic lymphocytic leukemia (CLL) patients and increased significantly the survival of lymphoma-bearing mice. Among the naturally occurring jasmonates, MJ is the most active, while the synthetic methyl-4,5-didehydrojasmonate, was approximately 29-fold more active than MJ. The cytotoxic activity of MJ is independent of transcription and translation. Studies have suggested several mechanisms of action. It appears that while prolonged exposures to relatively low concentrations of jasmonates induce growth arrest and re-differentiation in myeloid leukemia cells, higher concentrations of MJ induce direct perturbation of cancer cell mitochondria, leading to the release of cytochrome c and eventual cell death. A most important characteristic of jasmonates is their ability to selectively kill cancer cells while sparing normal cells. Even within a mixed population of normal and leukemic cells derived from the blood of CLL patients, MJ killed preferentially the leukemic cells. In conclusion, jasmonates present a unique class of anti-cancer compounds which deserves continued research at the basic and pharmaceutical levels in order to yield novel chemotherapeutic agents against a range of neoplastic diseases.

Topics: Acetates; Animals; Antineoplastic Agents; Cell Proliferation; Cell Survival; Cyclopentanes; Humans; Mitochondria; Molecular Structure; Neoplasms; Oxylipins; Plant Growth Regulators

Plants possess an interrelated and interacting family of potent fatty acid-derived regulators--the jasmonates. These compounds, which play roles in both defense and development, are derived from tri-unsaturated fatty acids [alpha-linolenic acid (18:3) or 7Z,10Z,13Z-hexadecatrienoic acid (16:3)]. The lipoxygenase-catalyzed addition of molecular oxygen to alpha-linolenic acid initiates jasmonate synthesis by providing a 13-hydroperoxide substrate for the formation of an unstable allene oxide that is then subject to enzyme-guided cyclization to produce 12-oxo-phytodienoic acid (OPDA). OPDA, a key regulatory lipid in the plant immune system, has several fates, including esterification into plastid lipids or transformation into the 12-carbon co-regulator jasmonic acid (JA). JA, the best-characterized member of the family, regulates both male and female fertility (depending on the plant species), and is an important mediator of defense gene expresssion. JA is itself a substrate for further diverse modifications. Genetic dissection of the pathway is revealing how the different jasmonates modulate different physiological processes. Each new family member that is discovered provides another key to understanding the fine control of gene expression in immune responses, in the initiation and maintenance of long-distance signal transfer in response to wounding, and in the regulation of fertility, among other processes. The Jasmonate Biochemical Pathway provides an overview of the growing jasmonate family, and new members will be included in future versions of the Connections Map. Science Viewpoint R. Liechti, E. E. Farmer, The jasmonate pathway. Science 296, 1649-1650 (2002). [Abstract] [Full Text]

Topics: Acetates; Arabidopsis; Cyclopentanes; Oxylipins; Signal Transduction

Plants synthesize many fatty acid derivatives, several of which play important regulatory roles. Jasmonates are the best characterized examples. Jasmonate-insensitive mutants and mutants with a constitutive jasmonate response have given us new insights into jasmonate signalling. The jasmonate biosynthesis mutant opr3 allowed the dissection of cyclopentanone and cyclopentenone signalling, thus defining specific roles for these molecules. Jasmonate signalling is a complex network of individual signals and recent findings on specific activities of methyl jasmonate and (Z)-jasmone add to this picture. In addition, there are keto, hydroxy and hydroperoxy fatty acids that might be involved in cell death and the expression of stress-related genes. Finally, there are bruchins and volicitin, signal molecules from insects that are perceived by plants in the picomole to femtomole range. They highlight the importance of fatty acid-derived molecules in interspecies communication and in plant defence.

Topics: Acetates; alpha-Linolenic Acid; Animals; Arabidopsis; Arabidopsis Proteins; Chloroplasts; Cyclopentanes; Fatty Acids; Fatty Acids, Volatile; Glutamine; Lipid Peroxides; Lipoxygenase; Models, Chemical; Mutation; Oxidoreductases; Oxylipins; Peroxisomes; Plant Proteins; Signal Transduction

Topics: Acetates; Arabidopsis; Cyclopentanes; Gene Expression Regulation, Plant; Immunity, Innate; Intramolecular Oxidoreductases; Lipoxygenase; Methylation; Models, Chemical; Mutation; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Oxylipins; Signal Transduction

During the past decade there has been rapidly increasing interest in the role of plant volatiles in insect-plant interactions and the induction of plant defence systems by both pathogens and herbivores. Scientists are striving to link the proximate studies elucidating pathways and genes with the ultimate adaptive studies that attempt to explain their ecological role. However, we still do not know whether plants 'talk' to one another by employing 'phytopheromones'.

Topics: Acetates; Adaptation, Physiological; Animals; Cyclopentanes; Genes, Plant; Insecta; Oxylipins; Pheromones; Plants; Signal Transduction

Topics: Acetates; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Oxylipins; Photosynthesis; Plants; Promoter Regions, Genetic; Trans-Activators; Transcription, Genetic

Topics: Acetates; Cyclopentanes; Ethylenes; Immunity, Innate; Oxylipins; Peptides; Plant Growth Regulators; Plant Proteins; Plants; Salicylates; Salicylic Acid; Signal Transduction

Drought, which directly affects the yield of crops and trees, is a natural stress with a profound impact on the economy. Improving water use efficiency (WUE) and drought tolerance are relatively effective strategies to alleviate drought stress. OPEN STOMATA1 (OST1), at the core of abscisic acid (ABA) signaling, can improve WUE by regulating stomatal closure and photosynthesis. Methyl jasmonate (MeJA) and ABA crosstalk is considered to be involved in the response to drought stress, but the detailed molecular mechanism is insufficiently known. Here, Populus euphratica, which naturally grows in arid and semiarid regions, was selected as the species for studying MeJA and ABA crosstalk under drought. A yeast two-hybrid assay was performed using PeOST1 as bait and a nucleus-localized factor, JASMONATE ZIM-domain protein 2 (PeJAZ2), was found to participate in MeJA signaling by interacting with PeOST1. Overexpression of PeJAZ2 in poplar notably increased water deficit tolerance and WUE in both severe and mild drought stress by regulating ABA signaling rather than ABA synthesis. Furthermore, a PeJAZ2 overexpression line was shown to have greater ABA-induced stomatal closure and hydrogen peroxide (H2O2) production. Collectively, this evidence establishes a mechanism in which PeJAZ2 acts as a positive regulator in response to drought stress via ABA-induced stomatal closure caused by H2O2 production. Our study presents a new insight into the crosstalk of ABA and jasmonic acid signaling in regulating WUE and drought stress, providing a basis of the drought tolerance mechanism of P. euphratica.

Topics: Abscisic Acid; Drought Resistance; Droughts; Hydrogen Peroxide; Plant Stomata; Populus; Water

Dandelion is a well-known traditional medical herb, also used as functional food. Dandelion possesses many medical properties, such as anti-bacterial and antioxidant activity and contains a variety of triterpenes, such as α-amyrin, β-amyrin, taraxerol and taraxasterol. In this study, we found that triterpenes biosynthesis was promoted by methyl jasmonate (MeJA), while the transcriptional mechanism underlying triterpenes biosynthesis was rarely investigated. Here, a MeJA-induced bHLH transcription factor TaMYC2 was identified. The content of taraxasterol and taraxerol in dandelion was obviously enhanced in overexpression TaMYC2 transgenic lines and expression level of the squalene synthase gene (TaSS) was elevated to about 3-5 folds compared with the control lines. Dual-LUC, Y1H and EMSA experiments revealed that TaMYC2 bound to the E-box motif in the promoter of TaSS and activated its transcription. Taken together, this study suggested that TaMYC2 acted as a positive regulator for bioengineering approaches to produce high content triterpenes-producing dandelions.

Topics: Basic Helix-Loop-Helix Transcription Factors; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Taraxacum; Triterpenes

Methyl jasmonate (MeJA) induces various defence responses in seed plants, but for early plant lineages, information on the potential of jasmonates to elicit stress signalling and trigger physiological modifications is limited. The spikemoss Selaginella martensii was exposed to a range of MeJA concentrations (0, 10, 25, and 50 mM), and biogenic volatile organic compound (BVOC) emissions, photosynthetic rate (A), and stomatal conductance (gs) were continuously measured. In addition, changes in phytohormone concentrations and gene expression were studied. Enhancement of methanol, lipoxygenase pathway volatiles and linalool emissions, and reductions in A and gs, were MeJA dose-dependent. Before MeJA treatment, the concentration of 12-oxo-phytodienoic acid (OPDA) was 7-fold higher than jasmonic acid (JA). MeJA treatment rapidly increased OPDA and JA concentrations (within 30 min), with the latter more responsive. Some genes involved in BVOC biosynthesis and OPDA-specific response were up-regulated at 30 min after MeJA spraying, whereas those in the JA signalling pathway were not affected. Although JA was synthesized in S. martensii, OPDA was prioritized as a signalling molecule upon MeJA application. MeJA inhibited primary and enhanced secondary metabolism; we propose that fast-emitted linalool could serve as a marker of elicitation of stress-induced metabolism in lycophytes.

Topics: Acetates; Cyclopentanes; Oxylipins; Plant Growth Regulators; Selaginellaceae; Transcriptome

Jasmonic acid (JA) regulates plant growth, development and stress responses. Coronatine insensitive 1 (COI1) and jasmonate zinc-finger inflorescence meristem-domain (JAZ) proteins form a receptor complex for jasmonoyl-l-isoleucine, a biologically active form of JA. Three COIs (OsCOI1a, OsCOI1b and OsCOI2) are encoded in the rice genome. In the present study, we generated mutants for each rice COI gene using genome editing to reveal the physiological functions of the three rice COIs. The oscoi2 mutants, but not the oscoi1a and oscoi1b mutants, exhibited severely low fertility, indicating the crucial role of OsCOI2 in rice fertility. Transcriptomic analysis revealed that the transcriptional changes after methyl jasmonate (MeJA) treatment were moderate in the leaves of oscoi2 mutants compared to those in the wild type or oscoi1a and oscoi1b mutants. MeJA-induced chlorophyll degradation and accumulation of antimicrobial secondary metabolites were suppressed in oscoi2 mutants. These results indicate that OsCOI2 plays a central role in JA response in rice leaves. In contrast, the assessment of growth inhibition upon exogenous application of JA to seedlings of each mutant revealed that rice COIs are redundantly involved in shoot growth, whereas OsCOI2 plays a primary role in root growth. In addition, a co-immunoprecipitation assay showed that OsJAZ2 and OsJAZ5 containing divergent Jas motifs physically interacted only with OsCOI2, whereas OsJAZ4 with a canonical Jas motif interacts with all three rice COIs. The present study demonstrated the functional diversity of rice COIs, thereby providing clues to the mechanisms regulating the various physiological functions of JA.

Topics: Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Gene Editing; Gene Expression Regulation, Plant; Oryza; Oxylipins

Carotenoids are natural pigments that influence the color of citrus fruit. The red-colored carotenoid β-citraurin is responsible for the peel color in "Newhall" orange (Citrus sinensis). Although jasmonates are known to regulate the biosynthesis and accumulation of carotenoids, their effects on β-citraurin biosynthesis in citrus fruit remain unclear. Here, we determined that treatment with methyl jasmonate (MeJA) significantly promotes fruit coloration and β-citraurin production in "Newhall" orange. A MeJA treatment induced the expression of CsMYC2, which encodes a transcription factor that serves as a master regulator of jasmonate responses. CsMYC2 bound the promoter of the gene that encodes carotenoid cleavage dioxygenase 4b (CsCCD4b), the key gene for β-citraurin biosynthesis, and the promoters of genes that encode phytoene synthase (CsPSY), lycopene β-cyclase (CsLCYb), and β-carotene hydroxylase (CsBCH) and induced their expression. In addition, CsMYC2 promoted CsMPK6 expression. Notably, we found that CsMPK6 interacted with CsMYC2 and that this interaction decreased the stability and DNA-binding activity of CsMYC2. Thus, we conclude that negative feedback regulation attenuates JA signaling during the jasmonate-induced coloration of citrus fruit. Together, our findings indicate that jasmonates induce β-citraurin biosynthesis in citrus by activating a CsMPK6-CsMYC2 cascade, thereby affecting fruit coloration.

Topics: Carotenoids; Citrus; Citrus sinensis; Fruit; Gene Expression Regulation, Plant; Geranylgeranyl-Diphosphate Geranylgeranyltransferase

Sheath blight disease of rice caused by a soil-borne fungal pathogen Rhizoctonia solani AG1-IA is one of the major threats to rice production globally. During host-pathogen interactions, reactive oxygen species (ROS) play an important role in pathogen virulence and plant defense. For example, necrotrophic pathogens induce ROS production to damage host cells, whereas the host can incite ROS to kill the pathogen. From the host perspective, it is essential to understand how the antioxidant machinery maintains a delicate balance of ROS to protect itself from its lethal effects. Here, we investigated the pathogen-induced accumulation of ROS and implicated damage in two rice genotypes (PR114, susceptible; ShB, moderately tolerant) varying in the level of susceptibility to R. solani AG1-IA. Compared to PR114, ShB exhibited a better antioxidant response and reasonably lesser oxidative damage. Further, we observed elevated levels of jasmonic acid (JA) in ShB, which was otherwise decreased in PR114 in response to pathogen infection. As depicted, an elevated level of JA was in agreement with the expression profiles of genes involved in its biosynthesis and signaling. To further ascertain if the heightened antioxidant response is JA-dependent or independent, methyl jasmonate (MeJA) was exogenously applied to PR114, and antioxidant response in terms of gene expression, enzyme activities, and oxidative damage was studied in R. solani infected samples. Surprisingly, the exogenous application of MeJA complemented the antioxidant response and reduced oxidative damage in PR114, thus suggesting that the antioxidant defense system is under transcriptional control of JA.

Topics: Antioxidants; Homeostasis; Oryza; Plant Diseases; Reactive Oxygen Species

The low amount of metabolites isolated from natural products is one of the challenges preventing their biological evaluation. The modulation of biosynthetic pathways by stimulating stress-induced responses in plants was proven to be a valuable tool for diversification of already known natural products. Recently, we reported the dramatic effect of methyl jasmonate (MeJA) on

Topics: Alkaloids; Molecular Docking Simulation; TOR Serine-Threonine Kinases; Vinca

5-Aminolevulinic acid (ALA) is a natural and environmentally benign multifunctional plant growth regulator involved in the regulation of plant tolerance to various environmental stresses. This research aimed to explore the molecular mechanisms of salt tolerance in Populus wutunensis induced by exogenous ALA using physiological and transcriptomic analyses.. 5-aminolevulinic acid improved the protein-folding efficiency in the endoplasmic reticulum and the flavonoid-accumulation through the MeJA-activated jasmonic acid signaling, thereby increased salt-tolerance in P. wutunensis.

Topics: Aminolevulinic Acid; Chromatography, Liquid; Flavonoids; Gene Expression Regulation, Plant; Populus; Salt Tolerance; Seedlings; Tandem Mass Spectrometry

The cytochrome P450 superfamily of monooxygenases plays a major role in the evolution and diversification of plant natural products. The function of cytochrome P450s in physiological adaptability, secondary metabolism, and xenobiotic detoxification has been studied extensively in numerous plant species. However, their underlying regulatory mechanism in safflower still remained unclear. In this study, we aimed to elucidate the functional role of a putative CtCYP82G24-encoding gene in safflower, which suggests crucial insights into the regulation of methyl jasmonate-induced flavonoid accumulation in transgenic plants. The results showed that methyl jasmonate (MeJA) was associated with a progressive upregulation of CtCYP82G24 expression in safflower among other treatment conditions including light, dark, and polyethylene glycol (PEG). In addition, transgenic plants overexpressing CtCYP82G24 demonstrated increased expression level of other key flavonoid biosynthetic genes, such as AtDFR, AtANS, and AtFLS, and higher content of flavonoid and anthocyanin accumulation when compared with wild-type and mutant plants. Under exogenous MeJA treatment, the CtCYP82G24 transgenic overexpressed lines showed a significant spike in flavonoid and anthocyanin content compared with wild-type and mutant plants. Moreover, the virus-induced gene silencing (VIGS) assay of CtCYP82G24 in safflower leaves exhibited decreased flavonoid and anthocyanin accumulation and reduced expression of key flavonoid biosynthetic genes, suggesting a possible coordination between transcriptional regulation of CtCYP82G24 and flavonoid accumulation. Together, our findings confirmed the likely role of CtCYP82G24 during MeJA-induced flavonoid accumulation in safflower.

Topics: Anthocyanins; Carthamus tinctorius; Cytochrome P-450 Enzyme System; Flavonoids; Gene Expression Regulation, Plant

Volatile esters in apple (Malus domestica) fruit are the critical aroma components determining apple flavor quality. While the exact molecular regulatory mechanism remains unknown, jasmonic acid (JA) plays a crucial role in stimulating the synthesis of ester aromas in apples. In our study, we investigated the effects of methyl jasmonate (MeJA) on the production of ester aroma in apples. MeJA treatment significantly increased ester aroma synthesis, accompanied by the upregulation of several genes involved in the jasmonate pathway transduction. Specifically, expression of the gene MdMYC2, which encodes a transcription factor associated with the jasmonate pathway, and the R2R3-MYB transcription factor gene MdMYB85 increased upon MeJA treatment. Furthermore, the essential gene ALCOHOL ACYLTRANSFERASE 1 (MdAAT1), encoding an enzyme responsible for ester aroma synthesis, showed increased expression levels as well. Our investigation revealed that MdMYC2 and MdMYB85 directly interacted with the promoter region of MdAAT1, thereby enhancing its transcriptional activity. In addition, MdMYC2 and MdMYB85 directly bind their promoters and activate transcription. Notably, the interaction between MdMYC2 and MdMYB85 proteins further amplified the regulatory effect of MdMYB85 on MdMYC2 and MdAAT1, as well as that of MdMYC2 on MdMYB85 and MdAAT1. Collectively, our findings elucidate the role of the gene module consisting of MdMYC2, MdMYB85, and MdAAT1 in mediating the effects of JA and promoting ester aroma synthesis in apples.

Topics: Esters; Fruit; Gene Expression Regulation, Plant; Malus; Odorants; Plant Proteins; Transcription Factors

Topics: Arsenic; Carbohydrate Metabolism; Ethylenes; Homeostasis; Oryza

Apolygus lucorum (Hemiptera, Insecta), cosmopolitan true bug, is a major pest of the Chinese jujube (Ziziphus jujuba). To propose control measures of A. lucorum, we investigated the molecular mechanisms of resistance in two varieties of jujube (wild jujube and winter jujube) with different sensitivities to this pest. We monitored changes of two species of jujube in the transcriptome, jasmonic acid (JA) and salicylic acid (SA) content, and the expression of genes involved in signaling pathways. The preference of A. lucorum for jujube with exogenous SA and methyl jasmonate (MeJA) were also examined. The results showed that wild jujube leaves infested by A. lucorum showed stronger resistance and non-selectivity to A. lucorum than winter jujube. By comparing data from the A. lucorum infested plants with the control, A total of 438 and 796 differentially expressed genes (DEGs) were found in winter and wild jujube leaves, respectively. GO analysis revealed that biological process termed "plant-pathogen interactions", "plant hormone transduction" and "phenylpropanoid biosynthesis". Most of DEGs enriched in JA pathways were upregulated, while most DEGs of SA pathways were downregulated. A. lucorum increased the JA content but decreased the SA content in jujube. Consistently, the JA and SA contents in winter jujube were lower than those in wild jujube leaves. The key genes ZjFAD3, ZjLOX, ZjAOS, ZjAOC3 and ZjAOC4 involved in JA synthesis of jujube leaves were significantly up-regulated after A. lucorum infestation, especially the expression and up-regulation ratio of ZjFAD3, ZjLOX and ZjAOS in wild jujube were significantly higher than those in winter jujube. MeJA-treated jujube showed an obvious repellent effect on A. lucorum. Based on these findings, we conclude that A. lucorum infestation of jujube induced the JA pathway and suppressed the SA pathway. In jujube leaves the ZjFAD3, ZjLOX and ZjAOS played important roles in increasing of JA content in jujube leaves. Thus, JA played an important role in repelling and resisting against A. lucorum in jujube.

Topics: Animals; Gene Expression Regulation, Plant; Heteroptera; Insecta; Salicylic Acid; Signal Transduction; Ziziphus

Catharanthus roseus (L.) G. Donis a medicinal plant species belonging to the Apocynaceae family, which produces vinblastine and vincristine along with 100 other monoterpenoid indole alkaloids. The process of biosynthesis of C. roseus alkaloids is complex, in which many genes, enzymes, and regulators are involved. Induced mutations may be considered as a potential source for producing a higher amount of vinblastine and vincristine in this plant species. Therefore, the objective of the present study was to examine the effects of different treatments utilized on the induced genetic changes in C. roseus plants and enzyme activities.. Spermine, jasmonic acid, methyjasmonate, putrescine, and cold plasma treatments were used for seed treatments. Different molecular markers, namely inter simple sequence repeat, inter retrotransposon amplified polymorphism, and retrotransposon microsatellite amplified polymorphism were employed to reveal the induced genetic changes. Antioxidant enzyme activities were also studied. The treated plants showed genetic variability and a significant increase in antioxidant enzyme activity compared to the control plants. The putrescine treatment resulted in the highest level of activity in superoxidase. A significant positive correlation occurred between the molecular markers data and antioxidant enzyme activities in treated plants.. Our data revealed that the different phytohormones and cold plasma treatments could induce both genetic and chemical content changes in C. roseus plants.

Topics: Acetates; Catharanthus; Cyclopentanes; Gene Expression Regulation, Plant; Microsatellite Repeats; Oxylipins; Plant Growth Regulators; Plant Proteins; Plants, Medicinal; Plasma Gases; Putrescine; Retroelements; Seeds; Spermine; Superoxide Dismutase

Plant hormones regulate growth, development, and defense against biotic and abiotic stresses. Salicylic acid (SA), ethylene (ET), and jasmonate (JA) are major phytohormones that control the defense against pathogens. SA and JA primarily regulate resistance against biotrophic and necrotrophic pathogens, respectively. NPR1 is the key regulator of SA signaling in plants. AtOZF1 function has recently been ascribed to promote both NPR1- dependent and -independent SA signaling. However, the role of AtOZF1 in JA signaling was not known. Here we report AtOZF1 as a positive regulator of JA signaling in Arabidopsis. The

Topics: Acetates; Antimicrobial Cationic Peptides; Arabidopsis; Arabidopsis Proteins; Botrytis; Cyclopentanes; Defensins; Disease Resistance; Gene Expression Regulation, Plant; Membrane Proteins; Mutation; Oxylipins; Plant Diseases; Plant Growth Regulators; Salicylic Acid; Signal Transduction

The application of methyl jasmonate (MeJ) as an elicitor to enhance secondary metabolites in grapes and wines has been studied, but there is little information about its use in conjunction with nanotechnology and no information about its effects on wine volatile compounds. This led us to study the impact of nanoparticles doped with MeJ (Nano-MeJ, 1mM MeJ) on the volatile composition of Monastrell wines over three seasons, compared with the application of MeJ in a conventional way (10 mM MeJ). The results showed how both treatments enhanced fruity esters in wines regardless of the vintage year, although the increase was more evident when grapes were less ripe. These treatments also achieved these results in 2019 in the cases of 1-propanol, ß-phenyl-ethanol, and methionol, in 2020 in the cases of hexanol and methionol, and in 2021, but only in the case of hexanol. On the other hand, MeJ treatment also increased the terpene fraction, whereas Nano-MeJ, at the applied concentration, did not increase it in any of the seasons. In summary, although not all families of volatile compounds were increased by Nano-MeJ, the Nano-MeJ treatment generally increased the volatile composition to an extent similar to that obtained with MeJ used in a conventional way, but at a 10 times lower dose. Therefore, the use of nanotechnology could be a good option for improving the quality of wines from an aromatic point of view, while reducing the necessary dosage of agrochemicals, in line with more sustainable agricultural practices.

Topics: Acetates; Cyclopentanes; Fruit; Hexanols; Odorants; Oxylipins; Vitis; Volatile Organic Compounds; Wine

The western flower thrips,

Topics: Acetates; Animals; Cyclopentanes; Flavonoids; Flowers; Glutathione Transferase; Lignin; Oxylipins; Phaseolus; Phenols; RNA Interference; Tannins; Thysanoptera

Alkannin/shikonin and their derivatives are specialised metabolites of high pharmaceutical and ecological importance exclusively produced in the periderm of members of the plant family Boraginaceae. Previous studies have shown that their biosynthesis is induced in response to methyl jasmonate but not salicylic acid, two phytohormones that play important roles in plant defence. However, mechanistic understanding of induction and non-induction remains largely unknown. In the present study, we generated the first comprehensive transcriptomic dataset and metabolite profiles of Lithospermum officinale plants treated with methyl jasmonate and salicylic acid to shed light on the underlying mechanisms. Our results highlight the diverse biological processes activated by both phytohormones and reveal the important regulatory role of the mevalonate pathway in alkannin/shikonin biosynthesis in L. officinale. Furthermore, by modelling a coexpression network, we uncovered structural and novel regulatory candidate genes connected to alkannin/shikonin biosynthesis. Besides providing new mechanistic insights into alkannin/shikonin biosynthesis, the generated methyl jasmonate and salicylic acid elicited expression profiles together with the coexpression networks serve as important functional genomic resources for the scientific community aiming at deepening the understanding of alkannin/shikonin biosynthesis.

Topics: Acetates; Cyclopentanes; Lithospermum; Mevalonic Acid; Naphthoquinones; Oxylipins; Pharmaceutical Preparations; Plant Growth Regulators; Salicylic Acid

Accumulation of anthocyanins in detached leaves and in excised stems of

Topics: Anthocyanins; Kalanchoe; Lanolin; Plant Leaves

Topics: Acetates; Biomass; Biosynthetic Pathways; Carbohydrates; Cyclopentanes; Hypericum; Ions; Light; Organ Size; Oxylipins; Phenols; Pigments, Biological; Plant Exudates; Plant Leaves; Plant Roots

Among rare earth elements, cerium has the unique ability of regulating the growth of plant cells and the biosynthesis of metabolites at different stages of plant development. The signal pathways of Ce

Topics: Acetates; Cerium; Cyclopentanes; Ginsenosides; Oxylipins; Panax; Plant Proteins; Plant Roots; Reactive Oxygen Species; Signal Transduction

Here, we reported that a pathogen- and herbivore-induced Kunitz trypsin inhibitor gene, NaKTI2, is required for herbivore resistance, and transcriptionally regulated mainly by NaWRKY3 and NaWRKY6 but not Jasmonate signaling. Plant protease inhibitor (PI) occurs widely in plant species, and is considered as an important part of plant defense arsenal against herbivores. Transcriptome analysis of Nicotiana attenuata leaves revealed that a Kunitz trypsin inhibitor gene, NaKTI2, was highly elicited after inoculation of Alternaria alternata (tobacco pathotype). However, the roles of NaKTI2 in pathogen- and herbivore resistance and its regulation were unclear. NaKTI2 had typical domains of Kunitz trypsin inhibitors and exhibited a high level of trypsin protease inhibitor activities when transiently over-expressed. The transcripts of NaKTI2 could be induced by A. alternata and Spodoptera litura oral secretions (OS). Silencing NaKTI2 via virus-induced gene silencing technique has no influence on lesion diameters developed on N. attenuata leaves after A. alternata inoculation, but S. litura larvae gained more mass and had higher survivorship on NaKTI2-silenced plants. Meanwhile, the expression of NaPI, a PI gene essential for herbivore resistance previously identified in N. attenuata, was not affected in NaKTI2-silenced plants. Unlike NaPI, which was predominantly regulated by jasmonate (JA) signaling, OS-elicited NaKTI2 transcripts were only slightly reduced in JA-deficient plants, but were dramatically decreased in NaWRKY3- and NaWRKY6- silenced plants, respectively. Further electromobility shift assays indicated that NaWRKY3 and NaWRKY6 could directly bind to the promoter regions of NaKTI2 in vitro. Taken together, our results demonstrate that in addition to NaPI, NaKTI2, a pathogen- and herbivore-induced Kunitz trypsin inhibitor gene, is also required for herbivore resistance, and mainly regulated by NaWRKY3 and NaWRKY6.

Topics: Acetates; Alternaria; Animals; Cyclopentanes; Gene Expression Regulation, Plant; Gene Silencing; Herbivory; Larva; Nicotiana; Oxylipins; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Spodoptera; Transcription Factors; Trypsin Inhibitors

Protostane triterpenes in Alisma orientale (Sam.) Juz. have unique structural features with distinct pharmacological activities. Previously we have demonstrated that protostane triterpene biosynthesis could be regulated by methyl jasmonate (MeJA) induction in A. orientale. Here, proteomic investigation reveals the MeJA mediated regulation of protostane triterpene biosynthesis. In our study, 281 differentially abundant proteins were identified from MeJA-treated compared to control groups, while they were mainly associated with triterpene biosynthesis, α-linolenic acid metabolism, carbohydrate metabolism and response to stress/defense. Key enzymes 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), squalene epoxidase (SE), oxidosqualene cyclase (OSC) and cytochrome P450s which potentially involved in protostane triterpene biosynthesis were significantly enriched in MeJA-treated group. Basic Helix-loop-helix (bHLH), MYB, and GRAS transcription factors were enhanced after MeJA treatment, and they also improved the expressions of key enzymes in Mevalonate pathway and protostane triterpene. Then, MeJA also could increase the expression of α-galactosidase (α-GAL), thereby promoting carbohydrate decomposition, and providing energy and carbon skeletons for protostane triterpene precursor biosynthesis. As well, exogenous MeJA treatment upregulated 13-lipoxygenase (13-LOX), allene oxide synthase (AOS) and allene oxide cyclase (AOC) involved in α-linolenic acid metabolism, leading to the accumulation of endogenous MeJA and activation of the protostane triterpene biosynthesis transduction. Finally, MeJA upregulated stress/defence-related proteins, as to enhance the defence responses activity of plants. These results were further verified by quantitative real-time PCR analysis of 19 selected genes and content analysis of protostane triterpene. The results provide some new insights into the role of MeJA in protostane triterpene biosynthesis.

Topics: Acetates; Alisma; Amino Acid Sequence; Cyclopentanes; Gene Expression Regulation, Plant; Molecular Structure; Oxylipins; Protein Biosynthesis; Proteomics; Triterpenes

A transient heat stress occurring during early seed development in rice (Oryza sativa) reduces seed size by altering endosperm development. However, the relationship between the timing of the stress and specific developmental stage on heat sensitivity is not well-understood. To address this, we imposed a series of non-overlapping heat stress treatments and found that young seeds are most sensitive during the first two days after flowering. Temporal transcriptome analysis of developing, heat stressed (35°C) seeds during this window shows that Inositol-requiring enzyme 1 (IRE1)-mediated endoplasmic reticulum (ER) stress response and jasmonic acid (JA) pathways are the early (1-3 h) drivers of heat stress response. We propose that increased JA levels under heat stress may precede ER stress response as JA application promotes the spliced form of OsbZIP50, an ER response marker gene linked to IRE1-specific pathway. This study presents temporal and mechanistic insights into the role of JA and ER stress signalling during early heat stress response of rice seeds that impact both grain size and quality. Modulating the heat sensitivity of the early sensing pathways and downstream endosperm development genes can enhance rice resilience to transient heat stress events.

Topics: Acetates; Cell Cycle; Cyclopentanes; Endoplasmic Reticulum Stress; Endosperm; Gene Expression Regulation, Plant; Heat-Shock Response; Oryza; Oxylipins; Plant Growth Regulators; Plant Proteins; Seeds

Mildew severely reduces soybean yield and quality, and pods are the first line of defence against pathogens. Maize-soybean intercropping (MSI) reduces mildew incidence on soybean pods; however, the mechanism remains unclear. Changing light (CL) from maize shading is the most important environmental feature in MSI. We hypothesized that CL affects isoflavone accumulation in soybean pods, affecting their disease resistance. In the present study, shading treatments were applied to soybean plants during different developmental stages according to various CL environments under MSI. Chlorophyll fluorescence imaging (CFI) and classical evaluation methods confirmed that CL, especially vegetative stage shading (VS), enhanced pod resistance to mildew. Further metabolomic analyses and exogenous jasmonic acid (JA) and biosynthesis inhibitor experiments revealed the important relationship between JA and isoflavone biosynthesis, which had a synergistic effect on the enhanced resistance of CL-treated pods to mildew. VS promoted the biosynthesis and accumulation of constitutive isoflavones upstream of the isoflavone pathway, such as aglycones and glycosides, in soybean pods. When mildew infects pods, endogenous JA signalling stimulated the biosynthesis of downstream inducible malonyl isoflavone (MIF) and glyceollin to improve pod resistance.

Topics: Acetates; Chromatography, High Pressure Liquid; Cyclopentanes; Disease Resistance; Fusarium; Gene Expression Regulation, Plant; Glycine max; Isoflavones; Light; Lipoxygenase Inhibitors; Metabolomics; Oxylipins; Plant Diseases; Pyrazoles; Real-Time Polymerase Chain Reaction; Soybean Proteins; Tandem Mass Spectrometry

Two-line hybrid rice systems represent a new technical approach to utilizing the advantages of rice hybrids. However, the mechanism underlying the male sterile-line fertility transition in rice remains unclear. Peiai 64S (PA64S) is a photoperiod- and thermo-sensitive genic male sterile (PTGMS) line in which male sterility manifests at an average temperature above 23.5 °C under long-day (LD) conditions. Nongken 58S (NK58S) is a LD-sensitive genic male sterile (PGMS) rice that is sterile under LD conditions (above 13.75 h-day). In contrast, D52S is a short-day (SD)-PGMS line that manifests male sterility under SD conditions (below 13.5 h-day). In this study, we obtained fertile and sterile plants from all three lines and performed transcriptome analyses on the anthers of the plants. Gene ontology (GO) analysis suggested that the differentially expressed genes identified were significantly enriched in common terms involved in the response to jasmonic acid (JA) and in JA biosynthesis. On the basis of the biochemical and molecular validation of dynamic, tissue-specific changes in JA, indole-3-acetic acid (IAA) levels, gibberellin (GA) levels, and JA biosynthetic enzyme activities and expression, we proposed that JA could play a pivotal role in viable pollen production through its initial upregulation, constant fluctuation and leaf-spikelet signaling under certain fertility-inducing conditions. Furthermore, we also sprayed methyl jasmonate (MEJA) and salicylhydroxamic acid (SHAM) on the plants, thereby achieving fertility reversal in the PGMS lines NK58S and D52S, with 12.91-63.53% pollen fertility changes. Through qPCR and enzyme activity analyses, we identified two key enzymes-allene oxide synthase (AOS) and allene oxide cyclase (AOC)-that were produced and upregulated by 20-500-fold in PGMS in response to spraying; the activities of these enzymes reversed pollen fertility by influencing the JA biosynthetic pathway. These results provide a new understanding of hormone interactions and networks in male-sterile rice based on the role of JA that will help us to better understand the potential regulatory mechanisms of fertility development in rice in the future.

Topics: Acetates; Cyclopentanes; Fertility; Gene Expression Profiling; Gene Expression Regulation, Plant; Intramolecular Oxidoreductases; Oryza; Oxylipins; Plant Proteins; Pollen; Salicylamides; Signal Transduction

Dendrobium catenatum belongs to the Orchidaceae, and is a precious Chinese herbal medicine. In the past 20 years, D. catenatum industry has developed from an endangered medicinal plant to multi-billion dollar grade industry. The necrotrophic pathogen Sclerotium delphinii has a devastating effection on over 500 plant species, especially resulting in widespread infection and severe yield loss in the process of large-scale cultivation of D. catenatum. It has been widely reported that Jasmonate (JA) is involved in plant immunity to pathogens, but the mechanisms of JA-induced plant resistance to S. delphinii are unclear.. In the present study, the role of JA in enhancing D. catenatum resistance to S. delphinii was investigated. We identified 2 COI1, 13 JAZ, and 12 MYC proteins in D. catenatum genome. Subsequently, systematic analyses containing phylogenetic relationship, gene structure, protein domain, and motif architecture of core JA pathway proteins were conducted in D. catenatum and the newly characterized homologs from its closely related orchid species Phalaenopsis equestris and Apostasia shenzhenica, along with the well-investigated homologs from Arabidopsis thaliana and Oryza sativa. Public RNA-seq data were investigated to analyze the expression patterns of D. catenatum core JA pathway genes in various tissues and organs. Transcriptome analysis of MeJA and S. delphinii treatment showed exogenous MeJA changed most of the expression of the above genes, and several key members, including DcJAZ1/2/5 and DcMYC2b, are involved in enhancing defense ability to S. delphinii in D. catenatum.. The findings indicate exogenous MeJA treatment affects the expression level of DcJAZ1/2/5 and DcMYC2b, thereby enhancing D. catenatum resistance to S. delphinii. This research would be helpful for future functional identification of core JA pathway genes involved in breeding for disease resistance in D. catenatum.

Topics: Acetates; Basidiomycota; Cyclopentanes; Dendrobium; Disease Resistance; Gene Expression Regulation, Plant; Multigene Family; Oxylipins; Phylogeny; Plant Diseases; Plant Immunity; Plant Proteins; Signal Transduction

Symbiotic association of plants with arbuscular mycorrhizal (AM) fungi brings about changes in levels of the phytohormone jasmonate (JA) in root and shoot tissues of a plant. The enhanced JA levels not only play a role in controlling the extent of AM colonization but are also involved in the expression of mycorrhizal-induced resistance (MIR) against pathogens. We describe a method used to study the levels of a volatile jasmonate derivative, methyl jasmonate (MeJA), in tomato plants colonized by AM fungi and in response to subsequent attack by the foliar pathogen Alternaria alternata.

Topics: Acetates; Chromatography, Gas; Cyclopentanes; Disease Resistance; Fungi; Host-Pathogen Interactions; Mycorrhizae; Oxylipins; Plant Growth Regulators; Plant Roots; Symbiosis

Chlorophyll degradation is the main reason for postharvest yellowing of broccoli. To uncover the role of jasmonic acid (JA) on the degradation of chlorophyll, broccoli flowers were treated with exogenous methyl jasmonate (MeJA) and diethyldithiocarbamic acid (DIECA). We found a surge of endogenous JA content with the yellowing process, and a significant correlation between JA and chlorophyll content. MeJA treatments led to increased endogenous JA, increased allene oxide cyclase (AOC) activity, and enhanced expression of JA synthesis genes. MeJA caused a stronger reduction in the maximum quantum yield (Fv/Fm), fluorescence decline ratio (Rfd), and total chlorophyll content, advanced the peak of pheide a oxygenase (PAO) activity, and up-regulated the expression of chlorophyll degradation genes. The DIECA treatment resulted in lower endogenous levels of JA, and AOC and 12-oxo-phytodienoic acid reductase (OPR) activity. This study revealed that the potential role of JA on broccoli yellowing is to promote the chlorophyll degradation.

Topics: Acetates; Brassica; Chlorophyll; Cyclopentanes; Ditiocarb; Gene Expression Regulation, Plant; Intramolecular Oxidoreductases; Oxygenases; Oxylipins

Polyphenol oxidases (PPOs) as inducible defense proteins, contribute to tea (Camellia sinensis) resistance against tea geometrid larvae (Ectropis grisescens), and this resistance has been associated with the jasmonic acid (JA) signaling by testing geometrid performance in our previous work. However, the regulation of PPO-based defense by JA and other hormone signaling underlying these defense responses is poorly understood. Here, we investigated the role of phytohormones in regulating the PPO response to tea geometrids. We profiled levels of defense hormones, PPO activity and CsPPO genes in leaves infested with tea geometrids. Then, hormone levels were manipulated by exogenous application of methyl jasmonate (MeJA), gibberellin acid (GA

Topics: Abscisic Acid; Acetates; Animals; Antibiosis; Camellia sinensis; Catechol Oxidase; Cyclopentanes; Gibberellins; Herbivory; Larva; Moths; Oxylipins; Plant Growth Regulators; Plant Proteins; Signal Transduction

Cultivated sweet potato (

Topics: Acetates; Base Sequence; Cyclopentanes; Disease Resistance; DNA, Plant; Fusarium; Gene Expression Regulation, Plant; Genome, Plant; Ipomoea batatas; Models, Biological; Nicotiana; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Protein Binding; Transcription, Genetic

Decrease in the grain yield resulted from a low percentage of opened spikelets under high temperature (HT) during anthesis is a serious problem in the seed production of photo-thermo-sensitive genic male sterile (PTGMS) rice (Oryza sativa L.) lines, and the mechanism is little understood. Elucidating the physiological mechanism underlying the effect of HT during anthesis on spikelet-opening of PTGMS lines would have great significance in exploring the effective way to mitigate the adverse effect of HT. In this study, two PTGMS lines and one restorer line of rice were used and were subjected to normal temperature (NT) and HT treatments. The results showed that, compared with NT, HT significantly decreased the percentage of opened spikelets, fertilization percentage and seed-setting by significantly increasing the percentage of wrapped spikelets and reducing the spikelet-opening angle, length of spikelet-opening time. The HT significantly decreased the contents of soluble sugars, jasmonic acid (JA) and methyl jasmonate (MeJA) in the lodicules before and at glume-opening, which were significantly correlated with and accounts for the low percentage of opened spikelets under HT for rice, especially for the PTGMS lines.

Topics: Acetates; Cyclopentanes; Edible Grain; Fertility; Gene Expression Regulation, Plant; Heat-Shock Response; Hot Temperature; Inflorescence; Oryza; Oxylipins; Plant Growth Regulators; Plants, Genetically Modified; Seeds

Expression of VaNAC17 improved drought tolerance in transgenic Arabidopsis by upregulating stress-responsive genes, modulating JA biosynthesis, and enhancing ROS scavenging. Water deficit severely affects the growth and development of plants such as grapevine (Vitis spp.). Members of the NAC (NAM, ATAF1/2, and CUC2) transcription factor (TF) family participate in drought-stress-induced signal transduction in plants, but little is known about the roles of NAC genes in drought tolerance in grapevine. Here, we explored the role of VaNAC17 in Vitis amurensis, a cold-hardy, drought-tolerant species of grapevine. VaNAC17 was strongly induced in grapevine by drought, exogenous abscisic acid (ABA), and methyl jasmonate (MeJA). A transient expression assay in yeast indicated that VaNAC17 functions as a transcriptional activator. Notably, heterologous expression of VaNAC17 in Arabidopsis thaliana enhanced drought tolerance. VaNAC17-expressing Arabidopsis plants showed decreased reactive oxygen species (ROS) accumulation compared to wild-type plants under drought conditions. RNA-seq analysis indicated that VaNAC17 expression increased the transcription of downstream stress-responsive genes after 5 days of drought treatment, especially genes involved in jasmonic acid (JA) biosynthesis (such as LOX3, AOC1 and OPR3) and signaling (such as MYC2, JAZ1, VSP1 and CORI3) pathways. Endogenous JA levels increased in VaNAC17-OE plants under drought stress. Taken together, these results indicate that VaNAC17 plays a positive role in drought tolerance by modulating endogenous JA biosynthesis and ROS scavenging.

Topics: Abscisic Acid; Acetates; Arabidopsis; Cyclopentanes; Droughts; Endopeptidases; Gene Expression Regulation, Plant; Oxidoreductases; Oxylipins; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Reactive Oxygen Species; RNA-Seq; Stress, Physiological; Transcription Factors; Vitis

Jasmonates (JAs) are key phytohormones involved in regulation of plant growth and development, stress responses, and secondary metabolism. It has been reported that treatments with JAs could increase the contents of Amaryllidaceae alkaloids in Amaryllidaceae plants. Jasmonate ZIM (zinc-finger inflorescence meristem) domain (JAZ) proteins are key components in JA signal processes. However, JAZ proteins have not been characterized in genus Lycoris. In this study, we identified and cloned seven differentially expressed JAZ genes (namely LaJAZ1-LaJAZ7) from Lycoris aurea. Bioinformatic analyses revealed that these seven LaJAZ proteins contain the ZIM domain and JA-associated (Jas, also named CCT_2) motif. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis revealed that these LaJAZ genes display different expression patterns in L. aurea tissues, and most of them are inducible when treated with methyl jasmonate (MeJA) treatment. Subcellular localization assay demonstrated that LaJAZ proteins are localized in the cell nucleus or cytoplasm. In addition, LaJAZ proteins could interact with each other to form homodimer and/or heterodimer. The findings in this study may facilitate further functional research of the LaJAZ genes, especially the potential regulatory mechanism of plant secondary metabolites including Amaryllidaceae alkaloids in L. aurea.

Topics: Acetates; Cell Nucleus; Computational Biology; Cyclopentanes; Cytoplasm; Gene Expression Regulation, Plant; Lycoris; Oxylipins; Plant Growth Regulators; Plant Proteins; Protein Domains; Zinc Fingers

JAZ (Jasmonate ZIM-domain) proteins play pervasive roles in plant development and defense reaction. However, limited information is known about the JAZ family in

Topics: Acetates; Camellia sinensis; Cyclopentanes; Escherichia coli; Gene Expression Regulation, Plant; Genome, Plant; Hormones; Multigene Family; Oxylipins; Phylogeny; Plant Proteins; Promoter Regions, Genetic; Repressor Proteins; Stress, Physiological

In response to various stimuli, plants acquire resistance against pests and/or pathogens. Such acquired or induced resistance allows plants to rapidly adapt to their environment. Spraying the bark of mature Norway spruce (Picea abies) trees with the phytohormone methyl jasmonate (MeJA) enhances resistance to tree-killing bark beetles and their associated phytopathogenic fungi. Analysis of spruce chemical defenses and beetle colonization success suggests that MeJA treatment both directly induces immune responses and primes inducible defenses for a faster and stronger response to subsequent beetle attack. We used metabolite and transcriptome profiling to explore the mechanisms underlying MeJA-induced resistance in Norway spruce. We demonstrated that MeJA treatment caused substantial changes in the bark transcriptional response to a triggering stress (mechanical wounding). Profiling of mRNA expression showed a suite of spruce inducible defenses are primed following MeJA treatment. Although monoterpenes and diterpene resin acids increased more rapidly after wounding in MeJA-treated than control bark, expression of their biosynthesis genes did not. We suggest that priming of inducible defenses is part of a complex mixture of defense responses that underpins the increased resistance against bark beetle colonization observed in Norway spruce. This study provides the most detailed insights yet into the mechanisms underlying induced resistance in a long-lived gymnosperm.

Topics: Acetates; Animals; Coleoptera; Cyclopentanes; DNA Methylation; Gene Expression Regulation, Plant; Histones; Monoterpenes; Oxylipins; Phenotype; Picea; Plant Bark; Plant Growth Regulators; Plant Proteins

Methyl jasmonate (MeJA) and its free-acid form, jasmonic acid (JA), collectively referred to as jasmonates (JAs), are natural plant growth regulators that are widely present in higher plants. Simultaneous detection of JA and MeJA in plant samples is of significance and is a great challenging issue. In this study, coupling with two extraction methods, a sensitive monoclonal antibody (mAb) based enzyme-linked immunosorbent assay (ELISA) for simultaneous detection of JA and MeJA in plant samples was developed. The JA-bovine serum albumin (BSA) conjugate was used as an immunogen for the production of mAb. As the produced mAb exhibited higher recognition ability towards MeJA than towards JA, ELISA was established using MeJA as the standard. Under optimal experimental conditions, the IC

Topics: Acetates; Animals; Antibodies, Monoclonal; Cyclopentanes; Enzyme-Linked Immunosorbent Assay; Female; Flowers; Fruit; Mice, Inbred BALB C; Oxylipins; Plant Growth Regulators; Plant Leaves; Salvia; Solid Phase Extraction; Vitis

Methyl jasmonate improved yield of both rice varieties under arsenic toxicity by alleviating oxidative stress through increasing the activity of antioxidant enzymes and decreasing arsenic accumulation by modulating arsenic transporters. Human health and rice cultivation are threatened by arsenic (As) contamination. Methyl jasmonate (MJ), as a regulator of plant growth, plays an important role in response to environmental stresses. In the present study, the effects of MJ (0, 0.5 and 1 µM) on yield, biochemical and molecular traits of two rice varieties (T. hashemi and Fajr) under As treatments (0, 25 and 50 µM) were investigated. The results showed that As decreased chlorophyll content, chlorophyll fluorescence and biomass production; however, MJ improved photosynthetic pigments and plant growth. As also induced oxidative stress (H

Topics: Acetates; Antioxidants; Arsenic; Cyclopentanes; Fluorescence; Glutathione; Hydrogen Peroxide; Iron; Lipid Peroxidation; Malondialdehyde; Membrane Transport Proteins; Oryza; Oxylipins; Photosynthesis; Pigments, Biological; Plant Leaves; Plant Roots

The effects of jasmonic acid (JA) and methyl jasmonate (Me-JA) on photosynthetic efficiency and expression of some photosystem (PSII) related in different cultivars of Brassica oleracea L. (var. italica, capitata, and botrytis) were investigated. Plants raised from seeds subjected to a pre-sowing soaking treatment of varying concentrations of JA and Me-JA showed enhanced photosynthetic efficiency in terms of qP and chlorophyll fluorescence. Maximum quantum efficiency of PSII (Fv/Fm) was increased over that in the control seedlings. This enhancement was more pronounced in the Me-JA-treated seedlings compared to that in JA-treated ones. The expression of PSII genes was differentially regulated among the three varieties of B. oleracea. The gene PsbI up-upregulated in var. botrytis after treatment of JA and Me-JA, whereas PsbL up-regulated in capitata and botrytis after supplementation of JA. The gene PsbM showed many fold enhancements in these expressions in italica and botrytis after treatment with JA. However, the expression of the gene PsbM increased by both JA and Me-JA treatments. PsbTc(p) and PsbTc(n) were also found to be differentially expressed which revealed specificity with the variety chosen as well as JA or Me-JA treatments. The RuBP carboxylase activity remained unaffected by either JA or Me-JA supplementation in all three varieties of B. oleracea L. The data suggest that exogenous application of JA and Me-JA to seeds before germination could influence the assembly, stability, and repair of PS II in the three varieties of B. oleracea examined. Furthermore, this improvement in the PS II machinery enhanced the photosynthetic efficiency of the system and improved the photosynthetic productivity in terms of saccharides accumulation.

Topics: Acetates; Brassica; Carbohydrate Metabolism; Carotenoids; Chlorophyll; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Photosynthesis; Photosystem II Protein Complex; Plant Shoots; Ribulose-Bisphosphate Carboxylase; Seedlings; Seeds; Sugars

Crosstalk between salicylic acid (SA) and jasmonic acid (JA) signaling plays an important role in regulation of plant senescence. Our previous work found that SA could delay methyl jasmonate (MeJA)-induced leaf senescence in a concentration-dependent manner. Here, the effect of low concentration of SA (LCSA) application on MeJA-induced leaf senescence was further assessed. High-throughput sequencing (RNA-Seq) results showed that LCSA did not have dominant effects on the genetic regulatory pathways of basal metabolism like nitrogen metabolism, photosynthesis and glycolysis. The ClusterONE was applied to identify discrete gene modules based on protein-protein interaction (PPI) network. Interestingly, an autophagy-related (ATG) module was identified in the differentially expressed genes (DEGs) that exclusively induced by MeJA together with LCSA. RT-qPCR confirmed that the expression of most of the determined ATG genes were upregulated by LCSA. Remarkably, in contrast to wild type (Col-0), LCSA cannot alleviate the leaf yellowing phenotype in autophagy defective mutants (atg5-1 and atg7-2) upon MeJA treatment. Confocal results showed that LCSA increased the number of autophagic bodies accumulated in the vacuole during MeJA-induced leaf senescence. Collectively, our work revealed up-regulation of autophagy by LCSA as a key regulator to alleviate MeJA-induced leaf senescence.

Topics: Acetates; Aging; Autophagy; Autophagy-Related Protein 5; Autophagy-Related Protein 7; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Plant Leaves; RNA-Seq; Salicylic Acid; Signal Transduction

Methyl jasmonate (MeJA) is an airborne signaling phytohormone that can induce changes in endogenous jasmonates (JAs) and cause photosynthetic responses. However, the response of these two aspects of citrus plants at different MeJA concentrations is still unclear. Four MeJA concentrations were used in two citrus varieties, Huangguogan (C. reticulata × C. sinensis) and Shiranuhi [C. reticulata × (C. reticulata × C. sinensis)], to investigate the effects of MeJA dose on the endogenous JAs pathway and photosynthetic capacity. We observed that MeJA acted in a dose-dependent manner, and its stimulation in citrus leaves showed a bidirectional character at different concentrations. This work demonstrates that MeJA at only a concentration of 2.2 mM or less contributed to the activation of magnesium protoporphyrin IX methyltransferase (ChlM, EC 2.1.1.11) and protochlorophyllide oxidoreductase (POR, EC 1.3.1.11) and the simultaneous accumulation of Chl a and Chl b, which in turn contributed to an improved photosynthetic capacity and PSII photochemistry efficiency of citrus. Meanwhile, the inhibition of endogenous JAs synthesis by exogenous MeJA was observed. This was achieved by reducing the ratio of monogalactosyl diacylglycerol (MGDG) to diagalactosyl diacylglycerol (DGDG) and inhibiting the activities of key enzymes in JAs synthesis, especially 12-oxo-phytodienoic acid reductase (OPR, EC 1.3.1.42). Another noteworthy finding is that there may exist a JA-independent pathway that could regulate 12-oxo-phytodienoic acid (OPDA) synthesis. This study jointly analyzed the internal hormone regulation mechanism and the external physiological response, as well as revealed the effects of exogenous MeJA on promoting the photosynthesis and inhibiting the endogenous JAs synthesis.

Topics: Acetates; Citrus; Cyclopentanes; Oxylipins; Photosynthesis

Fusarium oxysporum f. sp. niveum (FON) causes Fusarium wilt in watermelon. Several disease-resistant watermelon varieties have been developed to combat Fusarium wilt. However, the key metabolites that mount defense responses in these watermelon varieties are unknown. Herein, we analyzed hormones, melatonin, phenolic acids, and amino acid profiles in the leaf tissue of FON zero (0)-resistant (PI-296341, Calhoun Grey, and Charleston Grey) and -susceptible (Sugar Baby) watermelon varieties before and after infection.. We found that jasmonic acid-isoleucine (JA-Ile) and methyl jasmonate (MeJA) were selectively accumulated in one or more studied resistant varieties upon infection. However, indole-3-acetic acid (IAA) was only observed in the FON 0 inoculated plants of all varieties on the 16th day of post-inoculation. The melatonin content of PI-296341 decreased upon infection. Conversely, melatonin was only detected in the FON 0 inoculated plants of Sugar Baby and Charleston Grey varieties. On the 16th day of post-inoculation, the lysine content in resistant varieties was significantly reduced, whereas it was found to be elevated in the susceptible variety.. Taken together, Me-JA, JA-Ile, melatonin, and lysine may have crucial roles in developing defense responses against the FON 0 pathogen, and IAA can be a biomarker of FON 0 infection in watermelon plants.

Topics: Acetates; Amino Acids; Citrullus; Cyclopentanes; Disease Resistance; Fusarium; Host-Pathogen Interactions; Hydroxybenzoates; Lysine; Melatonin; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Leaves

The LATERAL ORGAN BOUNDARIES DOMAIN (LBD)-containing genes are plant-specific genes that play important roles in lateral organ development. In this study, we identified LBD40 (Solyc02g085910), which belongs to subfamily II of the LBD family of genes in tomato. LBD40 was highly expressed in roots and fruit. LBD40 expression was significantly induced by PEG and salt. Moreover, SlLBD40 expression was induced by methyl jasmonate treatment, while SlLBD40 expression could not be induced in the jasmonic acid-insensitive1 (jai1) mutant or MYC2-silenced plants, in which jasmonic acid (JA) signaling was disrupted. These findings demonstrate that SlLBD40 expression was dependent on JA signaling and that it might be downstream of SlMYC2, which is the master transcription factor in the JA signal transduction pathway. Overexpressing and CRISPR/Cas9 mediated knockout transgenic tomato plants were generated to explore SlLBD40 function. The drought tolerance test showed that two SlLBD40 knockout lines wilted slightly, while SlLBD40 overexpressing plants suffered severe wilting. The statistical water loss rate and midday leaf water potential also confirmed that knockout of SlLBD40 improved the water-holding ability of tomato under drought conditions. Taken together, our study demonstrates that SlLBD40, involved in JA signaling, was a negative regulator of drought tolerance and that knockout of SlLBD40 enhanced drought tolerance in tomato. This study also provides a novel function of SlLBD40, which belongs to subfamily II of LBD genes.

Topics: Acetates; CRISPR-Cas Systems; Cyclopentanes; Droughts; Fruit; Mutagenesis; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plant Roots; Plants, Genetically Modified; Solanum lycopersicum; Transcription Factors

Jasmonic acid (JA) is thought to be involved in plant responses to cadmium (Cd) stress, but the underlying molecular mechanisms are poorly understood. Here, we show that Cd treatment rapidly induces the expression of genes promoting endogenous JA synthesis, and subsequently increases the JA concentration in Arabidopsis roots. Furthermore, exogenous methyl jasmonate (MeJA) alleviates Cd-generated chlorosis of new leaves by decreasing the Cd concentration in root cell sap and shoot, and decreasing the expression of the AtIRT1, AtHMA2 and AtHMA4 genes promoting Cd uptake and long-distance translocation, respectively. In contrast, mutation of a key JA synthesis gene, AtAOS, greatly enhances the expression of AtIRT1, AtHMA2 and AtHMA4, increases Cd concentration in both roots and shoots, and confers increased sensitivity to Cd. Exogenous MeJA recovers the enhanced Cd-sensitivity of the ataos mutant, but not of atcoi1, a JA receptor mutant. In addition, exogenous MeJA reduces NO levels in Cd-stressed Arabidopsis root tips. Taken together, our results suggest that Cd-induced JA acts via the JA signaling pathway and its effects on NO levels to positively restrict Cd accumulation and alleviates Cd toxicity in Arabidopsis via suppression of the expression of genes promoting Cd uptake and long-distance translocation.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cadmium; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins

Chilling injury (CI) is a physiological disorder induced by cold, which heavily limit crop production and postharvest preservation worldwide. Methyl jasmonate (MeJA) can alleviate CI in various fruit species, including peach; however, the underlying molecular mechanism is poorly understood. Here, changes in contents of phenolics, lipids, and jasmonic acid (JA) and gene expressions are compared between MeJA and control fruit. Exogenous MeJA inhibited expressions of

Topics: Acetates; Cold Temperature; Cyclopentanes; Fruit; Gene Expression Regulation, Plant; Oxylipins; Phospholipids; Plant Growth Regulators; Plant Proteins; Prunus persica

The JASMONATE ZIM DOMAIN (JAZ) proteins act as negative regulators in the jasmonic acid (JA) signaling pathways of plants, and these proteins have been reported to play key roles in plant secondary metabolism mediated by JA. In this study, we firstly isolated one JAZ from

Topics: Acetates; Amino Acid Sequence; Cell Nucleus; Cyclopentanes; Gene Expression Regulation, Plant; Gene Silencing; Isomerases; Oxylipins; Phylogeny; Plant Growth Regulators; Plant Leaves; Plant Proteins; Pogostemon; Protoplasts; Repressor Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Sesquiterpenes; Signal Transduction; Trans-Activators; Two-Hybrid System Techniques

Members of the Brassicales contain an organelle, the endoplasmic reticulum (ER) body, which is derived from the ER. Recent studies have shed light on the biogenesis of the ER body and its physiological role in plants. However, formation of the ER body and its physiological role are not fully understood. Here, we investigated the physiological role of TSK-associating protein 1 (TSA1), a close homolog of NAI2 that is involved in ER body formation, and provide evidence that it is involved in ER body biogenesis under wound-related stress conditions. TSA1 is N-glycosylated and localizes to the ER body as a luminal protein. TSA1 was highly induced by the plant hormone, methyl jasmonate (MeJA). Ectopic expression of TSA1:GFP induced ER body formation in root tissues of transgenic Arabidopsis thaliana and in leaf tissues of Nicotiana benthamiana. TSA1 and NAI2 formed a heterocomplex and showed an additive effect on ER body formation in N. benthamiana. MeJA treatment induced ER body formation in leaf tissues of nai2 and tsa1 plants, but not nai2/tsa1 double-mutant plants. However, constitutive ER body formation was altered in young seedlings of nai2 plants but not tsa1 plants. Based on these results, we propose that TSA1 plays a critical role in MeJA-induced ER body formation in plants.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Calcium-Binding Proteins; Cyclopentanes; Endoplasmic Reticulum; Gene Expression; Green Fluorescent Proteins; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Leaves; Plants, Genetically Modified; Seedlings

Petal color, size, and morphology play important roles in protecting other floral organs, attracting pollinators, and facilitating sexual reproduction in plants. In a previous study, we obtained a petal degeneration mutant (

Topics: Acetates; Brassica; Cyclopentanes; Flowers; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Mutation; Oxylipins; Phenotype; Plant Proteins

Plant growth promoting bacteria (PGPB) are agriculturally important soil bacteria that increase plant growth. We subjected peppermint to inoculation with three species of PGPB. After inoculation, the plants were sprayed with methyl jasmonate solution (MeJA) or SA (salicylic acid). Then, the plants were harvested and the plant growth parameters, trichome density, EO content and endogenous phytohormones were measured. Shoot fresh weight was reduced in plants inoculated and treated with MeJA whereas EO content varied depending on the MeJA concentration applied. Plants inoculated and treated with MeJA 2 mM showed the maximum increase in EO production, revealing a synergism between PGPB and MeJA. SA treatments also enhanced EO yield. The increased growth and EO production observed upon PGPB application were at least partly due to an increase in the JA and SA concentrations in the plant, as well as to an associated rise in the glandular trichome density.

Topics: Acetates; Bacillus subtilis; Cyclopentanes; Gene Expression Regulation, Plant; Mentha piperita; Oils, Volatile; Oxylipins; Plant Development; Plant Growth Regulators; Plant Leaves; Plant Shoots; Pseudomonas fluorescens; Pseudomonas putida; Salicylic Acid; Trichomes

Members of the Jasmonate ZIM domain (JAZ) proteins act as transcriptional repressors in the jasmonate (JA) hormonal response. To characterize the potential roles of JAZ gene family in plant development and abiotic stress response, fifteen JAZs were identified based on the genome of Nicotiana tabacum. Structural analysis confirmed the presence of single Jas and TIFY motif. Tissue expression pattern analysis indicated that NtJAZ-2, -3, -5, and -10 were highly expressed in roots and NtJAZ-11 was expressed only in the cotyledons. The transcript level of NtJAZ-3, -5, -9, and -10 in the stem epidermis was higher than that in the stem without epidermis. Dynamic expression of NtJAZs exposed to abiotic stress and phytohormone indicated that the expression of most NtJAZs was activated by salicylic acid, methyl jasmonate, gibberellic acid, cold, salt, and heat stresses. With abscisic acid treatment, NtJAZ-1, -2, and -3 were not activated; NtJAZ-4, -5, and -6 were up-regulated; and the remaining NtJAZ genes were inhibited. With drought stress, the expression of NtJAZ-1, -2, -3, -4, -5, -6, -7, and -8 was up-regulated, whereas the transcript of the remaining genes was inhibited. Moreover, high concentration MeJA (more than 1 mM MeJA) had an effect on secreting trichome induction, but inhabited the plant growth. Nine NtJAZs may play important role in secreting trichome induction. These results indicate that the JAZ proteins are convergence points for various phytohormone signal networks, which are involved in abiotic stress responses.

Topics: Acetates; Amino Acid Motifs; Arabidopsis; Chromosomes; Cyclopentanes; Databases, Genetic; Gene Expression Profiling; Gene Expression Regulation, Plant; Markov Chains; Nicotiana; Oxylipins; Phylogeny; Plant Growth Regulators; Plant Proteins; Plant Roots; Repressor Proteins; Signal Transduction; Stress, Physiological; Transcription Factors; Trichomes

An enzyme is crucial for the formation of Hedychium coronarium scent and defense responses, which may be responsible for the biosynthesis of allo-ocimene in H. coronarium. Hedychium coronarium can emit a strong scent as its main scent constituents are monoterpenes and their derivatives. Among these derivatives, allo-ocimene is not only a very important volatile substance in flower aroma, but is also crucial to plant defense. However, the molecular mechanism of allo-ocimene biosynthesis has not been characterized in plants. In this study, a new alcohol dehydrogenase gene, HcADH, was cloned. The amino acid sequences encoded by HcADH contained the most conserved motifs of short chain alcohol dehydrogenase/reductases (SDRs), which included NAD

Topics: Acetates; Acyclic Monoterpenes; Cyclopentanes; Flowers; Gene Expression Profiling; Gene Expression Regulation, Plant; Oxylipins; Plant Proteins; Polyenes; Short Chain Dehydrogenase-Reductases; Signal Transduction; Terpenes; Zingiberaceae

As waterlogging and successive events severely influence growth and development of economically important plants, we attempted to characterize the role of a waterlogging-responsive group I (A-6) ethylene response factor (MaRAP2-4) from Mentha arvensis. Waterlogging, ethylene and methyl jasmonate rapidly induced the expression of MaRAP2-4. MaRAP2-4 interacted with multiple cis-elements like dehydration response elements (DRE1/2), anoxia/jasmonic acid response element (JARE) and GCC box showing its involvement in multiple responses. MaRAP2-4 localizes in the nucleus and acts as a transcriptional activator. Truncation and internal deletion identified a 20 amino acids potential transactivation domain (PLPSSVDAKLEAICQSLAIN) in MaRAP2-4. MaRAP2-4 transgenic Arabidopsis showed enhanced waterlogging and subsequent oxidative stress tolerance. Microarray analysis revealed that within up-regulated genes 483, 212 and 132 promoters carry either single or multiple copies of DRE, JARE and GCC cis-element/s, respectively. Within these promoters, a large section belongs to carbohydrate metabolism/transport, including many SWEET transporters. Further analysis showed MaRAP2-4 specifically targets two positions in AtSWEEET10 promoter carrying DRE and/or GCC box that might regulate carbohydrate availability and waterlogging tolerance. These results demonstrate that MaRAP2-4 is a positive regulator of waterlogging tolerance, and as energy-consuming processes such as carbohydrate biosynthesis are reduced under waterlogging-induced hypoxia, sugar transport through SWEETs may be the primary option to make sugar available to the required tissue.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Gene Expression Regulation, Plant; Mentha; Oxylipins; Plants, Genetically Modified; Promoter Regions, Genetic

Plants have evolved effective mechanisms to protect themselves against multiple stresses, and employ jasmonates (JAs) as vital defence signals to defend against pathogen infection. The accumulation of JA, induced by signals from biotic and abiotic stresses, results in the degradation of Jasmonate-ZIM-domain (JAZ) proteins, followed by the de-repression of JAZ-repressed transcription factors (such as MYC2) to activate defence responses and developmental processes. Here, we characterized a JAZ family protein, GhJAZ2, from cotton (Gossypium hirsutum) which was induced by methyl jasmonate (MeJA) and inoculation of Verticillium dahliae. The overexpression of GhJAZ2 in cotton impairs the sensitivity to JA, decreases the expression level of JA-response genes (GhPDF1.2 and GhVSP) and enhances the susceptibility to V. dahliae and insect herbivory. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that GhJAZ2 may be involved in the regulation of cotton disease resistance by interaction with further disease-response proteins, such as pathogenesis-related protein GhPR10, dirigent-like protein GhD2, nucleotide-binding site leucine-rich repeat (NBS-LRR) disease-resistant protein GhR1 and a basic helix-loop-helix transcription factor GhbHLH171. Unlike MYC2, overexpression of GhbHLH171 in cotton activates the JA synthesis and signalling pathway, and improves plant tolerance to the fungus V. dahliae. Molecular and genetic evidence shows that GhJAZ2 can interact with GhbHLH171 and inhibit its transcriptional activity and, as a result, can restrain the JA-mediated defence response. This study provides new insights into the molecular mechanisms of GhJAZ2 in the regulation of the cotton defence response.

Topics: Acetates; Cyclopentanes; Gene Expression Regulation, Plant; Gossypium; Oxylipins; Plant Diseases; Plant Proteins; Verticillium

Bacillus amyloliquefaciens FZB42 is a type of plant growth-promoting rhizobacterium (PGPR) which activates induced systemic resistance (ISR) in Arabidopsis. Blocking of the synthesis of cyclic lipopeptides and 2,3-butanediol by FZB42, which have been demonstrated to be involved in the priming of ISR, results in the abolishment of the plant defence responses. To further clarify the ISR activated by PGPRs at the microRNA (miRNA) level, small RNA (sRNA) libraries from Arabidopsis leaves after root irrigation with FZB42, FZB42ΔsfpΔalsS and control were constructed and sequenced. After fold change selection, promoter analysis and target prediction, miR846-5p and miR846-3p from the same precursor were selected as candidate ISR-associated miRNAs. miR846 belongs to the non-conserved miRNAs, specifically exists in Arabidopsis and its function in the plant defence response remains unclear. The disease severity of transgenic Arabidopsis overexpressing miR846 (OEmiR846) or knockdown miR846 (STTM846) against Pseudomonas syringae DC3000 suggests that the miR846 expression level in Arabidopsis is negatively correlated with disease resistance. Moreover, miR846 in Arabidopsis Col-0 is repressed after methyl jasmonate treatment. In addition, jasmonic acid (JA) signalling-related genes are up-regulated in STTM846, and the stomatal apertures of STTM846 are also less than those in Arabidopsis Col-0 after methyl jasmonate treatment. Furthermore, the disease resistance of STTM846 transgenic Arabidopsis against Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) is blocked by the addition of the JA biosynthetic inhibitor diethyldiethiocarbamic acid (DIECA). Taken together, our results suggest that B. amyloliquefaciens FZB42 inoculation suppresses miR846 expression to induce Arabidopsis systemic resistance via a JA-dependent signalling pathway.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Bacillus amyloliquefaciens; Cyclopentanes; Gene Expression Regulation, Plant; MicroRNAs; Oxylipins; Plant Diseases; Signal Transduction

Stomatal immunity restricts bacterial entry to leaves through the recognition of microbe-associated molecular patterns (MAMPs) by pattern-recognition receptors (PRRs) and downstream abscisic acid and salicylic acid signaling. Through a reverse genetics approach, we characterized the function of the L-type lectin receptor kinase-V.2 (LecRK-V.2) and -VII.1 (LecRK-VII.1). Analyses of interactions with the PRR FLAGELLIN SENSING2 (FLS2) were performed by co-immunoprecipitation and bimolecular fluorescence complementation and whole-cell patch-clamp analyses were used to evaluate guard cell Ca

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Cell Membrane; Cyclopentanes; Disease Resistance; Flagellin; Ion Channel Gating; Mutation; Oxylipins; Plant Diseases; Plant Immunity; Plant Stomata; Protein Binding; Protein Kinases; Protein Serine-Threonine Kinases; Reactive Oxygen Species

Apple coloration is very important for most cultivars. The application of jasmonate can effectively enhance the coloration of apple fruit, but it might ruin the fruit's storage potential. Here, we report that applying methyl jasmonate on apple fruit 3 weeks before commercial harvest not only enhanced the fruit coloration but also did not affect its storage potential. Our findings provide important information for enhancing apple coloration using jasmonate.

Topics: Acetates; Anthocyanins; Cyclopentanes; Ethylenes; Fruit; Malus; Oxylipins; Pigmentation; Preservation, Biological

Myelocytomatosis (MYC) transcription factors (TFs) are key regulators of the jasmonic acid (JA) signaling pathway. In cell cultures, methyl jasmonate (MeJA) can improve the production of taxol, which is a complex terpenoid compound with an intense antitumor activity. However, the functions of MYC genes in Taxus sp. (yew trees) remain poorly known. Based on Taxus sp. transcriptome changes induced by MeJA, a TcMYC gene was isolated in a previous study. Here, we further characterized the TcMYC TF encoded by that gene and four other yew MYC TFs previously obtained. Three yew MYC TFs had the typical basic helix-loop-helix (bHLH)-MYC_N region, but the other two MYC did not, although all five presented the bHLH domain. TcMYC was localized to the nuclei, and phylogenetic analysis indicated that the yew MYC TFs were closely related to Arabidopsis thaliana MYC1/2 and maize R protein. The yeast one-hybrid assay showed that TcMYC binds the G-box of the promoter of taxane 5α-hydroxylase. Transcript levels of TcMYC revealed that TcMYC was highly expressed in xylem and leaves, and up-regulated by drought and high-salinity stresses. Coronatine (COR) has recently been used as a new elicitor to improve the production of taxol in cell cultures; TcMYC was strongly expressed at 2 and 4 h after COR treatment, but decreased at 12 and 24 h. Overall, the results obtained here provide new insights into the potential regulatory roles of MYC TFs on taxol biosynthesis in yew trees.

Topics: Acetates; Cloning, Molecular; Cyclopentanes; Gene Expression Regulation, Plant; Genes, myc; Genes, Plant; Metabolic Networks and Pathways; Oxylipins; Phylogeny; Taxus; Transcription Factors; Transcriptome

Topics: Acetates; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Mentha; Monoterpenes; Oxylipins; Plant Proteins; Signal Transduction; Transcription Factors

Target of rapamycin (TOR) acts as an important regulator of cell growth, development and stress responses in most examined diploid eukaryotes. However, little is known about TOR in tetraploid species such as cotton. Here, we show that TORC1-S6K-RPS6, the major signaling components, are conserved and further expanded in cotton genome. Though the cotton seedlings are insensitive to rapamycin, AZD8055, the second-generation inhibitor of TOR, can significantly suppress the growth in cotton. Global transcriptome analysis revealed that genes associated with jasmonic acid (JA) biosynthesis and transduction were significantly altered in AZD8055 treated cotton seedlings, suggesting the potential crosstalk between TOR and JA signaling. Pharmacological and genetic approaches have been employed to get further insights into the molecular mechanism of the crosstalk between TOR and JA. Combination of AZD8055 with methyl jasmonate can synergistically inhibit cotton growth, and additionally JA levels were significantly increased when cotton seedlings were subjected to AZD8055. JA biosynthetic and signaling mutants including jar1, coi1-2 and myc2-2 displayed TOR inhibitor-resistant phenotypes, whereas COI1 overexpression transgenic lines and jaz10 exhibited sensitivity to AZD8055. Consistently, cotton JAZ can partially rescue TOR-suppressed phenotypes in Arabidopsis. These evidences revealed that the crosstalk between TOR and JA pathway operates in cotton and Arabidopsis.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Gossypium; Morpholines; Oxylipins; Phosphatidylinositol 3-Kinases; Plants, Genetically Modified; Seedlings; Signal Transduction; Sirolimus

Jasmonates (JAs) are well-known regulators of stress, defence, and secondary metabolism in plants, with JA perception triggering extensive transcriptional reprogramming, including both activation and/or repression of entire metabolic pathways. We performed RNA sequencing based transcriptomic profiling of tobacco BY-2 cells before and after treatment with methyl jasmonate (MeJA) to identify novel transcriptional regulators associated with alkaloid formation. A total of 107,140 unigenes were obtained through de novo assembly, and at least 33,213 transcripts (31%) encode proteins, in which 3419 transcription factors (TFs) were identified, representing 72 gene families, as well as 840 transcriptional regulators (TRs) distributed among 19 gene families. After MeJA treatment BY-2 cells, 7260 differentially expressed transcripts were characterised, which include 4443 MeJA-upregulated and 2817 MeJA-downregulated genes. Of these, 227 TFs/TRs in 36 families were specifically upregulated, and 102 TFs/TRs in 38 families were downregulated in MeJA-treated BY-2 cells. We further showed that the expression of 12 ethylene response factors and four basic helix-loop-helix factors increased at the transcriptional level after MeJA treatment in BY-2 cells and displayed specific expression patterns in nic mutants with or without MeJA treatments. Our data provide a catalogue of transcripts of tobacco BY-2 cells and benefit future study of JA-modulated regulation of secondary metabolism in tobacco.

Topics: Acetates; Alkaloids; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Nicotiana; Oxylipins; Plant Proteins; Transcription Factors

Numerous studies have demonstrated the function of salinity or jasmonic acid (JA) in plant growth and senescence. This study evaluated how the combination of salinity and methyl jasmonate (MeJA) (SaM) worked as a novel stress and then regulated plant growth in Arabidopsis. Firstly, we found that compared with MeJA or NaCl treatment alone, SaM would significantly intensified plant growth inhibition and senescence in wild-type (WT) seedlings, and these phenotypes could be partially compromised after SaM stress in JA-insensitive mutants. Meanwhile, genes involved in JA signaling and Senescence Associated Gene 13 (SAG13) were dramatically increased by SaM stress than that by MeJA or NaCl alone in WT. Moreover, a group of secondary metabolite - indolic glucosinolates (IGs) showed obvious over-accumulation after SaM treatment than that after each single one in WT, and the seedlings treated with IGs' metabolites performed similar inhibited growth and chlorotic leaves phenotypes compared with those caused by SaM stress. All these indicated the toxicity of IGs and their metabolites would prevent the growth progress of plants. Therefore, we concluded that SaM worked as a novel stress and intensified plant growth inhibition and senescence, which was dependent on JA-dependent and -independent signaling pathways.

Topics: Acetates; Aging; Arabidopsis; Cyclopentanes; Oxylipins; Plant Growth Regulators; Plant Leaves; Seedlings; Signal Transduction; Sodium Chloride

Plants respond to herbivory by reconfiguring hormonal networks, increasing secondary metabolite production and decreasing growth. Furthermore, some plants display a decrease in leaf energy reserves in the form of soluble sugars and starch, leading to the hypothesis that herbivory-induced secondary metabolite production and growth reduction may be linked through a carbohydrate-based resource trade-off. In order to test the above hypothesis, we measured leaf carbohydrates and plant growth in seven genetically engineered Nicotiana attenuata genotypes that are deficient in one or several major herbivore-induced, jasmonate-dependent defensive secondary metabolites and proteins. Furthermore, we manipulated gibberellin and jasmonate signaling, and quantified the impact of these phytohormones on secondary metabolite production, sugar accumulation and growth. Simulated herbivore attack by Manduca sexta specifically reduced leaf sugar concentrations and growth in a jasmonate-dependent manner. These effects were similar or even stronger in defenseless genotypes with intact jasmonate signaling. Gibberellin complementation rescued carbohydrate accumulation and growth in induced plants without impairing the induction of defensive secondary metabolites. These results are consistent with a hormonal antagonism model rather than a resource-cost model to explain the negative relationship between herbivory-induced defenses, leaf energy reserves and growth.

Topics: Acetates; Animals; Carbohydrate Metabolism; Carbon; Cyclopentanes; Gibberellins; Herbivory; Manduca; Nicotiana; Oxylipins; Plant Leaves; Plant Proteins; Plant Shoots; Plants, Genetically Modified; Secondary Metabolism; Signal Transduction

In plants, cis-jasmone (CJ) is synthesized from α-linolenic acid (LA) via two biosynthetic pathways using jasmonic acid (JA) and iso-12-oxo-phytodienoic acid (iso-OPDA) as key intermediates. However, there have been no reports documenting CJ production by microorganisms. In the present study, the production of fungal-derived CJ by Lasiodiplodia theobromae was observed for the first time, although this production was not observed for Botrytis cinerea, Verticillium longisporum, Fusarium oxysporum, Gibberella fujikuroi, and Cochliobolus heterostrophus. To investigate the biosynthetic pathway of CJ in L. theobromae, administration experiments using [18,18,18-

Topics: Acetates; Ascomycota; Biosynthetic Pathways; Cyclopentanes; Deuterium; Fatty Acids, Unsaturated; Metabolome; Oxylipins

Jasmonic acid (JA) is a critical hormonal regulator of plant growth and defense. To advance our understanding of the architecture and dynamic regulation of the JA gene regulatory network, we performed a high-resolution RNA-seq time series of methyl JA-treated

Topics: Acetates; Animals; Arabidopsis; Base Sequence; Cyclopentanes; DNA, Plant; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Regulatory Networks; Genes, Plant; Insecta; Multigene Family; Nucleotide Motifs; Oxylipins; Time Factors; Transcription Factors; Transcription, Genetic

Sesquiterpenes are one of the most important defensive secondary metabolite components of agarwood. Agarwood, which is a product of the Aquilaria sinensis response to external damage, is a fragrant and resinous wood that is widely used in traditional medicines, incense and perfume. We previously reported that jasmonic acid (JA) plays an important role in promoting agarwood sesquiterpene biosynthesis and induces expression of the sesquiterpene synthase ASS1, which is a key enzyme that is responsible for the biosynthesis of agarwood sesquiterpenes in A. sinensis. However, little is known about this molecular regulation mechanism. Here, we characterized a basic helix-loop-helix transcription factor, AsMYC2, from A. sinensis as an activator of ASS1 expression. AsMYC2 is an immediate-early jasmonate-responsive gene and is co-induced with ASS1. Using a combination of yeast one-hybrid assays and chromatin immunoprecipitation analyses, we showed that AsMYC2 bound the promoter of ASS1 containing a G-box motif. AsMYC2 activated expression of ASS1 in tobacco epidermis cells and up-regulated expression of sesquiterpene synthase genes (TPS21 and TPS11) in Arabidopsis, which was also promoted by methyl jasmonate. Our results suggest that AsMYC2 participates in the regulation of agarwood sesquiterpene biosynthesis in A. sinensis by controlling the expression of ASS1 through the JA signaling pathway.

Topics: Acetates; Alkyl and Aryl Transferases; Arabidopsis; Cyclopentanes; Gene Expression Regulation, Plant; Helix-Loop-Helix Motifs; Oxylipins; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Sesquiterpenes; Thymelaeaceae; Transcription Factors

Plants employ two layers of defence that differ with respect to cell death: pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI). In our previous work, we have comparatively mapped the molecular events in a cell system derived from the wild American grape Vitis rupestris, where cell death-independent defence can be triggered by PAMP flg22, whereas the elicitor Harpin activates a cell death-related ETI-like response. Both defence responses overlapped with respect to early events, such as calcium influx, apoplastic alkalinisation, oxidative burst, mitogen-activated protein kinase (MAPK) signalling, activation of defence-related genes and accumulation of phytoalexins. However, timing and amplitude of early signals differed. In the current study, we address the role of jasmonates (JAs) as key signalling compounds in hypersensitive cell death. We find, in V. rupestris, that jasmonic acid and its bioactive conjugate jasmonoyl-isoleucine (JA-Ile) rapidly accumulate in response to flg22 but not in response to Harpin. However, Harpin can induce programmed cell death, whereas exogenous methyl jasmonate (MeJA) fails to do so, although both signals induce a similar response of defence genes. Also in a second cell line from V. vinifera cv. 'Pinot Noir', where Harpin cannot activate cell death and where flg22 fails to induce JA and JA-Ile, defence genes are activated in a similar manner. These findings indicate that the signal pathway culminating in cell death must act independently from the events culminating in the accumulation of toxic stilbenes.

Topics: Acetates; Bacterial Proteins; Cell Death; Cell Line; Cell Survival; Cyclopentanes; Flagellin; Gene Expression Regulation, Plant; Isoleucine; Oxylipins; Plant Proteins; Salicylic Acid; Stilbenes; Transcription, Genetic; Vitis

Plant hormones play a vital role in plant immune responses. However, in contrast to the relative wealth of information on hormone-mediated immunity in dicot plants, little information is available on monocot-virus defense systems. We used a high-throughput-sequencing approach to compare the global gene expression of Rice black-streaked dwarf virus (RBSDV)-infected rice plants with that of healthy plants. Exogenous hormone applications and transgenic rice were used to test RBSDV infectivity and pathogenicity. Our results revealed that the jasmonic acid (JA) pathway was induced while the brassinosteroid (BR) pathway was suppressed in infected plants. Foliar application of methyl jasmonate (MeJA) or brassinazole (BRZ) resulted in a significant reduction in RBSDV incidence, while epibrassinolide (BL) treatment increased RBSDV infection. Infection studies using coi1-13 and Go mutants demonstrated JA-mediated resistance and BR-mediated susceptibility to RBSDV infection. A mixture of MeJA and BL treatment resulted in a significant reduction in RBSDV infection compared with a single BL treatment. MeJA application efficiently suppressed the expression of BR pathway genes, and this inhibition depended on the JA coreceptor OsCOI1. Collectively, our results reveal that JA-mediated defense can suppress the BR-mediated susceptibility to RBSDV infection.

Topics: Acetates; Brassinosteroids; Cyclopentanes; Disease Susceptibility; Gene Expression Regulation, Plant; Genes, Plant; Oryza; Oxylipins; Plant Diseases; Plant Immunity; Plant Leaves; Plant Proteins; Plant Viruses; Signal Transduction; Stress, Physiological; Transcription, Genetic

Rice ratooning is practiced in many rice-growing countries for achieving increased rice production with limited labour input. Here, we report that attack by insect herbivores, or treatment with a defense signaling compound in parent plants, can prime anti-herbivore defense responses in subsequent ratoon plants. We compared the defense responses of rice ratoons generated from parent plants that had been either infested by Cnaphalocrocis medinalis (rice leaffolder, LF) caterpillars or treated with methyl jasmonate (MeJA) during vegetative growth, with ratoons generated from control parent plants. Ratoon plants generated from parents receiving prior LF infestation or MeJA treatment exhibited higher jasmonic acid (JA) levels, as well as elevated levels of transcripts of defense-related genes associated with JA signaling. In addition, elevated activities of peroxidase, polyphenol oxidase and trypsin protease inhibitor were observed, as well as enhanced resistance towards subsequent LF infestation. Pre-priming of ratoon defense responses was significantly reduced in plants where expression of OsAOS (allene oxide synthase, involved in JA biosynthesis) or OsCOI1 (CORONATINE INSENSITIVE1, involved in JA perception) was inhibited by RNA interference. Our results indicate that herbivore exposure or MeJA treatment in rice parent plants enhances anti-herbivore resistance in subsequently generated ratoons through priming of JA-mediated defenses.

Topics: Acetates; Animals; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Genes, Plant; Herbivory; Larva; Lepidoptera; Oryza; Oxylipins; Plant Diseases; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Protease Inhibitors; RNA, Messenger; Transcription, Genetic

Plant defenses inducible by herbivorous arthropods can determine performance of subsequent feeding herbivores. We investigated how infestation of tomato (Solanum lycopersicum) plants with the Western flower thrips (Frankliniella occidentalis) alters host plant suitability and foraging decisions of their conspecifics. We explored the role of delayed-induced jasmonic acid (JA)-mediated plant defense responses in thrips preference by using the tomato mutant def-1, impaired in JA biosynthesis. In particular, we investigated the effect of thrips infestation on trichome-associated tomato defenses. The results showed that when offered a choice, thrips preferred non-infested plants over infested wild-type plants, while no differences were observed in def-1. Exogenous application of methyl jasmonate restored the repellency effect in def-1. Gene expression analysis showed induction of the JA defense signaling pathway in wild-type plants, while activating the ethylene signaling pathway in both genotypes. Activation of JA defenses led to increases in type-VI leaf glandular trichome densities in the wild type, augmenting the production of trichome-associated volatiles, i.e. terpenes. Our study revealed that plant-mediated intraspecific interactions between thrips are determined by JA-mediated defenses in tomato. We report that insects can alter not only trichome densities but also the allelochemicals produced therein, and that this response might depend on the magnitude and/or type of the induction.

Topics: Acetates; Animals; Biological Assay; Cyclopentanes; Ethylenes; Feeding Behavior; Gene Expression Regulation, Plant; Herbivory; Monoterpenes; Mutation; Oxylipins; Plant Diseases; Plant Immunity; Plant Leaves; Plant Proteins; Sesquiterpenes; Solanum lycopersicum; Terpenes; Thysanoptera; Trichomes

TIFY proteins are plant-specific proteins containing TIFY, JAZ, PPD and ZML subfamilies. A total of 50, 54 and 28 members of the TIFY gene family in three cultivated cotton species-Gossypium hirsutum, Gossypium barbadense and Gossypium arboretum-were identified, respectively. The results of phylogenetic analysis showed that these TIFY genes were divided into eight clusters. The different clusters of gene family members often have similar gene structures, including the number of exons. The results of quantitative reverse transcription polymerase chain reaction (qRT-PCR) showed that different JAZ genes displayed distinct expression patterns in the leaves of upland cotton under treatment with Gibberellin (GA), methyl jasmonate (MeJA), Jasmonic acid (JA) and abscisic acid (ABA). Different groups of JAZ genes exhibited different expression patterns in cotton leaves infected with Verticillium dahliae. The results of the comparative analysis of TIFY genes in the three cultivated species will be useful for understanding the involvement of these genes in development and stress resistance in cotton.

Topics: Acetates; Cyclopentanes; DNA Methylation; Evolution, Molecular; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Genome-Wide Association Study; Genome, Plant; Gossypium; Multigene Family; Oxylipins; Phylogeny; Regulatory Elements, Transcriptional; Repressor Proteins; Transcription Factors; Transcriptome

Jasmonic acid (JA) and related metabolites play a key role in plant defense and growth. JA carboxyl methyltransferase (JMT) may be involved in plant defense and development by methylating JA to methyl jasmonate (MeJA) and thus influencing the concentrations of JA and related metabolites. However, no JMT gene has been well characterized in monocotyledon defense and development at the molecular level. After we cloned a rice JMT gene, OsJMT1, whose encoding protein was localized in the cytosol, we found that the recombinant OsJMT1 protein catalyzed JA to MeJA. OsJMT1 is up-regulated in response to infestation with the brown planthopper (BPH; Nilaparvata lugens). Plants in which OsJMT1 had been overexpressed (oe-JMT plants) showed reduced height and yield. These oe-JMT plants also exhibited increased MeJA levels but reduced levels of herbivore-induced JA and jasmonoyl-isoleucine (JA-Ile). The oe-JMT plants were more attractive to BPH female adults but showed increased resistance to BPH nymphs, probably owing to the different responses of BPH female adults and nymphs to the changes in levels of H2 O2 and MeJA in oe-JMT plants. These results indicate that OsJMT1, by altering levels of JA and related metabolites, plays a role in regulating plant development and herbivore-induced defense responses in rice.

Topics: Acetates; Cyclopentanes; Gene Expression Regulation, Plant; Herbivory; Isoleucine; Methyltransferases; Oryza; Oxylipins; Plant Proteins; Plants, Genetically Modified

The plant Artemisia annua is well known due to the production of artemisinin, a sesquiterpene lactone that is widely used in malaria treatment. Phytohormones play important roles in plant secondary metabolism, such as jasmonic acid (JA), which can induce artemisinin biosynthesis in A. annua. Nevertheless, the JA-inducing mechanism remains poorly understood. The expression of gene AaMYC2 was rapidly induced by JA and AaMYC2 binds the G-box-like motifs within the promoters of gene CYP71AV1 and DBR2, which are key structural genes in the artemisinin biosynthetic pathway. Overexpression of AaMYC2 in A. annua significantly activated the transcript levels of CYP71AV1 and DBR2, which resulted in an increased artemisinin content. By contrast, artemisinin content was reduced in the RNAi transgenic A. annua plants in which the expression of AaMYC2 was suppressed. Meanwhile, the RNAi transgenic A. annua plants showed lower sensitivity to methyl jasmonate treatment than the wild-type plants. These results demonstrate that AaMYC2 is a positive regulator of artemisinin biosynthesis and is of great value in genetic engineering of A. annua for increased artemisinin production.

Topics: Acetates; Artemisia annua; Artemisinins; Biosynthetic Pathways; Cyclopentanes; Gene Expression; Oxylipins; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; RNA Interference; Transcription Factors

Jasmonic acid (JA) is an important plant hormone involved in regulation of many aspects of plant growth and development including secondary metabolism and JASMONATE ZIM-DOMAIN (JAZ) proteins are key components in JA signal processes. In this study, two new JAZ genes named SmJAZ3 and SmJAZ9 were cloned from S. miltiorrhiza hairy roots and characterized. Expression profiles under methyl jasmonate (MJ) treatment revealed that SmJAZ3 and SmJAZ9 were both MJ-responsive. Subcellular localization assay showed that SmJAZ3 was located in nucleus while SmJAZ9 was preferentially in nucleus. Expression of SmJAZ3 and SmJAZ9 in S. miltiorrhiza hairy roots differently affected the production of tanshinone. Over-expression of SmJAZ3 or SmJAZ9 in hairy roots produced lower level of tanshinone compared with the control, tanshinone production was as low as 0.077 mg/g DW in line SmJAZ3-3 and 0.266 mg/g DW in line SmJAZ9-22. Whereas, down-regulation of SmJAZs enhanced tanshione production, the content of tanshinone increased to 2.48 fold in anti-SmJAZ3-3 line, and 1.35-fold in anti-SmJAZ9-23 line. Our work indicated that SmJAZ3 and SmJAZ9 are involved in regulation of tanshinone biosynthesis and act as repressive transcriptional regulators in the JA signaling pathway, which paves the way to further dissect molecular mechanism in details in the future.

Topics: Abietanes; Acetates; Arabidopsis; Arabidopsis Proteins; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Cloning, Molecular; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Phylogeny; Plant Growth Regulators; Plant Roots; Repressor Proteins; Salvia miltiorrhiza; Sequence Analysis, DNA

Agarwood, a highly valuable resinous and fragrant heartwood of Aquilaria plants, is widely used in traditional medicines, incense and perfume. Only when Aquilaria trees are wounded by external stimuli do they form agarwood sesquiterpene defensive compounds. Therefore, understanding the signaling pathway of wound-induced agarwood formation is important. Jasmonic acid (JA) is a well-characterized molecule that mediates a plant's defense response and secondary metabolism. However, little is known about the function of endogenous JA in agarwood sesquiterpene biosynthesis. Here, we report that heat shock can up-regulate the expression of genes in JA signaling pathway, induce JA production and the accumulation of agarwood sesquiterpene in A. sinensis cell suspension cultures. A specific inhibitor of JA, nordihydroguaiaretic acid (NDGA), could block the JA signaling pathway and reduce the accumulation of sesquiterpene compounds. Additionally, compared to SA and H2O2, exogenously supplied methyl jasmonate has the strongest stimulation effect on the production of sesquiterpene compounds. These results clearly demonstrate the central induction role of JA in heat-shock-induced sesquiterpene production in A. sinensis.

Topics: Acetates; Cell Culture Techniques; Cyclopentanes; Gene Expression Regulation, Plant; Heat-Shock Proteins; Heat-Shock Response; Hot Temperature; Masoprocol; Oxylipins; Plant Cells; Plant Proteins; Secondary Metabolism; Sesquiterpenes; Signal Transduction; Thymelaeaceae

Dutch elm disease (DED), caused by three fungal species in the genus Ophiostoma, is the most devastating disease of both native European and North American elm trees. Although many tolerant cultivars have been identified and released, the tolerance mechanisms are not well understood and true resistance has not yet been achieved. Here we show that the expression of disease-responsive genes in reactions leading to tolerance or susceptibility is significantly differentiated within the first 144 hours post-inoculation (hpi). Analysis of the levels of endogenous plant defense molecules such as jasmonic acid (JA) and salicylic acid (SA) in tolerant and susceptible American elm saplings suggested SA and methyl-jasmonate as potential defense response elicitors, which was further confirmed by field observations. However, the tolerant phenotype can be best characterized by a concurrent induction of JA and disease-responsive genes at 96 hpi. Molecular investigations indicated that the expression of fungal genes (i.e. cerato ulmin) was also modulated by endogenous SA and JA and this response was unique among aggressive and non-aggressive fungal strains. The present study not only provides better understanding of tolerance mechanisms to DED, but also represents a first, verified template for examining simultaneous transcriptomic changes during American elm-fungus interactions.

Topics: Acetates; Cyclopentanes; Disease Susceptibility; Fungal Proteins; Gene Expression Regulation, Fungal; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Immune Tolerance; Molecular Sequence Annotation; Ophiostoma; Oxylipins; Phenotype; Plant Diseases; Plant Proteins; Salicylic Acid; Time Factors; Ulmus; Virulence

Elicitation is a cheaper and socially acceptable tool for improving plant food functionality. Our objective was to optimize the treatment doses of the elicitors: methyl jasmonate (MeJA), jasmonic acid (JA) and DL-methionine (MET), in order to find a successful and feasible treatment to produce broccoli and radish sprouts with enhanced levels of health-promoting glucosinolates. Also a priming of seeds as a novel strategy to trigger the glucosinolates content was carried out with water (control), MeJA (250μM), JA (250μM) and MET (10mM) before the elicitor exogenous treatment. The results showed that almost all treatments could enhance effectively the total glucosinolates content in the sprouts, achieving the most significant increases from 34% to 100% of increase in broccoli and from 45% to 118% of increase in radish sprouts after MeJA priming and treatments. Consequently, our work demonstrates the feasibility of using elicitors, such as plant stress hormones, by priming and exogenously, as a way of increase the phytochemical profile of these sprouts to enhance their consumption in the diet.

Topics: Acetates; Brassica; Cyclopentanes; Glucosinolates; Oxylipins; Plant Growth Regulators; Raphanus; Seeds

The jasmonic acid (JA) signaling pathway plays key roles in a diverse array of plant development, reproduction, and responses to biotic and abiotic stresses. Most of our understanding of the JA signaling pathway derives from the dicot model plant Arabidopsis thaliana, while corresponding knowledge in wheat is somewhat limited. In this study, the expression of 41 genes implicated in the JA signaling pathway has been assessed on 10 day-old bread wheat seedlings, 24 h, 48 h, and 72 h after methyl-jasmonate (MeJA) treatment using quantitative real-time PCR. The examined genes have been previously reported to be involved in JA biosynthesis and catabolism, JA perception and signaling, and pathogen defense in wheat shoots and roots. This study provides evidence to suggest that the effect of MeJA treatment is more prominent in shoots than roots of wheat seedlings, and substantial regulation of the JA pathway-dependent defense genes occurs at 72 h after MeJA treatment. Results show that the expression of 22 genes was significantly affected by MeJA treatment in wheat shoots. However, only PR1.1 and PR3 were significantly differentially expressed in wheat roots, both at 24 h post-MeJA treatment, with other genes showing large variation in their gene expression in roots. While providing marker genes on JA signaling in wheat, future work may focus on elucidating the regulatory function of JA-modulated transcription factors, some of which have well-studied potential orthologs in Arabidopsis.

Topics: Acetates; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Genetic Markers; Oxylipins; Plant Roots; Plant Shoots; Signal Transduction; Triticum

Jasmonates (JAs) are recognized as essential regulators in response to environmental stimuli and plant development. Carrot is an Apiaceae vegetable with great value and undergoes significant size changes over the course of plant growth. However, JA accumulation and its potential roles in carrot growth remain unclear. Here, methyl JA (MeJA) levels and expression profiles of JA-related genes were analyzed in carrot roots and leaves at five developmental stages. MeJA levels in the roots and leaves were the highest at the first stage and decreased as carrot growth proceeded. Transcript levels of several JA-related genes (Dc13-LOX1, Dc13-LOX2, DcAOS, DcAOC, DcOPR2, DcOPR3, DcOPCL1, DcJAR1, DcJMT, DcCOI1, DcJAZ1, DcJAZ2, DcMYC2, DcCHIB/PR3, DcLEC, and DcVSP2) were not well correlated with MeJA accumulation during carrot root and leaf development. In addition, some JA-related genes (DcJAR1, DcJMT, DcCOI1, DcMYC2, and DcVSP2) showed differential expression between roots and leaves. These results suggest that JAs may regulate carrot plant growth in stage-dependent and organ-specific manners. Our work provides novel insights into JA accumulation and its potential roles during carrot growth and development.

Topics: Acetates; Cyclopentanes; Daucus carota; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes, Plant; Models, Biological; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Roots; Signal Transduction

Seed predators can cause mass ingestion of larger seed populations. As well, herbivorous arthropods attempt to attack etiolated seedlings and chose the apical hook for ingestion, aimed at dropping the cotyledons for later consumption. Etiolated seedlings, as we show here, have established an efficient mechanism of protecting their Achilles' heel against these predators, however. Evidence is provided for a role of jasmonic acid (JA) in this largely uncharacterized plant-herbivore interaction during skotomorphogenesis and that this comprises the temporally and spatially tightly controlled synthesis of a cysteine protease inhibitors of the Kunitz family. Interestingly, the same Kunitz protease inhibitor was found to be expressed in flowers of Arabidopsis where endogenous JA levels are high for fertility. Because both the apical hook and inflorescences were preferred isopod targets in JA-deficient plants that could be rescued by exogenously administered JA, our data identify a JA-dependent mechanism of plant arthropod deterrence that is recalled in different organs and at quite different times of plant development.

Topics: Acetates; Animals; Arabidopsis; Arthropods; Cyclopentanes; Etiolation; Gene Expression Regulation, Plant; Herbivory; Oxylipins; Seedlings

In this study, we highlight the effects of methyl jasmonate (MeJa) on cystocarp development in the red macroscopic alga Grateloupia imbricata. In G. imbricata, jasmonate release is related to the reproductive state, as fertile thalli (i.e., those that have cystocarps) released significant amounts of this volatile compound (1.27 ± 0.20 mM · mg fw

Topics: Acetates; Cyclopentanes; Genetic Pleiotropy; Oxylipins; Plant Growth Regulators; Reactive Oxygen Species; Reproduction; Rhodophyta

Gentiana macrophylla, a medicinal plant with significant pharmacological properties, contains the bioactive compound gentiopicroside. Methyl jasmonate (MeJA) is an effective elicitor for enhancing the production of such compounds. However, little is known about MeJA-mediated biosynthesis of gentiopicroside. We investigated this phenomenon as well as gene expression profiles to determine the molecular mechanisms for MeJA-mediated gentiopicroside biosynthesis and regulation in G. macrophylla. Our HPLC results showed that Gentiana macrophylla seedlings exposed to MeJA had significantly higher concentrations of gentiopicroside when compared with control plants. We used RNA sequencing to compare transcriptional profiles in seedlings treated for 5 d with either 0 μmol L-1 MeJA (C) or 250 μmol L-1 MeJA (M5) and detected differentially expressed genes (DEGs). In total, 77,482 unique sequences were obtained from approximately 34 million reads. Of these, 48,466 (57.46%) sequences were annotated based on BLASTs performed against public databases. We identified 5,206 DEGs between the C and M5 samples, including genes related to the α-lenolenic acid degradation pathway, JA signaling pathway, and gentiopicroside biosynthesis. Expression of numerous enzyme genes in the glycolysis pathway was significantly up-regulated. Many genes encoding transcription factors (e.g. ERF, bHLH, MYB, and WRKY) also responded to MeJA elicitation. Rapid acceleration of the glycolysis pathway that supplies precursors for IPP biosynthesis and up-regulates the expression of enzyme genes in that IPP pathway are probably most responsible for MeJA stimulation of gentiopicroside synthesis. Our qRT-PCR results showed that the expression profiles of 12 gentiopicroside biosynthesis genes were consistent with the RNA-Seq data. These results increase our understanding about how the gentiopicroside biosynthesis pathway in G. macrophylla responds to MeJA.

Topics: Acetates; alpha-Linolenic Acid; Biosynthetic Pathways; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Gentiana; Glycolysis; Iridoid Glucosides; Molecular Sequence Annotation; Oxylipins; Real-Time Polymerase Chain Reaction; Reproducibility of Results; Secondary Metabolism; Seedlings; Sequence Analysis, RNA; Signal Transduction; Transcription Factors; Transcription, Genetic; Transcriptome; Up-Regulation

Jasmonates (JAs) play important roles in plant growth, development and defense. Comprehensive metabolomics profiling of plants under JA treatment provides insights into the interaction and regulation network of plant hormones. Here we applied high resolution mass spectrometry based metabolomics approach on Arabidopsis wild type and JA synthesis deficiency mutant opr3. The effects of exogenous MeJA treatment on the metabolites of opr3 were investigated. More than 10000 ion signals were detected and more than 2000 signals showed significant variation in different genotypes and treatment groups. Multivariate statistic analyses (PCA and PLS-DA) were performed and a differential compound library containing 174 metabolites with high resolution precursor ion-product ions pairs was obtained. Classification and pathway analysis of 109 identified compounds in this library showed that glucosinolates and tryptophan metabolism, amino acids and small peptides metabolism, lipid metabolism, especially fatty acyls metabolism, were impacted by endogenous JA deficiency and exogenous MeJA treatment. These results were further verified by quantitative reverse transcription PCR (RT-qPCR) analysis of 21 related genes involved in the metabolism of glucosinolates, tryptophan and α-linolenic acid pathways. The results would greatly enhance our understanding of the biological functions of JA.

Topics: Acetates; alpha-Linolenic Acid; Arabidopsis; Arabidopsis Proteins; Cluster Analysis; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Glucosinolates; Lipid Metabolism; Metabolome; Oxidoreductases; Oxylipins; Peptides; Principal Component Analysis; Real-Time Polymerase Chain Reaction; Tryptophan

Plants have evolved diverse defense metabolites as adaptations to biotic and abiotic stresses. The defense alkaloid nicotine is produced in Nicotiana tabacum (tobacco) and its biosynthesis is elicited by jasmonates in the roots. At least seven jasmonate-responsive genes that encode transcription factors of the Ethylene Response Factor (ERF) family are clustered at the nicotine-regulatory locus NICOTINE2 (NIC2) in the tobacco genome. A subset of the NIC2-locus ERFs and their homologs, including ERF189 and ERF199, have been shown to be most effective in controlling nicotine biosynthetic pathway genes. Herein reported is that the ERF genes of this group, other than ERF189 and ERF199, were strongly induced by NaCl in tobacco hairy roots, although salt stress had no effect on expression of nicotine biosynthesis genes. Abscisic acid and osmotic stress also increased expression of a subset of these NaCl-inducible ERF genes. Promoter expression analysis in transgenic tobacco hairy roots confirmed that while methyl jasmonate (MJ) activated the promoters of ERF29, ERF210 and ERF199, salt stress up-regulated the promoters of only ERF29 and ERF210, but not ERF199. The protein biosynthesis inhibitor cycloheximide induced expression of the ERFs, and simultaneous addition of MJ and cycloheximide showed synergistic effects. These results indicate that, after several gene duplication events, the NIC2-locus ERFs and possibly their homologs appear to have diverged in their responses to jasmonates and various environmental inputs, including salt stress, and may have evolved to regulate distinct metabolic processes and cellular responses.

Topics: Abscisic Acid; Acetates; Cyclopentanes; Ethylenes; Nicotiana; Nicotine; Oxylipins; Plant Proteins; Plant Roots; Sodium Chloride; Transcription Factors

Andrographolide is a prominent secondary metabolite found in Andrographis paniculata that exhibits enormous pharmacological effects. In spite of immense value, the normal biosynthesis of andrographolide results in low amount of the metabolite. To induce the biosynthesis of andrographolide, we attempted elicitor-induced activation of andrographolide biosynthesis in cell cultures of A. paniculata. This was carried out by using methyl jasmonate (MeJA) as an elicitor. Among the various concentrations of MeJA tested at different time periods, 5 µM MeJA yielded 5.25 times more andrographolide content after 24 h of treatment. The accumulation of andrographolide was correlated with the expression level of known regulatory genes (hmgs, hmgr, dxs, dxr, isph and ggps) of mevalonic acid (MVA) and 2-C-methyl-d-erythritol-4-phosphate (MEP) pathways. These results established the involvement of MeJA in andrographolide biosynthesis by inducing the transcription of its biosynthetic pathways genes. The coordination of isph, ggps and hmgs expression highly influenced the andrographolide biosynthesis.

Topics: Acetates; Andrographis; Biosynthetic Pathways; Cells, Cultured; Cyclopentanes; Diterpenes; Gene Expression Regulation, Plant; Genes, Plant; Oxylipins; Real-Time Polymerase Chain Reaction

Tomato plants colonised with the arbuscular mycorrhizal (AM) fungus Glomus fasciculatum show systemic induced resistance to the foliar pathogen Alternaria alternata, as observed in interactions of other AM-colonised plants with a range of pathogens. The role of jasmonic (JA) and salicylic (SA) acid in expression of this mycorrhiza-induced resistance (MIR) against A. alternata was studied by measuring: (i) activity of enzymes reported to be involved in their biosynthesis, namely lipoxygenase (LOX) and phenylammonia lyase (PAL); and (ii) levels of methyl jasmonate (MeJA) and SA. Transcript abundance of some defence genes associated with JA and SA response pathways were also studied. Both LOX and PAL activity increased twofold in response to pathogen application to control plants. AM-colonised plants had three-fold higher LOX activity compared to control plants, but unlike controls, this did not increase further in response to pathogen application. Higher LOX activity in AM-colonised plants correlated with four-fold higher MeJA in leaves of AM-colonised plants compared to controls. Treatment of plants with the JA biosynthesis inhibitor salicylhydroxamic acid (SHAM) led to 50% lower MeJA in both control and AM-colonised plants and correlated with increased susceptibility to A. alternata, suggesting a causal role for JA in expression of MIR against the pathogen. Genes involved in JA biosynthesis (OPR3) and response (COI1) showed six- and 42-fold higher expression, respectively, in leaves of AM-colonised plants compared to controls. AM-colonised plants also showed increased expression of the SA response gene PR1 and that of the wound-inducible polypeptide prosystemin. Our results suggest that the systemic increase in JA in response to AM colonisation plays a key role in expression of MIR against A. alternata.

Topics: Acetates; Alternaria; Cyclopentanes; Disease Resistance; Genes, Plant; Glomeromycota; Lipoxygenase; Lyases; Mycorrhizae; Oxylipins; Plant Diseases; Plant Leaves; Plant Proteins; Salicylic Acid; Solanum lycopersicum

Anthocyanin and proanthocyanidin (PA) are important secondary metabolites and beneficial to human health. Their biosynthesis is induced by jasmonate (JA) treatment and regulated by MYB transcription factors (TFs). However, which and how MYB TFs regulate this process is largely unknown in apple. In this study, MdMYB9 and MdMYB11 which were induced by methyl jasmonate (MeJA) were functionally characterized. Overexpression of MdMYB9 or MdMYB11 promoted not only anthocyanin but also PA accumulation in apple calluses, and the accumulation was further enhanced by MeJA. Subsequently, yeast two-hybrid, pull-down and bimolecular fluorescence complementation assays showed that both MYB proteins interact with MdbHLH3. Moreover, Jasmonate ZIM-domain (MdJAZ) proteins interact with MdbHLH3. Furthermore, chromatin immunoprecipitation-quantitative PCR and yeast one-hybrid assays demonstrated that both MdMYB9 and MdMYB11 bind to the promoters of ANS, ANR and LAR, whereas MdbHLH3 is recruited to the promoters of MdMYB9 and MdMYB11 and regulates their transcription. In addition, transient expression assays indicated that overexpression of MdJAZ2 inhibits the recruitment of MdbHLH3 to the promoters of MdMYB9 and MdMYB11. Our findings provide new insight into the mechanism of how MeJA regulates anthocyanin and PA accumulation in apple.

Topics: Acetates; Anthocyanins; Biosynthetic Pathways; Cyclopentanes; Flavonoids; Gene Expression Regulation, Plant; Genes, Plant; Malus; Models, Biological; Oxylipins; Plant Proteins; Plants, Genetically Modified; Proanthocyanidins; Promoter Regions, Genetic; Protein Binding

Polyamines are involved in key developmental processes and stress responses. Copper amine oxidases oxidize the polyamine putrescine (Put), producing an aldehyde, ammonia, and hydrogen peroxide (H2O2). The Arabidopsis (Arabidopsis thaliana) amine oxidase gene At4g14940 (AtAO1) encodes an apoplastic copper amine oxidase expressed at the early stages of vascular tissue differentiation in roots. Here, its role in root development and xylem differentiation was explored by pharmacological and forward/reverse genetic approaches. Analysis of the AtAO1 expression pattern in roots by a promoter::green fluorescent protein-β-glucuronidase fusion revealed strong gene expression in the protoxylem at the transition, elongation, and maturation zones. Methyl jasmonate (MeJA) induced AtAO1 gene expression in vascular tissues, especially at the transition and elongation zones. Early protoxylem differentiation was observed upon MeJA treatment along with Put level decrease and H2O2 accumulation in wild-type roots, whereas Atao1 loss-of-function mutants were unresponsive to the hormone. The H2O2 scavenger N,N(1)-dimethylthiourea reversed the MeJA-induced early protoxylem differentiation in wild-type seedlings. Likewise, Put, which had no effect on Atao1 mutants, induced early protoxylem differentiation in the wild type, this event being counteracted by N,N(1)-dimethylthiourea treatment. Consistently, AtAO1-overexpressing plants showed lower Put levels and early protoxylem differentiation concurrent with H2O2 accumulation in the root zone where the first protoxylem cells with fully developed secondary wall thickenings are found. These results show that the H2O2 produced via AtAO1-driven Put oxidation plays a role in MeJA signaling leading to early protoxylem differentiation in root.

Topics: Acetates; Amine Oxidase (Copper-Containing); Arabidopsis; Arabidopsis Proteins; Cell Differentiation; Copper; Cyclopentanes; Gene Expression Regulation, Plant; Hydrogen Peroxide; Mutation; Oxylipins; Plant Roots; Plants, Genetically Modified; Putrescine; Thiourea; Xylem

Inducible defenses that provide enhanced resistance to insect attack are nearly universal in plants. The defense-signaling cascade is mediated by the synthesis, movement, and perception of jasmonate (JA) and the interaction of this signaling molecule with other plant hormones and messengers. To explore how the interaction of JA and ethylene influences induced defenses, we employed the never-ripe (Nr) tomato mutant, which exhibits a partial block in ethylene perception, and the defenseless (def1) mutant, which is deficient in JA biosynthesis. The defense gene proteinase inhibitor (PIN2) was used as marker to compare plant responses. The Nr mutant showed a normal wounding response with PIN2 induction, but the def1 mutant did not. As expected, methyl JA (MeJA) treatment restored the normal wound response in the def1 mutant. Exogenous application of MeJA increased resistance to Helicoverpa zea, induced defense gene expression, and increased glandular trichome density on systemic leaves. Exogenous application of ethephon, which penetrates tissues and decomposes to ethylene, resulted in increased H. zea growth and interfered with the wounding response. Ethephon treatment also increased salicylic acid in systemic leaves. These results indicate that while JA plays the main role in systemic induced defense, ethylene acts antagonistically in this system to regulate systemic defense.

Topics: Acetates; Animals; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Herbivory; Moths; Organophosphorus Compounds; Oxylipins; Plant Growth Regulators; Plant Leaves; Solanum lycopersicum; Trichomes

Systemic resistance is induced by pathogens and confers protection against a broad range of pathogens. Recent studies have indicated that salicylic acid (SA) derivative methyl salicylate (MeSA) serves as a long-distance phloem-mobile systemic resistance signal in tobacco, Arabidopsis, and potato. However, other experiments indicate that jasmonic acid (JA) is a critical mobile signal. Here, we present evidence suggesting both MeSA and methyl jasmonate (MeJA) are essential for systemic resistance against Tobacco mosaic virus (TMV), possibly acting as the initiating signals for systemic resistance. Foliar application of JA followed by SA triggered the strongest systemic resistance against TMV. Furthermore, we use a virus-induced gene-silencing-based genetics approach to investigate the function of JA and SA biosynthesis or signaling genes in systemic response against TMV infection. Silencing of SA or JA biosynthetic and signaling genes in Nicotiana benthamiana plants increased susceptibility to TMV. Genetic experiments also proved the irreplaceable roles of MeSA and MeJA in systemic resistance response. Systemic resistance was compromised when SA methyl transferase or JA carboxyl methyltransferase, which are required for MeSA and MeJA formation, respectively, were silenced. Moreover, high-performance liquid chromatography-mass spectrometry analysis indicated that JA and MeJA accumulated in phloem exudates of leaves at early stages and SA and MeSA accumulated at later stages, after TMV infection. Our data also indicated that JA and MeJA could regulate MeSA and SA production. Taken together, our results demonstrate that (Me)JA and (Me)SA are required for systemic resistance response against TMV.

Topics: Acetates; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Gene Silencing; Genes, Reporter; Nicotiana; Oxylipins; Phloem; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Salicylates; Salicylic Acid; Signal Transduction; Tobacco Mosaic Virus

Several biotic elicitors have been used in Brassicaceae species to enhance their phytochemical quality. However, there is no comparison between elicitors under controlled growth conditions. In order to draw general conclusions about the use of elicitors to enrich ready-to-eat sprouts in health-promoting glucosinolates, the aim of this study was to unveil the effect of the phytohormones methyl jasmonate (25 μM), jasmonic acid (150 μM), and salicylic acid (100 μM), the oligosaccharides glucose (277 mM) and sucrose (146 mM), and the amino acid dl-methionine (5 mM) as elicitors over 8-day sprouting Brassica oleraceae (broccoli), Brassica napus (rutabaga cabbage), Brassica rapa (turnip), and Raphanus sativus (China rose radish and red radish), representative species high in glucosinolates previously studied. Results indicated that the phytohormones methyl jasmonate and jasmonic acid and the sugars acted as effective elicitors, increasing the total glucosinolate contents of the sprouts, particularly, glucoraphanin (from 183 to 294 mg·100 g(-1) in MeJA-treated broccoli sprouts), glucoraphenin (from 33 to 124 mg·100 g(-1) and from 167 to 227 mg·100 g(-1) in MeJA-treated China rose radish and red radish, respectively), and glucobrassicin (from 23.4 to 91.0 mg·100 g(-1) and from 29.6 to 186 mg·100 g(-1) in MeJA-treated turnip and rutabaga sprouts, respectively).

Topics: Acetates; Brassicaceae; Cyclopentanes; Glucosinolates; Oxylipins; Plant Growth Regulators; Salicylic Acid

• RuBPCase activase (RCA), an abundant photosynthetic protein, is strongly down-regulated in response to Manduca sexta's oral secretion (OS) in Nicotiana attenuata. RCA-silenced plants are impaired not only in photosynthetic capacity and growth, but also in jasmonic acid-isoleucine (JA-Ile) signaling, and herbivore resistance mediated by JA-Ile-dependent defense traits. These responses are consistent with a resource-based growth-defense trade-off. • As JA + Ile supplementation of OS restored wild-type (WT) levels of JA-Ile, defenses and resistance to M. sexta, but OS supplemented individually with JA or Ile did not, the JA-Ile deficiency of RCA-silenced plants could not be attributed to lower JA or Ile pools or JAR4/6 conjugating activity. Similar levels of JA-Ile derivatives after OS elicitation indicated unaltered JA-Ile turnover, and lower levels of other JA conjugates ruled out competition from other conjugation reactions. • RCA-silenced plants accumulated more methyl jasmonate (MeJA) after OS elicitation, which corresponded to increased jasmonate methyltransferase (JMT) activity. RCA silencing phenocopies JMT overexpression, wherein elevated JMT activity redirects OS-elicited JA flux towards inactive MeJA, creating a JA sink which depletes JA-Ile and its associated defense responses. • Hence, RCA plays an additional non-photosynthetic role in attenuating JA-mediated defenses and their associated costs, potentially allowing plants to anticipate resource-based constraints on growth before they actually occur.

Topics: Acetates; Animals; Cyclopentanes; Gene Silencing; Herbivory; Isoleucine; Manduca; Methylation; Methyltransferases; Nicotiana; Oxylipins; Plant Proteins; Signal Transduction

Plants have evolved an elaborate signaling network to ensure an appropriate level of immune response to meet the differing demands of developmental processes. Previous research has demonstrated that DELLA proteins physically interact with JASMONATE ZIM-DOMAIN1 (JAZ1) and dynamically regulate the interaction of the gibberellin (GA) and jasmonate (JA) signaling pathways. However, whether and how the JAZ1-DELLA regulatory node is regulated at the transcriptional level in plants under normal growth conditions or during pathogen infection is not known. Here, we demonstrate multiple functions of cotton (Gossypium barbadense) GbWRKY1 in the plant defense response and during development. Although GbWRKY1 expression is induced rapidly by methyl jasmonate and infection by Verticillium dahliae, our results show that GbWRKY1 is a negative regulator of the JA-mediated defense response and plant resistance to the pathogens Botrytis cinerea and V. dahliae. Under normal growth conditions, GbWRKY1-overexpressing lines displayed GA-associated phenotypes, including organ elongation and early flowering, coupled with the down-regulation of the putative targets of DELLA. We show that the GA-related phenotypes of GbWRKY1-overexpressing plants depend on the constitutive expression of Gossypium hirsutum GhJAZ1. We also show that GhJAZ1 can be transactivated by GbWRKY1 through TGAC core sequences, and the adjacent sequences of this binding site are essential for binding specificity and affinity to GbWRKY1, as revealed by dual-luciferase reporter assays and electrophoretic mobility shift assays. In summary, our data suggest that GbWRKY1 is a critical regulator mediating the plant defense-to-development transition during V. dahliae infection by activating JAZ1 expression.

Topics: Acetates; Cyclopentanes; Disease Resistance; Down-Regulation; Gene Expression Regulation, Plant; Gibberellins; Gossypium; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Verticillium

Jasmonates (JAs) are important phytohormones that regulate a wide range of plant processes including growth, development, senescence, and defense. Jasmonate ZIM-domain (JAZ) proteins are repressors in JA signaling. In Arabidopsis thaliana, 12 JAZ encoding genes were identified, but only a few have been studied in detail. In this study, we focused on characterizing the molecular networks involving JAZ2 and JAZ7. To understand the phenotypes and elucidate the regulatory functions of JAZ2 and JAZ7, shoot and root tissues from wild type (WT), jaz2, and jaz7 were harvested for RNA sequencing and metabolomics. Distinct changes of transcripts and metabolites in JA biosynthesis, primary and specialized metabolism, and oxidative stress were observed among the three genotypes. In particular, many defense or stress-associated metabolites and specialized metabolites were increased in response to methyl jasmonate (MeJA) treatment. Most importantly, these changes were subjected to quantitative modulation by the JAZ proteins at both transcriptional and metabolic levels, the degree of which may control resource allocation between growth and defense. This study not only reveals MeJA-induced molecular reprogramming but also demonstrates the functions of JAZ proteins as key regulators in fine-tuning JA signal transduction.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Chromatography, Liquid; Cyclopentanes; Gas Chromatography-Mass Spectrometry; Gene Expression Profiling; Gene Expression Regulation, Plant; Glucose; Mass Spectrometry; Metabolome; Metabolomics; Molecular Sequence Data; Mutation; Oxylipins; Plant Growth Regulators; Plant Roots; Plant Shoots; Repressor Proteins; Sequence Homology, Amino Acid; Signal Transduction; Transcriptome

Jasmonic acid and its derivatives (jasmonates [JAs]) play central roles in floral development and maturation. The binding of jasmonoyl-L-isoleucine (JA-Ile) to the F-box of CORONATINE INSENSITIVE1 (COI1) is required for many JA-dependent physiological responses, but its role in anthesis and pollinator attraction traits remains largely unexplored. Here, we used the wild tobacco Nicotiana attenuata, which develops sympetalous flowers with complex pollination biology, to examine the coordinating function of JA homeostasis in the distinct metabolic processes that underlie flower maturation, opening, and advertisement to pollinators. From combined transcriptomic, targeted metabolic, and allometric analyses of transgenic N. attenuata plants for which signaling deficiencies were complemented with methyl jasmonate, JA-Ile, and its functional homolog, coronatine (COR), we demonstrate that (1) JA-Ile/COR-based signaling regulates corolla limb opening and a JA-negative feedback loop; (2) production of floral volatiles (night emissions of benzylacetone) and nectar requires JA-Ile/COR perception through COI1; and (3) limb expansion involves JA-Ile-induced changes in limb fresh mass and carbohydrate metabolism. These findings demonstrate a master regulatory function of the JA-Ile/COI1 duet for the main function of a sympetalous corolla, that of advertising for and rewarding pollinator services. Flower opening, by contrast, requires JA-Ile signaling-dependent changes in primary metabolism, which are not compromised in the COI1-silenced RNA interference line used in this study.

Topics: Abscisic Acid; Acetates; Acetone; Amino Acids; Animals; Arabidopsis Proteins; Cyclopentanes; Esterases; Flowers; Gene Expression Profiling; Gene Expression Regulation, Plant; Indenes; Isoleucine; Manduca; Metabolic Networks and Pathways; Methyltransferases; Models, Biological; Nicotiana; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Growth Regulators; Plant Nectar; Plant Proteins; Plants, Genetically Modified; Pollination; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference

Anthocyanins are critical for plants. It is shown that the expression of genes encoding the key enzymes such as dihydroflavonol 4-reductase (DFR), UDP-Glc: flavonoid 3-O-glucosyltransferase (UF3GT), and leucoanthocyanidin dioxygenase (LDOX) in anthocyanin biosynthesis pathway is regulated by MYB75, a R2R3 MYB transcription factor. The production of anthocyanin is known to be promoted by jasmonic acid (JA) in light but not in darkness. The photoreceptors cryptochrome 1 (CRY1), phytochrome B (phyB), and phytochrome A (phyA) are also shown to mediate light promotion of anthocyanin accumulation, respectively, whereas their downstream factor COP1, a master negative regulator of photomorphogensis, represses anthocyanin accumulation. However, whether JA coordinates with photoreceptors in the regulation of anthocyanin accumulation is unknown. Here, we show that under far-red light, JA promotes anthocyanin accumulation in a phyA signaling pathway-dependent manner. The phyA mutant is hyposensitive to jasmonic acid analog methyl jasmonic acid (MeJA) under far-red light. The dominant mutant of MYB75, pap1-D, accumulates significantly higher levels of anthocyanin than wild type under far-red light, whereas knockdown of MYBs (MYB75, MYB90, MYB113, and MYB114) through RNAi significantly reduces MeJA promotion of anthocyanin accumulation. The phyA pap1-D double mutant shows reduced responsiveness to MeJA, similar to phyA mutant under far-red light. In darkness, a mutant allele of cop1, cop1-4, shows enhanced responsiveness to MeJA, but pap1-D mutant is barely responsive to MeJA. Upon MeJA application, the cop1-4 pap1-D double mutant accumulates considerably higher levels of anthocyanin than cop1-4 in darkness. Protein studies indicate that MYB75 protein is stabilized by white light and far-red light. Further gene expression studies suggest that MeJA promotes the expression of DFR, UF3GT, and LDOX genes in a phyA- and MYB75-dependent manner under far-red light. Our findings suggest that JA promotion of anthocyanin accumulation under far-red light is dependent on phyA signaling pathway, consisting of phyA, COP1, and MYB75.

Topics: Acetates; Anthocyanins; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Darkness; Gene Expression; Genes, Plant; Light; Mutation; Oxylipins; Pancreatitis-Associated Proteins; Photoreceptors, Plant; Phytochrome A; Plants, Genetically Modified; Signal Transduction; Transcription Factors; Ubiquitin-Protein Ligases

Jasmonic acid (JA) signalling plays a central role in plant defences against necrotrophic pathogens and herbivorous insects, which afflict both roots and shoots. This pathway is also activated following the interaction with beneficial microbes that may lead to induced systemic resistance. Activation of the JA signalling pathway via application of methyl jasmonate (MeJA) alters the composition of carbon containing compounds released by roots, which are implicated as key determinants of rhizosphere microbial community structure. In this study, we investigated the influence of the JA defence signalling pathway activation in Arabidopsis thaliana on the structure of associated rhizosphere bacterial communities using 16S rRNA gene amplicon pyrosequencing. Application of MeJA did not directly influence bulk soil microbial communities but significant changes in rhizosphere community composition were observed upon activation of the jasmonate signalling pathway. Our results suggest that JA signalling may mediate plant-bacteria interactions in the soil upon necrotrophic pathogen and herbivorous insect attacks.

Topics: Acetates; Arabidopsis; Bacteria; Biodiversity; Cyclopentanes; Oxylipins; Rhizosphere; Signal Transduction

Interactions between phytohormones play important roles in the regulation of plant growth and development, but knowledge of the networks controlling hormonal relationships, such as between oxylipins and auxins, is just emerging. Here, we report the transcriptional regulation of two Arabidopsis YUCCA genes, YUC8 and YUC9, by oxylipins. Similar to previously characterized YUCCA family members, we show that both YUC8 and YUC9 are involved in auxin biosynthesis, as demonstrated by the increased auxin contents and auxin-dependent phenotypes displayed by gain-of-function mutants as well as the significantly decreased indole-3-acetic acid (IAA) levels in yuc8 and yuc8/9 knockout lines. Gene expression data obtained by qPCR analysis and microscopic examination of promoter-reporter lines reveal an oxylipin-mediated regulation of YUC9 expression that is dependent on the COI1 signal transduction pathway. In support of these findings, the roots of the analyzed yuc knockout mutants displayed a reduced response to methyl jasmonate (MeJA). The similar response of the yuc8 and yuc9 mutants to MeJA in cotyledons and hypocotyls suggests functional overlap of YUC8 and YUC9 in aerial tissues, while their function in roots shows some specificity, probably in part related to different spatio-temporal expression patterns of the two genes. These results provide evidence for an intimate functional relationship between oxylipin signaling and auxin homeostasis.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cotyledon; Cyclopentanes; Gene Expression Regulation, Plant; Gene Knockout Techniques; Homeostasis; Hypocotyl; Indoleacetic Acids; Mixed Function Oxygenases; Mutation; Oxygenases; Oxylipins; Phenotype; Plant Components, Aerial; Plant Growth Regulators; Plant Roots; Plants, Genetically Modified; Signal Transduction

Antagonism between the defense hormones salicylic acid (SA) and jasmonic acid (JA) plays a central role in the modulation of the plant immune signaling network, but the molecular mechanisms underlying this phenomenon are largely unknown. Here, we demonstrate that suppression of the JA pathway by SA functions downstream of the E3 ubiquitin-ligase Skip-Cullin-F-box complex SCF(COI1), which targets JASMONATE ZIM-domain transcriptional repressor proteins (JAZs) for proteasome-mediated degradation. In addition, neither the stability nor the JA-induced degradation of JAZs was affected by SA. In silico promoter analysis of the SA/JA crosstalk transcriptome revealed that the 1-kb promoter regions of JA-responsive genes that are suppressed by SA are significantly enriched in the JA-responsive GCC-box motifs. Using GCC:GUS lines carrying four copies of the GCC-box fused to the β-glucuronidase reporter gene, we showed that the GCC-box motif is sufficient for SA-mediated suppression of JA-responsive gene expression. Using plants overexpressing the GCC-box binding APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors ERF1 or ORA59, we found that SA strongly reduces the accumulation of ORA59 but not that of ERF1. Collectively, these data indicate that the SA pathway inhibits JA signaling downstream of the SCF(COI1)-JAZ complex by targeting GCC-box motifs in JA-responsive promoters via a negative effect on the transcriptional activator ORA59.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Binding Sites; Cyclopentanes; Gene Expression Regulation, Plant; Homeodomain Proteins; Nuclear Proteins; Nucleotide Motifs; Oxylipins; Peptide Termination Factors; Plants, Genetically Modified; Promoter Regions, Genetic; Salicylic Acid; Signal Transduction; Transcription Factors

Abscisic acid (ABA) plays a central role in seed dormancy and transcriptional regulation of genes coding for ABA biosynthetic and degradation enzymes is responsible for control of ABA content. However, little is known about signalling both before and after ABA regulation, in particular, how environmental signals are perceived and transduced. We are interested in these processes in cereal grains, particularly in relation to the development of strategies for controlling pre-harvest sprouting in barley and wheat. Our previous studies have indicated possible components of dormancy control and here we present evidence that blue light, nitric oxide (NO) and jasmonate are major controlling elements in wheat grain. Using microarray and pharmacological studies, we have found that blue light inhibits germination in dormant grain and that methyl jasmonate (MJ) and NO counteract this effect by reducing dormancy. We also present evidence that NO and jasmonate play roles in dormancy control in vivo. ABA was reduced by MJ and this was accompanied by reduced levels of expression of TaNCED1 and increased expression of TaABA8'OH-1 compared with dormant grain. Similar changes were caused by after-ripening. Analysis of global gene expression showed that although jasmonate and after-ripening caused important changes in gene expression, the changes were very different. While breaking dormancy, MJ had only a small number of target genes including gene(s) encoding beta-glucosidase. Our evidence indicates that NO and MJ act interdependently in controlling reduction of ABA and thus the demise of dormancy.

Topics: Abscisic Acid; Acetates; Cyclopentanes; Gene Expression Regulation, Plant; Germination; Light; Nitric Oxide; Oxylipins; Plant Dormancy; Triticum

Singlet oxygen (¹O₂) is a reactive oxygen species that can function as a stress signal in plant leaves leading to programmed cell death. In microalgae, ¹O₂-induced transcriptomic changes result in acclimation to ¹O₂. Here, using a chlorophyll b-less Arabidopsis thaliana mutant (chlorina1 [ch1]), we show that this phenomenon can also occur in vascular plants. The ch1 mutant is highly photosensitive due to a selective increase in the release of ¹O₂ by photosystem II. Under photooxidative stress conditions, the gene expression profile of ch1 mutant leaves very much resembled the gene responses to ¹O₂ reported in the Arabidopsis mutant flu. Preexposure of ch1 plants to moderately elevated light intensities eliminated photooxidative damage without suppressing ¹O₂ formation, indicating acclimation to ¹O₂. Substantial differences in gene expression were observed between acclimation and high-light stress: A number of transcription factors were selectively induced by acclimation, and contrasting effects were observed for the jasmonate pathway. Jasmonate biosynthesis was strongly induced in ch1 mutant plants under high-light stress and was noticeably repressed under acclimation conditions, suggesting the involvement of this hormone in ¹O₂-induced cell death. This was confirmed by the decreased tolerance to photooxidative damage of jasmonate-treated ch1 plants and by the increased tolerance of the jasmonate-deficient mutant delayed-dehiscence2.

Topics: Acclimatization; Acetates; Arabidopsis; Arabidopsis Proteins; Biosynthetic Pathways; Chlorophyll; Cyclopentanes; Gene Expression Regulation, Plant; Light; Lipid Peroxidation; Mutation; Oligonucleotide Array Sequence Analysis; Oxidation-Reduction; Oxygenases; Oxylipins; Photosystem II Protein Complex; Plant Growth Regulators; Plant Leaves; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; Singlet Oxygen; Transcriptome

Plant cell culture represents an alternative source for producing high-value secondary metabolites including paclitaxel (Taxol®), which is mainly produced in Taxus and has been widely used in cancer chemotherapy. The phytohormone methyl jasmonate (MeJA) can significantly increase the production of paclitaxel, which is induced in plants as a secondary metabolite possibly in defense against herbivores and pathogens. In cell culture, MeJA also elicits the accumulation of paclitaxel; however, the mechanism is still largely unknown.. To obtain insight into the global regulation mechanism of MeJA in the steady state of paclitaxel production (7 days after MeJA addition), especially on paclitaxel biosynthesis, we sequenced the transcriptomes of MeJA-treated and untreated Taxus × media cells and obtained ∼ 32.5 M high quality reads, from which 40,348 unique sequences were obtained by de novo assembly. Expression level analysis indicated that a large number of genes were associated with transcriptional regulation, DNA and histone modification, and MeJA signaling network. All the 29 known genes involved in the biosynthesis of terpenoid backbone and paclitaxel were found with 18 genes showing increased transcript abundance following elicitation of MeJA. The significantly up-regulated changes of 9 genes in paclitaxel biosynthesis were validated by qRT-PCR assays. According to the expression changes and the previously proposed enzyme functions, multiple candidates for the unknown steps in paclitaxel biosynthesis were identified. We also found some genes putatively involved in the transport and degradation of paclitaxel. Potential target prediction of miRNAs indicated that miRNAs may play an important role in the gene expression regulation following the elicitation of MeJA.. Our results shed new light on the global regulation mechanism by which MeJA regulates the physiology of Taxus cells and is helpful to understand how MeJA elicits other plant species besides Taxus.

Topics: Acetates; Cell Line; Cells, Cultured; Computational Biology; Cyclopentanes; Databases, Genetic; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; High-Throughput Nucleotide Sequencing; MicroRNAs; Molecular Sequence Annotation; Oxylipins; Paclitaxel; Plant Cells; Plant Growth Regulators; Reproducibility of Results; RNA, Messenger; Taxus; Terpenes; Transcriptome

The effects of methyl jasmonate and jasmonic acid on galanthamine production, phenolic acid content and growth of Leucojum aestivum L. shoot culture, cultivated in submerged conditions were investigated. The best time-point for addition of elicitors was during the exponential phase of the culture growth. The maximal contents of galanthamine and lycorine (226.9 μg/flask and 491.4 μg/flask, 1.36 and 1.67-fold higher compared to the control, respectively) were achieved after elicitation with jasmonic acid, whereas the elicitation with methyl jasmonte resulted in maximal accumulation of phenolic acids. It was demonstrated that the boosting effect of jasmonic acid on Amaryllidacea alkaloid biosynthesis was due to induction of the activity of tyrosine decarboxylase, whereas methyl jasmonate stimulates the biosynthesis of phenolic acids by inducing mainly the activity of phenylalanine ammonia-lyase.

Topics: Acetates; Cyclopentanes; Galantamine; Liliaceae; Oxylipins; Phenylalanine Ammonia-Lyase; Plant Shoots

This study investigated the roles of jasmonates in the regulation of sorgoleone accumulation and the expression of genes involved in sorgoleone biosynthesis in sorghum roots. Both methyl jasmonate (MeJa) and jasmonic acid (JA) substantially promoted root hair formation, secondary root development, root weight, and sorgoleone accumulation in sorghum roots. Sorgoleone content varied widely depending on the concentration of JA or MeJa and the duration of their application. Root weight and sorgoleone accumulation were highest after the application of JA or MeJa at a concentration of 5.0 μM, and then declined with increasing concentrations of jasmonates. At 5.0 μM, JA and MeJa increased sorgoleone content by 4.1 and 3.4-fold, respectively. Transcript accumulation was apparent for all genes, particularly for the O-methyltransferase 3 gene, which increased in expression levels up to 8.1-fold after a 36-h exposure to MeJa and 3.5-fold after a 48-h exposure to JA. The results of this study pave the way for more effective biosynthesis of sorgoleone, an important and useful allelochemical obtained from a variety of plant species.

Topics: Acetates; Benzoquinones; Chromatography, High Pressure Liquid; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Lipids; Oxylipins; Plant Growth Regulators; Plant Roots; Real-Time Polymerase Chain Reaction; Sorghum; Time Factors

A GC/MS method with monolithic material sorptive extraction (MMSE) pretreatment was developed to determine contents of the enantiomers of jasmonic acid and methyl jasmonate in flowers. To optimize MMSE extraction, several MMSE parameters were investigated, including extraction temperature, extraction time, and extraction solvent. Under the optimal conditions, extraction efficiency was good. Using the selected-ion monitoring mode, the limit of detection (LOD, S/N = 3) for methyl jasmonates was 0.257 ng/mL. The limit of quantitation (LOQ, S/N = 10) was 0.856 ng/mL. The linearity range was 1-100 ng/mL. The average recovery of methyl jasmonate at lower concentration was 116.8% (2 ng/mL). The relative standard deviation of methyl jasmonate contents determined within the linear range of detection was less than or equal to 15% of the mean determined level. The proposed method is rapid, sensitive, and competently applied to the determination of jasmonic acid and methyl jasmonate enantiomers in flowers.

Topics: Acetates; China; Cyclopentanes; Flowers; Oxylipins; Pheromones; Plant Extracts; Stereoisomerism

Methyl jasmonate is a metabolite known to be produced by many plants and has roles in diverse biological processes. It is biosynthesized by the action of S-adenosyl-l-methionine:jasmonic acid carboxyl methyltransferase (JMT), which belongs to the SABATH family of methyltransferases. Herein is reported the isolation and biochemical characterization of a JMT gene from black cottonwood (Populus trichocarpa). The genome of P. trichocarpa contains 28 SABATH genes (PtSABATH1 to PtSABATH28). Recombinant PtSABATH3 expressed in Escherichia coli showed the highest level of activity with jasmonic acid (JA) among carboxylic acids tested. It was therefore renamed PtJMT1. PtJMT1 also displayed activity with benzoic acid (BA), with which the activity was about 22% of that with JA. PtSABATH2 and PtSABATH4 were most similar to PtJMT1 among all PtSABATHs. However, neither of them had activity with JA. The apparent Km values of PtJMT1 using JA and BA as substrate were 175μM and 341μM, respectively. Mutation of Ser-153 and Asn-361, two residues in the active site of PtJMT1, to Tyr and Ser respectively, led to higher specific activity with BA than with JA. Homology-based structural modeling indicated that substrate alignment, in which Asn-361 is involved, plays a role in determining the substrate specificity of PtJMT1. In the leaves of young seedlings of black cottonwood, the expression of PtJMT1 was induced by plant defense signal molecules methyl jasmonate and salicylic acid and a fungal elicitor alamethicin, suggesting that PtJMT1 may have a role in plant defense against biotic stresses. Phylogenetic analysis suggests that PtJMT1 shares a common ancestor with the Arabidopsis JMT, and functional divergence of these two apparent JMT orthologs has occurred since the split of poplar and Arabidopsis lineages.

Topics: Acetates; Alamethicin; Benzoic Acid; Biocatalysis; Catalytic Domain; Cyclopentanes; Escherichia coli; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Hydrogen-Ion Concentration; Kinetics; Metals; Methyltransferases; Multigene Family; Mutation; Oxylipins; Phylogeny; Plant Growth Regulators; Plant Proteins; Populus; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Salicylic Acid; Substrate Specificity; Temperature

Pak choi plants (Brassica rapa ssp. chinensis) were treated with different signaling molecules methyl jasmonate, jasmonic acid, linolenic acid, and methyl salicylate and were analyzed for specific changes in their glucosinolate profile. Glucosinolate levels were quantified using HPLC-DAD-UV, with focus on induction of indole glucosinolates and special emphasis on 1-methoxy-indol-3-ylmethyl glucosinolate. Furthermore, the effects of the different signaling molecules on indole glucosinolate accumulation were analyzed on the level of gene expression using semi-quantitative realtime RT-PCR of selected genes. The treatments with signaling molecules were performed on sprouts and mature leaves to determine ontogenetic differences in glucosinolate accumulation and related gene expression. The highest increase of indole glucosinolate levels, with considerable enhancement of the 1-methoxy-indol-3-ylmethyl glucosinolate content, was achieved with treatments of sprouts and mature leaves with methyl jasmonate and jasmonic acid. This increase was accompanied by increased expression of genes putatively involved in the indole glucosinolate biosynthetic pathway. The high levels of indole glucosinolates enabled the plant to preferentially produce the respective breakdown products after tissue damage. Thus, pak choi plants treated with methyl jasmonate or jasmonic acid, are a valuable tool to analyze the specific protection functions of 1-methoxy-indole-3-carbinole in the plants defense strategy in the future.

Topics: Acetates; Brassica; Chromatography, High Pressure Liquid; Cyclopentanes; Gene Expression Regulation; Glucosinolates; Indoles; Oxylipins; Plant Leaves; Plant Proteins

Larix gmelinii is a dominant tree species in China's boreal forests and plays an important role in the coniferous ecosystem. It is also one of the most economically important tree species in the Chinese timber industry due to excellent water resistance and anti-corrosion of its wood products. Unfortunately, in Northeast China, L. gmelinii often suffers from serious attacks by diseases and insects. The application of exogenous volatile semiochemicals may induce and enhance its resistance against insect or disease attacks; however, little is known regarding the genes and molecular mechanisms related to induced resistance.. We performed de novo sequencing and assembly of the L. gmelinii transcriptome using a short read sequencing technology (Illumina). Chemical defenses of L. gmelinii seedlings were induced with jasmonic acid (JA) or methyl jasmonate (MeJA) for 6 hours. Transcriptomes were compared between seedlings induced by JA, MeJA and untreated controls using a tag-based digital gene expression profiling system. In a single run, 25,977,782 short reads were produced and 51,157 unigenes were obtained with a mean length of 517 nt. We sequenced 3 digital gene expression libraries and generated between 3.5 and 5.9 million raw tags, and obtained 52,040 reliable reference genes after removing redundancy. The expression of disease/insect-resistance genes (e.g., phenylalanine ammonialyase, coumarate 3-hydroxylase, lipoxygenase, allene oxide synthase and allene oxide cyclase) was up-regulated. The expression profiles of some abundant genes under different elicitor treatment were studied by using real-time qRT-PCR.The results showed that the expression levels of disease/insect-resistance genes in the seedling samples induced by JA and MeJA were higher than those in the control group. The seedlings induced with MeJA elicited the strongest increases in disease/insect-resistance genes.. Both JA and MeJA induced seedlings of L. gmelinii showed significantly increased expression of disease/insect-resistance genes. MeJA seemed to have a stronger induction effect than JA on expression of disease/insect-resistance related genes. This study provides sequence resources for L. gmelinii research and will help us to better understand the functions of disease/insect-resistance genes and the molecular mechanisms of secondary metabolisms in L. gmelinii.

Topics: Acetates; Chromosome Mapping; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Gene Ontology; Genes, Plant; Larix; Molecular Sequence Annotation; Open Reading Frames; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Seedlings; Transcriptional Activation; Transcriptome; Up-Regulation

Methyl jasmonate (MeJA) elicits protective effects as form of plant response to abiotic stress. However, related studies on plant response to metal stress are insufficient. This study aimed to examine the effects of MeJA on growth and physiological responses of Capsicum frutescens seedlings exposed to cadmium (Cd) stress. The study was performed in an artificial climate chamber. Results showed that 50 mg L⁻¹ Cd significantly impaired the growth of the seedlings by increasing leaf MDA content and decreasing chlorophyll b. These effects were significantly mitigated by MeJA at low concentrations (0.1 µmol L⁻¹). The dry weights of different plant parts, chlorophyll content, and leaf catalase and ascorbate peroxidase activities were increased by a low MeJA concentration (0.1 µmol L⁻¹) but were decreased by a high MeJA concentration (1000 µmol L⁻¹). Significant increases in endogenous jasmonic acid were observed at 48 h after the samples were treated with Cd and 0.1 µmol L⁻¹ MeJA. These results suggested that low exogenous MeJA concentrations exhibited protective effects on the growth and physiology of C. frutescens seedlings under Cd stress.

Topics: Acetates; Ascorbate Peroxidases; Cadmium; Capsicum; Catalase; Chlorophyll; Cyclopentanes; Hydrogen Peroxide; Lipid Peroxidation; Oxylipins; Plant Leaves; Seedlings; Soil Pollutants; Stress, Physiological

MYC2, a basic helix-loop-helix (bHLH) transcription factor, is a key regulator in the activation of jasmonate (JA) response. However, the molecular details of MYC2 involving in methyl jasmonate (MeJA)-induced chilling tolerance of fruit remain largely unclear. In the present work, two MYC2 genes, MaMYC2a and MaMYC2b, and one homolog of the inducer of the C-repeat-binding factor (CBF) gene, MaICE1 were isolated and characterized from banana fruit. MaMYC2s and MaICE1 were found to be all localized in the nucleus. In addition, the proline-rich domain (PRD) and the acidic domain (AD) in the N-terminus were important for the transcriptional activation of MaMYC2 in yeast cells. Unlike MaICE1's constitutive expression, MaMYC2a and MaMYC2b were induced rapidly following MeJA treatment during cold storage. Moreover, protein-protein interaction analysis confirmed that MaMYC2s interacted with MaICE1. The expression of ICE-CBF cold-responsive pathway genes including MaCBF1, MaCBF2, MaCOR1, MaKIN2, MaRD2 and MaRD5 was also significantly induced by MeJA. Taken together, our work provides strong evidence that MaMYC2 is involved in MeJA-induced chilling tolerance in banana fruit through physically interacting and likely functionally coordinating with MaICE1, revealing a novel mechanism for ICE1 in response to cold stress as well as during development of induced chilling tolerance.

Topics: Acetates; Amino Acid Sequence; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Cold Temperature; Cyclopentanes; Fruit; Gene Expression Regulation, Plant; Molecular Sequence Data; Musa; Oxylipins; Plant Proteins; Protein Structure, Tertiary; Real-Time Polymerase Chain Reaction; Sequence Analysis, DNA

Hormones play pivotal roles in regulating plant development, growth, and stress responses, and cross-talk among different hormones fine-tunes various aspects of plant physiology. Jasmonic acid (JA) is important for plant defense against herbivores and necrotic fungi and also regulates flower development; in addition, Arabidopsis mutants over-producing JA usually have stunted stems and wound-induced jasmonates suppress Arabidopsis growth, suggesting that JA is also involved in stem elongation. Gibberellins (GAs) promote stem and leaf growth and modulate seed germination, flowering time, and the development of flowers, fruits, and seeds. However, little is known about the interaction between the JA and GA pathways. Two calcium-dependent protein kinases, CDPK4 and CDPK5, are important suppressors of JA accumulation in a wild tobacco species, Nicotiana attenuata. The stems of N. attenuata silenced in CDPK4 and CDPK5 (irCDPK4/5 plants) had dramatically increased levels of JA and exhibited stunted elongation and had very high contents of secondary metabolites. Genetic analysis indicated that the high JA levels in irCDPK4/5 stems accounted for the suppressed stem elongation and the accumulation of secondary metabolites. Supplementation of GA(3) to irCDPK4/5 plants largely restored normal stem growth to wild-type levels. Measures of GA levels indicated that over-accumulation of JA in irCDPK4/5 stems inhibited the biosynthesis of GAs. Finally, we show that JA antagonizes GA biosynthesis by strongly inhibiting the transcript accumulation of GA20ox and possibly GA13ox, the key genes in GA production, demonstrating that high JA levels antagonize GA biosynthesis in stems.

Topics: Acetates; Anatomy, Cross-Sectional; Cyclopentanes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Gene Silencing; Genes, Plant; Genetic Complementation Test; Gibberellins; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Proteins; Plant Stems; Pollination; Promoter Regions, Genetic; Protein Kinases; Transcription, Genetic

The formation of auxin conjugates is one of the important regulatory mechanisms for modulating IAA action. Several auxin-responsive GH3 genes encode IAA-amide synthetases that are involved in the maintenance of hormonal homeostasis by conjugating excess IAA to amino acids. Recently, the data have revealed novel regulatory functions of several GH3 proteins in plant growth, organ development, fruit ripening, light signaling, abiotic stress tolerance and plant defense responses. Indole-3-acetyl-aspartate (IAA-Asp) synthetase catalyzing IAA conjugation to aspartic acid in immature seeds of pea (Pisum sativum L.) was purified and characterized during our previous investigations. In this study, we examined the effect of auxin and other plant hormones (ABA, GA, kinetin, JA, MeJA, SA), different light conditions (red, far-red, blue, white light), and auxinic herbicides (2,4-D, Dicamba, Picloram) on the expression of a putative GH3 gene and IAA-amide synthesizing activity in 10-d-old pea seedlings. Quantitative RT-PCR analysis indicated that the PsGH3-5 gene, weakly expressed in control sample, was visibly induced in response to all plant hormones, different light wavelengths and the auxinic herbicides tested. Protein A immunoprecipitation/gel blot analysis using anti-AtGH3.5 antibodies revealed a similar pattern of changes on the protein levels in response to all treatments. IAA-amide synthetase activity determined with aspartate as a substrate, not detectable in control seedlings, was positively affected by a majority of treatments. Based on these results, we suggest that PsGH3-5 may control the growth and development of pea plants in a way similar to the known GH3 genes from other plant species.

Topics: 2,4-Dichlorophenoxyacetic Acid; Acetates; Cyclopentanes; Dicamba; Gene Expression Regulation, Plant; Genes, Plant; Herbicides; Kinetin; Light; Multienzyme Complexes; Oxylipins; Picloram; Pisum sativum; Plant Growth Regulators; Salicylic Acid; Seedlings

Allene oxide synthase (AOS) is the first committed step in the biosynthetic pathway of Jasmonate. In this study, a full-length cDNA of AOS gene (named as AaAOS) was cloned from Artemisia annua. The gene was 1891 bp in size containing an open reading frame (1581 bp) encoding 526 amino acids. Comparative and bioinformatic analysis revealed that the deduced protein of AaAOS was highly homologous to AOSs from other plant species. Phylogenetic analysis indicated that the protein of AaAOS belonged to the dicotyledonous group, which was consistent with the category of A. annua. Southern blot analysis revealed that it was a low-copy gene. Quantitative Real-time PCR (qRT-PCR) analysis showed that AaAOS mRNA accumulated most abundantly in leaves and flowers. The qRT-PCR analysis revealed that MeJA, ABA and ethylene treatments significantly enhanced AaAOS transcript expression.

Topics: Acetates; Amino Acid Sequence; Artemisia annua; Base Sequence; Biosynthetic Pathways; Blotting, Southern; Cloning, Molecular; Computational Biology; Cyclopentanes; DNA Primers; DNA, Complementary; Ethylenes; Flowers; Gene Expression Regulation, Plant; Intramolecular Oxidoreductases; Molecular Sequence Data; Open Reading Frames; Oxylipins; Plant Leaves; Real-Time Polymerase Chain Reaction; Sequence Analysis, DNA; Sequence Homology

We report here that disruption of function of the ω-3 FATTY ACID DESATURASE7 (FAD7) enhances plant defenses against aphids. The suppressor of prosystemin-mediated responses2 (spr2) mutation in tomato (Solanum lycopersicum), which eliminates the function of FAD7, reduces the settling behavior, survival, and fecundity of the potato aphid (Macrosiphum euphorbiae). Likewise, the antisense suppression of LeFAD7 expression in wild-type tomato plants reduces aphid infestations. Aphid resistance in the spr2 mutant is associated with enhanced levels of salicylic acid (SA) and mRNA encoding the pathogenesis-related protein P4. Introduction of the Naphthalene/salicylate hydroxylase transgene, which suppresses SA accumulation, restores wild-type levels of aphid susceptibility to spr2. Resistance in spr2 is also lost when we utilize virus-induced gene silencing to suppress the expression of NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1), a positive regulator of many SA-dependent defenses. These results indicate that FAD7 suppresses defenses against aphids that are mediated through SA and NPR1. Although loss of function of FAD7 also inhibits the synthesis of jasmonate (JA), the effects of this desaturase on aphid resistance are not dependent on JA; other mutants impaired in JA synthesis (acx1) or perception (jai1-1) show wild-type levels of aphid susceptibility, and spr2 retains aphid resistance when treated with methyl jasmonate. Thus, FAD7 may influence JA-dependent defenses against chewing insects and SA-dependent defenses against aphids through independent effects on JA synthesis and SA signaling. The Arabidopsis (Arabidopsis thaliana) mutants Atfad7-2 and Atfad7-1fad8 also show enhanced resistance to the green peach aphid (Myzus persicae) compared with wild-type controls, indicating that FAD7 influences plant-aphid interactions in at least two plant families.

Topics: Acetates; Animals; Aphids; Arabidopsis; Biosynthetic Pathways; Cyclopentanes; Disease Resistance; Fatty Acid Desaturases; Feeding Behavior; Fertility; Gene Expression Regulation, Plant; Genes, Plant; Mutation; Oxylipins; Plant Diseases; Plant Proteins; Salicylic Acid; Solanum lycopersicum; Survival Analysis; Transgenes; Up-Regulation

Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea.

Topics: Acetates; Bacterial Outer Membrane Proteins; Bacterial Proteins; Cyclopentanes; Down-Regulation; Erwinia amylovora; Gene Expression Regulation, Plant; Genotype; Host-Pathogen Interactions; Malus; Mutation; Oxylipins; Plant Diseases; Plant Immunity; Plant Leaves; Plant Proteins; RNA, Plant; Salicylic Acid; Signal Transduction; Time Factors

Plants have developed multifaceted defensive systems against adverse environmental factors. One such recognized system is the production of metabolites in plants. Jasmonic acid (JA) and its metabolite methyl jasmonate (MeJA) are known to play key roles in metabolites production. The role of MeJA as a mobile signal has been established in Arabidopsis and Solanaceae plants. However, it remains largely unclear how MeJA-based signaling is organized via its elicited metabolites. Here, we investigated the signaling ability of MeJA by means of vascular transport using Achyranthes bidentata as an experimental plant. Results showed that MeJA was transported and essentially metabolized into its active form JA-Ile in the distal undamaged leaves accompanied by emission of volatile organic compounds. Results presented and discussed therein provide convincing evidence that MeJA acts as a transportable inter-cellular mobile compound in plants self-defense scheme.

Topics: Acetates; Achyranthes; Cyclopentanes; Gene Expression Regulation, Plant; Isoleucine; Oxylipins; Plant Leaves

This study provides a desirable candidate gene resource (SmAOC) to increase the content of valuable natural products via appropriate JA pathway genetic engineering. Jasmonates (JAs) are important signal molecules in plants. They regulate transcripts of defense and secondary biosynthetic metabolite genes in response to environmental stresses. Currently, JAs are widely used as elicitors to improve the content of useful secondary metabolism in plants. Synthesis of the naturally occurring enantiomer of various jasmonates is catalyzed by allene oxide cyclase (AOC, EC 5.3.99.6). Here, we cloned and characterized the AOC gene (SmAOC) from Salvia miltiorrhiza. As expected, SmAOC expression was induced by abiotic stimuli such as methyl jasmonate (MeJA), ultraviolet radiation (UV) and low temperature (4 °C) in S. miltiorrhiza plantlets. To demonstrate whether the engineered internal JAs pool by overexpressing AOC gene could promote secondary metabolism production, the SmAOC was incorporated into S. miltiorrhiza hairy roots. The results revealed that SmAOC overexpression significant enhanced the yields of tanshinone IIA, rosmarinic acid (RA) and lithospermic acid B (LAB) in S. miltiorrhiza hairy roots. In addition, expression levels for key genes involved in the biosynthetic pathway of diterpenes and phenolic acids were also altered. These suggest that genetic manipulation of AOC would be helpful for improving the production of valuable secondary metabolites by regulating the biosynthesis of JAs.

Topics: Abietanes; Acetates; Benzofurans; Cinnamates; Cloning, Molecular; Cold Temperature; Cyclopentanes; Depsides; Diterpenes; Escherichia coli; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant; Genetic Engineering; Genetic Vectors; Hydroxybenzoates; Intramolecular Oxidoreductases; Oxylipins; Plant Roots; Rosmarinic Acid; Salvia miltiorrhiza; Transgenes; Ultraviolet Rays

Studies involving plant-nematode interactions provide an opportunity to unravel plant defense signaling in root tissues. In this study, we have characterized the roles of salicylate (SA), jasmonate (JA), ethylene (ET) and abscisic acid (ABA) in plant defense against the migratory nematode Hirschmanniella oryzae in the monocot model plant rice (Oryza sativa). Experiments with exogenous hormone applications, biosynthesis inhibition and mutant/transgenic lines were executed to test the effect on H. oryzae parasitism in rice roots. Our results demonstrate that an intact ET, JA and SA biosynthesis pathway is a prerequisite for defense against H. oryzae. By contrast, exogenous ABA treatment drastically compromised the rice defense towards this nematode. Gene expression analyses using quantitative reverse transcription polymerase chain reaction (qRT-PCR) demonstrate that the disease-inducing effect of ABA is likely to be the result of an antagonistic interaction between this hormone and the SA/JA/ET-dependent basal defense system. Collectively, in rice defense against H. oryzae, at least three pathways, namely SA, JA and ET, are important, while ABA plays a negative role in defense. Our results suggest that the balance of ABA and SA/JA/ET signaling is an important determinant for the outcome of the rice-H. oryzae interaction.

Topics: Abscisic Acid; Acetates; Animals; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Host-Parasite Interactions; Nematoda; Oryza; Oxylipins; Plant Diseases; Plant Roots; Plant Shoots; Plants, Genetically Modified; Pyridones; Reverse Transcriptase Polymerase Chain Reaction; RNA, Plant; Salicylic Acid; Signal Transduction; Transcription, Genetic; Transcriptome

We investigated what gene(s) in the plant roots have the positive role against repressing root-knot nematode (RKN) infection. We investigated the interaction between RKN infection and gene expression in the plant roots induced by methyl jasmonate (MeJA). We focused on the induced resistance response and the duration after foliar treatment with MeJA of 0.1, 0.5, 1.0, and 5.0mM at 1, 24, 48, and 72h prior to the inoculation of RKN. As a result, the foliar treatment with MeJA at 0.5mM or higher concentrations significantly reduced the infection of RKN in plants and the effect lasted for about 1 week. The repressing effect on RKN population declined to the lowest level in two weeks after MeJA treatment. The expression of proteinase inhibitors (PIs) and multicystatin (MC) were induced while the repressing effect on RKN was valid and a negative correlation was found between the expression of PIs or MC and RKN infection. In addition, when tomato plants no longer expressing MC and PIs were treated again with MeJA, the repressing effect revived. These phenomena appeared to be regardless of the existence of Mi-genes or isolate of RKN. Our results indicate that the expression level of MC and PIs may be effective as marker genes for estimating the induced resistance response against RKN infection.

Topics: Acetates; Animals; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Genetic Markers; Host-Parasite Interactions; Oxylipins; Parasite Egg Count; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Leaves; Plant Roots; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Solanum lycopersicum; Time Factors; Tylenchoidea

To clarify genetically the involvement of two Arabidopsis NADPH oxidases (AtrbohD and AtrbohF) in the jasmonic acid (JA) signaling pathway, we characterized single knockout mutants lacking either Atrboh. The accumulation of reactive oxygen species (ROS) and expression of the genes regulated by MYC2, a transcription factor involved in the JA-evoked response, were significantly suppressed by treatment with methyl JA (MeJA) in both mutants. Further experiments using knockout mutants lacking CORONATINE-INSENSITIVE1 (COI1), a master regulator of the JA-evoked response, and MYC2 indicated a possibility that the production of ROS via Atrbohs depends on the function of COI1, but not MYC2.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Cyclopentanes; Gene Expression Regulation, Plant; Gene Knockout Techniques; NADPH Oxidases; Oxylipins; Plant Growth Regulators; Reactive Oxygen Species; Signal Transduction

Viruses must create a suitable cell environment and elude defense mechanisms, which likely involves interactions with host proteins and subsequent interference with or usurpation of cellular machinery. Here, we describe a novel strategy used by plant DNA viruses (Geminiviruses) to redirect ubiquitination by interfering with the activity of the CSN (COP9 signalosome) complex. We show that geminiviral C2 protein interacts with CSN5, and its expression in transgenic plants compromises CSN activity on CUL1. Several responses regulated by the CUL1-based SCF ubiquitin E3 ligases (including responses to jasmonates, auxins, gibberellins, ethylene, and abscisic acid) are altered in these plants. Impairment of SCF function is confirmed by stabilization of yellow fluorescent protein-GAI, a substrate of the SCF(SLY1). Transcriptomic analysis of these transgenic plants highlights the response to jasmonates as the main SCF-dependent process affected by C2. Exogenous jasmonate treatment of Arabidopsis thaliana plants disrupts geminivirus infection, suggesting that the suppression of the jasmonate response might be crucial for infection. Our findings suggest that C2 affects the activity of SCFs, most likely through interference with the CSN. As SCFs are key regulators of many cellular processes, the capability of viruses to selectively interfere with or hijack the activity of these complexes might define a novel and powerful strategy in viral infections.

Topics: Acetates; Amino Acids, Cyclic; Arabidopsis; Arabidopsis Proteins; COP9 Signalosome Complex; Cullin Proteins; Cyclopentanes; DNA-Binding Proteins; Geminiviridae; Gene Expression Profiling; Gene Expression Regulation, Plant; Gibberellins; Mutation; Oxylipins; Phenotype; Plant Growth Regulators; Plant Roots; Plants, Genetically Modified; Recombinant Fusion Proteins; Ubiquitin-Protein Ligases; Ubiquitination; Ubiquitins; Viral Proteins

Jasmonates (JAs) induce leaf senescence in many plant species. The Arabidopsis F-box protein coronatine insensitive 1 (COI1) is required for various JA-regulated plant responses including plant fertility, defense responses and leaf senescence. However, the molecular basis for COI1-dependent JA-induced leaf senescence remains unknown. In our Plant Physiology paper, we identified a COI1-dependent JA-repressed protein, Rubisco activase (RCA) in Arabidopsis. Further genetic and physiological analyses showed that the COI1-dependent JA repression of RCA correlated with JA-induced leaf senescence, and that loss of RCA led to typical senescence-associated features. Therefore, we suggested that the COI1-dependent JA repression of RCA played an important role in JA-induced leaf senescence. In this addendum, we made a relatively deep discussion on RCA function in JA-induced leaf senescence and JA-mediated defense responses. We also discussed the possible role of JA in plant natural senescence.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cellular Senescence; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Plant Leaves; Plant Proteins; Plants, Genetically Modified

The plant cell wall is a dynamic and complex structure whose functional integrity is constantly being monitored and maintained during development and interactions with the environment. In response to cell wall damage (CWD), putatively compensatory responses, such as lignin production, are initiated. In this context, lignin deposition could reinforce the cell wall to maintain functional integrity. Lignin is important for the plant's response to environmental stress, for reinforcement during secondary cell wall formation, and for long-distance water transport. Here, we identify two stages and several components of a genetic network that regulate CWD-induced lignin production in Arabidopsis (Arabidopsis thaliana). During the early stage, calcium and diphenyleneiodonium-sensitive reactive oxygen species (ROS) production are required to induce a secondary ROS burst and jasmonic acid (JA) accumulation. During the second stage, ROS derived from the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D and JA-isoleucine generated by JASMONIC ACID RESISTANT1, form a negative feedback loop that can repress each other's production. This feedback loop in turn seems to influence lignin accumulation. Our results characterize a genetic network enabling plants to regulate lignin biosynthesis in response to CWD through dynamic interactions between JA and ROS.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Calcium; Cell Wall; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Plant; Lignin; Models, Biological; Mutation; Onium Compounds; Oxylipins; Phenotype; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; Seedlings; Signal Transduction

S-nitrosoglutathione reductase (GSNOR) reduces the nitric oxide (NO) adduct S-nitrosoglutathione (GSNO), an essential reservoir for NO bioactivity. In plants, GSNOR has been found to be important in resistance to bacterial and fungal pathogens, but whether it is also involved in plant-herbivore interactions was not known. Using a virus-induced gene silencing (VIGS) system, the activity of GSNOR in a wild tobacco species, Nicotiana attenuata, was knocked down and the function of GSNOR in defence against the insect herbivore Manduca sexta was examined. Silencing GSNOR decreased the herbivory-induced accumulation of jasmonic acid (JA) and ethylene, two important phytohormones regulating plant defence levels, without compromising the activity of two mitogen-activated protein kinases (MAPKs), salicylic acid-induced protein kinase (SIPK) and wound-induced protein kinase (WIPK). Decreased activity of trypsin proteinase inhibitors (TPIs) were detected in GSNOR-silenced plants after simulated M. sexta feeding and bioassays indicated that GSNOR-silenced plants have elevated susceptibility to M. sexta attack. Furthermore, GSNOR is required for methyl jasmonate (MeJA)-induced accumulation of defence-related secondary metabolites (TPI, caffeoylputrescine, and diterpene glycosides) but is not needed for the transcriptional regulation of JAZ3 (jasmonate ZIM-domain 3) and TD (threonine deaminase), indicating that GSNOR mediates certain but not all jasmonate-inducible responses. This work highlights the important role of GSNOR in plant resistance to herbivory and jasmonate signalling and suggests the potential involvement of NO in plant-herbivore interactions. Our data also suggest that GSNOR could be a target of genetic modification for improving crop resistance to herbivores.

Topics: Acetates; Aldehyde Oxidoreductases; Animals; Cyclopentanes; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Gene Silencing; Herbivory; Manduca; Mitogen-Activated Protein Kinases; Nicotiana; Oxylipins; Plant Proteins; RNA, Messenger

Lipoxygenase (LOX) catalyses oxygenation of free polyunsaturated fatty acids into oxylipins, and is a critical enzyme of the jasmonate signaling pathway. LOX has been shown to be associated with biotic and abiotic stress responses in diverse plant species, though limited data is available with respect to low temperature and the associated cues. Using rapid amplification of cDNA ends, a full-length cDNA (CjLOX) encoding lipoxygenase was cloned from apical buds of Caragana jubata, a temperate plant species that grows under extreme cold. The cDNA obtained was 2952bp long consisting of an open reading frame of 2610bp encoding 869 amino acids protein. Multiple alignment of the deduced amino acid sequence with those of other plants demonstrated putative LH2/ PLAT domain, lipoxygenase iron binding catalytic domain and lipoxygenase_2 signature sequences. CjLOX exhibited up- and down-regulation of gene expression pattern in response to low temperature (LT), abscisic acid (ABA), methyl jasmonate (MJ) and salicylic acid (SA). Among all the treatments, a strong up-regulation was observed in response to MJ. Data suggests an important role of jasmonate signaling pathway in response to LT in C. jubata.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Caragana; Cold Temperature; Cyclopentanes; Genes, Plant; Lipoxygenase; Molecular Sequence Data; Oxylipins; Phylogeny; Salicylic Acid; Sequence Alignment; Signal Transduction

Methyl jasmonate, jasmonic acid and chitosan were tested as elicitors on cell suspension cultures obtained from Vitis vinifera cv Italia to investigate their effect on stilbene production. Stilbene accumulation in the callus, grown under nonelicited conditions, was also investigated. Calli and cell suspensions were obtained in a B5 culture medium supplemented with 0.2 mg L(-1) NAA and 1 mg L(-1) KIN. Stilbene determination was achieved by HPLC/DAD/MS. Whereas callus biosynthesized only piceid, cell suspensions elicited with jasmonates produced several stilbenes, mainly viniferins. In suspended cells, methyl jasmonate and jasmonic acid were the most effective in stimulating stilbene biosynthesis, whereas chitosan was less effective; in fact, the amount of stilbenes obtained with this elicitor was not significantly different from that obtained for the control cells. The maximum production of total stilbenes was at day 20 of culture with 0.970 and 1.023 mg g(-1) DW for MeJA and JA, respectively.

Topics: Acetates; Benzofurans; Cells, Cultured; Chitosan; Cyclopentanes; Oxylipins; Plant Growth Regulators; Plant Stems; Resorcinols; Resveratrol; Stilbenes; Vitis

We have previously shown that local exposure of plants to stress results in a systemic increase in genome instability. Here, we show that UV-C-irradiated plants produce a volatile signal that triggers an increase in genome instability in neighboring nonirradiated Arabidopsis thaliana plants. This volatile signal is interspecific, as UV-C-irradiated Arabidopsis plants transmit genome destabilization to naive tobacco (Nicotiana tabacum) plants and vice versa. We report that plants exposed to the volatile hormones methyl salicylate (MeSA) or methyl jasmonate (MeJA) exhibit a similar level of genome destabilization as UV-C-irradiated plants. We also found that irradiated Arabidopsis plants produce MeSA and MeJA. The analysis of mutants impaired in the synthesis and/or response to salicylic acid (SA) and/or jasmonic acid showed that at least one other volatile compound besides MeSA and MeJA can communicate interplant genome instability. The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (npr1) mutant, defective in SA signaling, is impaired in both the production and the perception of the volatile signals, demonstrating a key role for NPR1 as a central regulator of genome stability. Finally, various forms of stress resulting in the formation of necrotic lesions also generate a volatile signal that leads to genomic instability.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Bacterial Proteins; Cyclopentanes; Gene Expression Regulation, Plant; Genome, Plant; Genomic Instability; Homologous Recombination; Membrane Proteins; Mutation; Nicotiana; Oxylipins; Plants, Genetically Modified; Salicylates; Salicylic Acid; Signal Transduction; Stress, Physiological; Tobacco Mosaic Virus; Ultraviolet Rays

Jasmonic acid (JA) is a crucial plant defence signalling substance that has recently been shown to mediate herbivory-induced root growth reduction in the ecological model species Nicotiana attenuata. To clarify whether JA-induced reduction of root growth might be a general response increasing plant fitness under biotic stress, a suite of experiments was performed with the model plant Arabidopsis thaliana. JA bursts were elicited in leaves of A. thaliana in different ways. Root growth reduction was neither induced by foliar application of herbivore oral secretions nor by direct application of methyl jasmonate to leaves. Root growth reduction was observed when leaves were infected with the pathogen Pseudomonas syringae pv. tomato, which persistently induces the JA signalling pathway. Yet, high resolution growth analyses of this effect in wild type and JA biosynthesis knock-out mutants showed that it was elicited by the bacterial toxin coronatine that suggests ethylene- but not JA-induced root growth reduction in A. thaliana. Overall, the results demonstrate that the reaction of root growth to herbivore-induced JA signalling differs among species, which is discussed in the context of different ecological defence strategies among species.

Topics: Acetates; Amino Acids; Animals; Arabidopsis; Cyclopentanes; Cyclopropanes; Ethylenes; Gene Knockout Techniques; Indenes; Oxylipins; Plant Leaves; Plant Roots; Pseudomonas syringae; Signal Transduction; Spodoptera

Ultraviolet B (UV-B) radiation, a very small fraction of the daylight spectrum, elicits changes in plant secondary metabolism that have large effects on plant-insect interactions. The signal transduction pathways that mediate these specific effects of solar UV-B are not known. We examined the role of jasmonate signaling by measuring responses to UV-B in wild-type and transgenic jasmonate-deficient Nicotiana attenuata plants in which a lipoxygenase gene (NaLOX3) was silenced (as-lox). In wild-type plants, UV-B failed to elicit the accumulation of jasmonic acid (JA) or the bioactive JA-isoleucine conjugate but amplified the response of jasmonate-inducible genes, such as trypsin proteinase inhibitor (TPI), to wounding and methyl jasmonate, and increased the accumulation of several phenylpropanoid derivatives. Some of these phenolic responses (accumulation of caffeoyl-polyamine conjugates) were completely lacking in as-lox plants, whereas others (accumulation of rutin and chlorogenic acid) were similar in both genotypes. In open field conditions, as-lox plants received more insect damage than wild-type plants, as expected, but the dramatic increase in resistance to herbivory elicited by UV-B exposure, which was highly significant in wild-type plants, did not occur in as-lox plants. We conclude that solar UV-B (1) uses jasmonate-dependent and -independent pathways in the elicitation of phenolic compounds, and (2) increases sensitivity to jasmonates, leading to enhanced expression of wound-response genes (TPI). The lack of UV-B-induced antiherbivore protection in as-lox plants suggests that jasmonate signaling plays a central role in the mechanisms by which solar UV-B increases resistance to insect herbivores in the field.

Topics: Acetates; Animals; Cyclopentanes; Gene Silencing; Insecta; Nicotiana; Oxylipins; Phenols; Plant Leaves; Plants, Genetically Modified; Signal Transduction; Sunlight; Ultraviolet Rays

Downy mildew is a destructive grapevine disease caused by Plasmopara viticola (Berk. and Curt.) Berl. and de Toni, which can only be controlled by intensive fungicide treatments. Natural sources of resistance from wild grapevine (Vitis) species are used in conventional breeding approaches, but the signals and effectors involved in resistance in this important crop species are not well understood.. Early transcriptional changes associated with P. viticola infection in susceptible V. vinifera and resistant V. riparia plants were analyzed using the Combimatrix microarray platform. Transcript levels were measured 12 and 24 h post-inoculation, reflecting the time points immediately preceding the onset of resistance in V. riparia, as determined by microscopic analysis. Our data indicate that resistance in V. riparia is induced after infection, and is not based on differences in basal gene expression between the two species. The strong and rapid transcriptional reprogramming involves the induction of pathogenesis-related proteins and enzymes required for the synthesis of phenylpropanoid-derived compounds, many of which are also induced, albeit to a lesser extent, in V. vinifera. More interestingly, resistance in V. riparia also involves the specific modulation of numerous transcripts encoding components of signal transduction cascades, hypersensitive reaction markers and genes involved in jasmonate biosynthesis. The limited transcriptional modulation in V. vinifera represents a weak attempted defense response rather than the activation of compatibility-specific pathways.. Several candidate resistance genes were identified that could be exploited in future biotechnological approaches to increase disease resistance in susceptible grapevine species. Measurements of jasmonic acid and methyl jasmonate in infected leaves suggest that this hormone may also be involved in V. riparia resistance to P. viticola.

Topics: Acetates; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Host-Pathogen Interactions; Immunity, Innate; Oligonucleotide Array Sequence Analysis; Oomycetes; Oxylipins; Plant Diseases; RNA, Plant; Signal Transduction; Species Specificity; Transcription, Genetic; Vitis

Mature seeds of yellow lupine contained sucrose, raffinose family oligosaccharides (RFOs), and galactosyl cyclitols as major soluble carbohydrates. The study showed that RFOs dominated in lupine seeds (16% DW). The disappearance of both types of alpha-d-galactosides in germinating lupine seeds was strongly inhibited by the presence of jasmonic acid-methyl ester (JA-Me) at a concentration of 10(-3)M in the incubation medium. JA-Me inhibited the activity of alpha-D-galactosidase (fraction I) during seed germination. Anatomical studies of lupine roots have shown certain cell structure differences between control and JA-Me-treated seedlings. The cross-sections of plant roots treated with JA-Me showed a characteristic folding of the cell walls in all root tissues, starting from the rhyzodermis, cortex and vascular cylinder. In water-treated (control) plants, the cell walls were rounded with no folding.

Topics: Acetates; Carbohydrates; Cyclopentanes; Galactosidases; Germination; Lupinus; Oxylipins; Plant Extracts; Plant Roots; Raffinose; Seeds

The plant hormone, jasmonic acid (JA), is known to have a critical role in both resistance and susceptibility against bacterial and fungal pathogen attack. However, little is known about the involvement of JA in the interactions between plants and toxigenic necrotrophic fungal pathogens. Using the tomato pathotype of Alternaria alternata (Aa) and its AAL-toxin/tomato interaction as a model system, we demonstrate a possible role for JA in susceptibility of plants against pathogens, which utilize host-specific toxins as virulence effectors. Disease development and in planta growth of the tomato pathotype of Aa were decreased in the def1 mutant, defective in biosynthesis of JA, compared with the wild-type (WT) cultivar. Exogenous methyl jasmonate (MeJA) application restored pathogen disease symptoms to the def1 mutant and led to increased disease in the WT. On the other hand, necrotic cell death was similarly induced by AAL-toxin both on def1 and WT, and MeJA application to the tomatoes did not affect the degree of cell death by the toxin. These results indicate that the JA-dependent signaling pathway is not involved in host basal defense responses against the tomato pathotype of Aa, but rather might affect pathogen acceptability via a toxin-independent manner. Data further suggest that JA has a promotional effect on susceptibility of tomato to toxigenic and necrotrophic pathogens, such that pathogens might utilize the JA signaling pathway for successful infection.

Topics: Acetates; Alternaria; Cyclopentanes; Fungal Proteins; Immunity, Innate; Mutation; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Leaves; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Solanum lycopersicum; Sphingosine

Herbivore feeding activates plant defenses at the site of damage as well as systemically. Systemic defenses can be induced internally by signals transported via phloem or xylem, or externally transmitted by volatiles emitted from the damaged tissues. We investigated the role of herbivore-induced plant volatiles (HIPVs) in activating a defense response between branches in blueberry plants. Blueberries are perennial shrubs that grow by initiating adventitious shoots from a basal crown, which produce new lateral branches. This type of growth constrains vascular connections between shoots and branches within plants. While we found that leaves within a branch were highly connected, vascular connectivity was limited between branches within shoots and absent between branches from different shoots. Larval feeding by gypsy moth, exogenous methyl jasmonate, and mechanical damage differentially induced volatile emissions in blueberry plants, and there was a positive correlation between amount of insect damage and volatile emission rates. Herbivore damage did not affect systemic defense induction when we isolated systemic branches from external exposure to HIPVs. Thus, internal signals were not capable of triggering systemic defenses among branches. However, exposure of branches to HIPVs from an adjacent branch decreased larval consumption by 70% compared to those exposed to volatiles from undamaged branches. This reduction in leaf consumption did not result in decreased volatile emissions, indicating that leaves became more responsive to herbivory (or "primed") after being exposed to HIPVs. Chemical profiles of leaves damaged by gypsy moth caterpillars, exposed to HIPVs, or non-damaged controls revealed that HIPV-exposed leaves had greater chemical similarities to damaged leaves than to control leaves. Insect-damaged leaves and young HIPV-exposed leaves had higher amounts of endogenous cis-jasmonic acid compared to undamaged and non-exposed leaves, respectively. Our results show that exposure to HIPVs triggered systemic induction of direct defenses against gypsy moth and primed volatile emissions, which can be an indirect defense. Blueberry plants appear to rely on HIPVs as external signals for inter-branch communication.

Topics: Acetates; Animals; Cyclopentanes; Gas Chromatography-Mass Spectrometry; Larva; Moths; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Physiological Phenomena; Signal Transduction; Vaccinium; Volatilization

Plant performance is affected by the level of expression of PsbS, a key photoprotective protein involved in the process of feedback de-excitation (FDE), or the qE component of non-photochemical quenching, NPQ.. In studies presented here, under constant laboratory conditions the metabolite profiles of leaves of wild-type Arabidopsis thaliana and plants lacking or overexpressing PsbS were very similar, but under natural conditions their differences in levels of PsbS expression were associated with major changes in metabolite profiles. Some carbohydrates and amino acids differed ten-fold in abundance between PsbS-lacking mutants and over-expressers, with wild-type plants having intermediate amounts, showing that a metabolic shift had occurred. The transcriptomes of the genotypes also varied under field conditions, and the genes induced in plants lacking PsbS were similar to those reportedly induced in plants exposed to ozone stress or treated with methyl jasmonate (MeJA). Genes involved in the biosynthesis of JA were up-regulated, and enzymes involved in this pathway accumulated. JA levels in the undamaged leaves of field-grown plants did not differ between wild-type and PsbS-lacking mutants, but they were higher in the mutants when they were exposed to herbivory.. These findings suggest that lack of FDE results in increased photooxidative stress in the chloroplasts of Arabidopsis plants grown in the field, which elicits a response at the transcriptome level, causing a redirection of metabolism from growth towards defence that resembles a MeJA/JA response.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Carbohydrate Metabolism; Chloroplasts; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Genotype; Light; Light-Harvesting Protein Complexes; Oligonucleotide Array Sequence Analysis; Oxylipins; Ozone; Photosynthesis; Photosynthetic Reaction Center Complex Proteins; Photosystem II Protein Complex; Stress, Physiological

The plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play crucial roles in the signaling network that regulates induced defense responses against biotic stresses. Antagonism between SA and JA operates as a mechanism to fine-tune defenses that are activated in response to multiple attackers. In Arabidopsis (Arabidopsis thaliana), NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (NPR1) was demonstrated to be required for SA-mediated suppression of JA-dependent defenses. Because ET is known to enhance SA/NPR1-dependent defense responses, we investigated the role of ET in the SA-JA signal interaction. Pharmacological experiments with gaseous ET and the ET precursor 1-aminocyclopropane-1-carboxylic acid showed that ET potentiated SA/NPR1-dependent PATHOGENESIS-RELATED1 transcription, while it rendered the antagonistic effect of SA on methyl jasmonate-induced PDF1.2 and VSP2 expression NPR1 independent. This overriding effect of ET on NPR1 function in SA-JA cross talk was absent in the npr1-1/ein2-1 double mutant, demonstrating that it is mediated via ET signaling. Abiotic and biotic induction of the ET response similarly abolished the NPR1 dependency of the SA-JA signal interaction. Furthermore, JA-dependent resistance against biotic attackers was antagonized by SA in an NPR1-dependent fashion only when the plant-attacker combination did not result in the production of high levels of endogenous ET. Hence, the interaction between ET and NPR1 plays an important modulating role in the fine tuning of the defense signaling network that is activated upon pathogen and insect attack. Our results suggest a model in which ET modulates the NPR1 dependency of SA-JA antagonism, possibly to compensate for enhanced allocation of NPR1 to function in SA-dependent activation of PR genes.

Topics: Acetates; Amino Acids, Cyclic; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Immunity, Innate; Models, Biological; Oxylipins; Plant Diseases; Receptors, Cell Surface; Salicylic Acid; Signal Transduction

The plant photoreceptor phytochrome is organised in a small gene family with phytochrome A (phyA) being unique, because it is specifically degraded upon activation by light. This so called photodestruction is thought to be important for dynamic aspects of sensing such as measuring day length or shading by competitors. Signal-triggered proteolytic degradation has emerged as central element of signal crosstalk in plants during recent years, but many of the molecular players are still unknown. We therefore analyzed a jasmonate (JA)-deficient rice mutant, hebiba, that in several aspects resembles a mutant affected in photomorphogenesis. In this mutant, the photodestruction of phyA is delayed as shown by in vivo spectroscopy and Western blot analysis. Application of methyl-JA (MeJA) can rescue the delayed phyA photodestruction in the mutant in a time- and dose-dependent manner. Light regulation of phyA transcripts thought to be under control of stable phytochrome B (phyB) is still functional. The delayed photodestruction is accompanied by an elevated sensitivity of phytochrome-dependent growth responses to red and far-red light.

Topics: Acetates; Blotting, Western; Cotyledon; Cyclopentanes; Gene Expression Regulation, Plant; Indoleacetic Acids; Light; Mutation; Oryza; Oxylipins; Phytochrome A; Protein Processing, Post-Translational; RNA, Messenger; Seedlings; Time Factors

Members of the aldo-keto reductase (AKR) superfamily, particularly the AKR1C subfamily, are emerging as important mediators of the pathology of cancer. Agents that inhibit these enzymes may provide novel agents for either the chemoprevention or treatment of diverse malignancies. Recently, jasmonates, a family of plant stress hormones that bear a structural resemblance to prostaglandins, have been shown to elicit anticancer activities both in vitro and in vivo. In this study, we show that jasmonic acid (JA) and methyl jasmonate (MeJ) are capable of inhibiting all four human AKR1C isoforms. Although JA is the more potent inhibitor of recombinant AKR1C proteins, including the in vitro prostaglandin F synthase activity of AKR1C3, MeJ displayed greater potency in cellular systems that was, at least in part, due to increased cellular uptake of MeJ. Moreover, using the acute myelogenous leukemia cell lines HL-60 and KG1a, we found that although both jasmonates were able to induce high levels of reactive oxygen species in a dose-dependent fashion, only MeJ was able to induce high levels of mitochondrial superoxide (MSO), possibly as an epiphenomenon of mitochondrial damage. There was a strong correlation observed between MSO formation at 24 hours and reduced cellularity at day 5. In conclusion, we have identified AKR1C isoforms as a novel target of jasmonates in cancer cells and provide further evidence of the promise of these compounds, or derivatives thereof, as adjunctive therapies in the treatment of cancer.

Topics: 20-Hydroxysteroid Dehydrogenases; Acetates; Cell Survival; Cells, Cultured; Cyclopentanes; Drug Delivery Systems; Drug Evaluation, Preclinical; Enzyme Inhibitors; HL-60 Cells; Humans; Hydroxyprostaglandin Dehydrogenases; Isoenzymes; Leukemia, Myeloid; Mitochondria; Models, Biological; Oxylipins; Prostaglandin D2; Reactive Oxygen Species

Herbivore- and jasmonate-induced volatile organic compounds (VOCs), which mediate indirect defense, must provide reliable information for predators that frequently learn to associate their release with feeding herbivores. Yet little is known about variation of these cues within populations of native plants, on a scale encountered by predators. We examined variation in herbivore-elicited VOC emissions and patterns of herbivore-induced jasmonate signaling from accessions of Nicotiana attenuata co-occurring in a native population. VOC emissions elicited by herbivore oral secretions (OS) and by methyl jasmonate (MJ) were characterized using gas chromatography-mass spectrometry (GC-MS), high-resolution two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-ToF-MS) and micro-hydrolysis and micro-hydrogenation reactions. Accessions varied in emissions of abundant (trans-alpha-bergamotene, alpha-duprezianene, trans-beta-ocimene, and cis-3-hexenol) and total detectable VOCs, as well as the accumulation of jasmonates, the jasmonate antagonist salicylic acid (SA), abscisic acid (ABA) and jasmonate signaling-related transcripts after OS elicitation. Yet MJ treatment exacerbated differences in VOC emission, suggesting that much variation in VOC emission is caused by processes downstream of jasmonate signaling. Co-occurring N. attenuata plants emit different VOCs following simulated herbivore elicitation as a result in part of differences in jasmonate production and responsiveness, which could reduce the effectiveness of induced indirect defense.

Topics: Abscisic Acid; Acetates; Animals; Cyclopentanes; Gas Chromatography-Mass Spectrometry; Nicotiana; Oils, Volatile; Oxylipins; Plant Growth Regulators; Polymorphism, Genetic; Salicylic Acid; Signal Transduction

Abscisic acid (ABA) and Jasmonic acid (JA) play an important role in inducing the stress-resistance of plants. In this study, parts of the needles on a ring of Pinus massoniana seedling shoots were subjected to 4 hours Dendrolimus punctatus feeding or 4 hours fumigation with 10 micromol x L(-1) of methyl jasmonate (MeJA) or terpenes, and the ABA and JA contents in treated needles, untreated neighboring sister needles, and untreated needles above and below the ring were determined by GC/MS. An obvious increase of ABA and JA contents was observed in all of the needles, whether they were treated or not, illustrating that ABA and JA were the vital signaling molecules in the wound signal transduction pathway, and participated in the formation of systematic resistance of P. massoniana seedlings.

Topics: Abscisic Acid; Acetates; Animals; Cyclopentanes; Moths; Oxylipins; Pinus; Plant Growth Regulators; Plant Leaves; Seedlings; Terpenes

Adventitious roots (ARs) are induced by auxins. Jasmonic acid (JA) and methyl jasmonate (MeJA) are also plant growth regulators with many effects on development, but their role on ARs needs investigation. To this aim, we analyzed AR formation in tobacco thin cell layers (TCLs) cultured with 0.01-10 microM MeJA, either under root-inductive conditions, i.e., on medium containing 10 microM indole-3-butyric acid (IBA) and 0.1 microM kinetin, or without hormones. The explants were excised from the cultivars Samsun, Xanthii and Petite Havana, and from genotypes with altered AR-forming ability in response to auxin, namely the non-rooting rac mutant and the over-rooting Agrobacterium rhizogenes rolB transgenic line. Results show that NtRNR1 (G1/S) and Ntcyc29 (G2/M) gene activity, cell proliferation and meristemoid formation were stimulated in hormone-cultured TCLs by submicromolar MeJA concentrations. The meristemoids developed either into ARs and xylogenic nodules, or into xylogenic nodules only (rac TCLs). MeJA-induced meristemoid over-production characterized rolB TCLs. No rooting or xylogenesis occurred under hormone-free conditions, independently of MeJA and genotype. Endogenous JA progressively (days 1-4) increased in hormone-cultured TCLs in the absence of MeJA. JA levels were enhanced by 0.1 microM MeJA, on both days 1 and 4. Endogenous IBA was the only auxin detected, both in the free form and as IBA-glucose. Free IBA increased up to day 2, remaining constant thereafter (day 4). Its level was enhanced by 0.1 microM MeJA only on day 1, while IBA conjugation was not affected by MeJA. Taken together, these results show that an interplay between jasmonates and auxins regulates AR formation and xylogenesis in tobacco TCLs.

Topics: Acetates; Cells, Cultured; Cyclopentanes; Gene Expression Regulation, Plant; Indoles; Interphase; Meristem; Mitosis; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Proteins; Plant Roots; Xylem

In plants, ethylene and jasmonate control the defense responses to multiple stressors, including insect predation. Among the defense proteins known to be regulated by ethylene is maize insect resistance 1-cysteine protease (Mir1-CP). This protein is constitutively expressed in the insect-resistant maize (Zea mays) genotype Mp708; however, its abundance significantly increases during fall armyworm (Spodoptera frugiperda) herbivory. Within 1 h of herbivory by fall armyworm, Mir1-CP accumulates at the feeding site and continues to increase in abundance until 24 h without any increase in its transcript (mir1) levels. To resolve this discrepancy and elucidate the role of ethylene and jasmonate in the signaling of Mir1-CP expression, the effects of phytohormone biosynthesis and perception inhibitors on Mir1-CP expression were tested. Immunoblot analysis of Mir1-CP accumulation and quantitative reverse-transcriptase polymerase chain reaction examination of mir1 levels in these treated plants demonstrate that Mir1-CP accumulation is regulated by both transcript abundance and protein expression levels. The results also suggest that jasmonate functions upstream of ethylene in the Mir1-CP expression pathway, allowing for both low-level constitutive expression and a two-stage defensive response, an immediate response involving Mir1-CP accumulation and a delayed response inducing mir1 transcript expression.

Topics: Acetates; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Oxylipins; Plant Growth Regulators; Plant Proteins; Signal Transduction; Zea mays

Cross talk between salicylic acid (SA) and jasmonic acid (JA) signaling pathways plays an important role in the regulation and fine tuning of induced defenses that are activated upon pathogen or insect attack. Pharmacological experiments revealed that transcription of JA-responsive marker genes, such as PDF1.2 and VSP2, is highly sensitive to suppression by SA. This antagonistic effect of SA on JA signaling was also observed when the JA pathway was biologically activated by necrotrophic pathogens or insect herbivores, and when the SA pathway was triggered by a biotrophic pathogen. Furthermore, all 18 Arabidopsis (Arabidopsis thaliana) accessions tested displayed SA-mediated suppression of JA-responsive gene expression, highlighting the potential significance of this phenomenon in induced plant defenses in nature. During plant-attacker interactions, the kinetics of SA and JA signaling are highly dynamic. Mimicking this dynamic response by applying SA and methyl jasmonate (MeJA) at different concentrations and time intervals revealed that PDF1.2 transcription is readily suppressed when the SA response was activated at or after the onset of the JA response, and that this SA-JA antagonism is long lasting. However, when SA was applied more than 30 h prior to the onset of the JA response, the suppressive effect of SA was completely absent. The window of opportunity of SA to suppress MeJA-induced PDF1.2 transcription coincided with a transient increase in glutathione levels. The glutathione biosynthesis inhibitor l-buthionine-sulfoximine strongly reduced PDF1.2 suppression by SA, suggesting that SA-mediated redox modulation plays an important role in the SA-mediated attenuation of the JA signaling pathway.

Topics: Acetates; Adaptation, Physiological; Animals; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Defensins; Gene Expression Regulation, Plant; Glutathione; Host-Parasite Interactions; Insecta; Kinetics; Oxidation-Reduction; Oxylipins; Receptor Cross-Talk; Salicylic Acid; Signal Transduction

Methyl jasmonate (MeJA) was identified as an airborne signal involved in mediating interplant defense response communications over a decade ago. However, how MeJA activates plant defense systems and what becomes of the compound after it has done so has, thus far, remained unknown. To investigate this, Achyranthes bidentata plants were exposed to deuterated methyl jasmonate (d(2)MeJA) followed by absolute quantification of metabolic products of d(2)MeJA, and emissions of volatile organic compound (VOC) as defensive markers. We found that d(2)MeJA was metabolized mainly into deuterated jasmonic acid (d(2)JA) and jasmonoyl isoleucine (d(2)JA-Ile), and to a much lesser extent, deuterated jasmonoyl leucine (d(2)JA-Leu). Increases in d(2)JA-Ile/Leu and also endogenous JA-Ile/Leu were tightly co-related with, and significantly influenced the pattern and amount of, VOC emissions. The amount of accumulated d(2)JA-IIe was 13.1-fold higher than d(2)JA-Leu, whereas the amounts of JA-IIe and JA-Leu accumulated were almost identical. This study demonstrates that exogenous MeJA activates defensive systems (such as VOC emissions) in receiver plants by essentially converting itself into JA and JA-IIe and initiating a signal transduction leading to VOC emissions and induction of endogenous JA-IIe and JA-Leu, which in turn cause further amplification of VOC emissions.

Topics: Acetates; Achyranthes; Cyclopentanes; Isoleucine; Oxylipins; Signal Transduction; Volatilization

Induced chemical defense reactions are widespread in marine brown algae. Despite the evidence that the biosynthesis of defense metabolites can be up-regulated upon herbivory, we do not know how this regulation of biosynthetic pathways to secondary metabolites is achieved in brown algae. In higher plants, the phytohormone jasmonic acid (JA) is crucial for the mediation of induced chemical defenses, and several findings of this metabolite from marine sources have been reported. We tested the hypothesis that JA or related metabolites play a role in induced brown algal defense. Quantification of oxylipins with a detection limit around 20 ng g(-1) algal tissue did not reveal the presence of JA in the seven examined brown algal species Dictyota dichotoma, Colpomenia peregrina, Ectocarpus fasciculatus, Fucus vesiculosus, Himanthalia elongata, Saccharina latissima (formerly Laminaria saccharina), and Sargassum muticum. Moreover, treatment with ecologically relevant concentrations of JA and methyl jasmonate did not lead to a significant change in the profile of medium- and non-polar metabolites of the tested algae. Only when high concentrations of > or =500 microg ml(-1) medium of the phytohormones were applied that a metabolic response which could be attributed to unspecific stress was observed. Bioassays with D. dichotoma that focused on medium- and non-polar compounds confirmed the lack of a biological role of JA and methyl jasmonate in the induction of algal induced chemical defenses. The phytohormone-treated samples did not exhibit any increased defense potential towards the amphipod Ampithoe longimana and the isopod Paracerceis caudata. JA and related phytohormones, known to be active in higher plants, thus appear to play no role in brown algae for induction of the defense chemicals studied here.

Topics: Acetates; Artifacts; Biological Assay; Biomimetic Materials; Cyclopentanes; Oxylipins; Phaeophyceae; Plant Growth Regulators; Terpenes

Whereas jasmonic acid (JA) and its amino acid conjugates, particularly JA-isoleucine (Ile), are known to play important roles in plant-herbivore interactions, whether other compounds also function as signals independently of JA-Ile and whether conjugates elicit systemic responses are unknown. To answer these questions, we simultaneously silenced JASMONATE-RESISTANT4 (JAR4) and JAR6, two functionally redundant enzymes in Nicotiana attenuata that conjugate JA to amino acids to produce plants (irjar4/6) with low levels of JA-Ile, JA-leucine (Leu), and JA-valine (Val; <16% of wild type). As expected, irjar4/6 plants are more vulnerable to herbivore attack, but only JA-Ile -- not JA-Leu or JA-Val -- applications restored the resistance of irjar4/6 plants, suggesting that JA-Leu and JA-Val do not mediate herbivore defense responses. Interestingly, the direct defense traits of irjar4/6 plants are significantly higher than those in LIPOXYGENASE3 (LOX3)-silenced (aslox3) plants, which are impaired in JA biosynthesis, and JA-Ile treatment could not fully restore the resistance of aslox3 plants. We thus conclude that JA, its precursors, or other metabolites complement the function of JA-Ile by eliciting a panoply of induced defenses. Similarly, transcriptional profiling of wild-type, irjar4/6, and aslox3 plants with microarrays demonstrated that JA-Ile and JA play overlapping yet distinct roles in herbivore defense. Analysis of transcripts in distal tissues demonstrated that JAR activity is essential in eliciting systemic responses. However, attempts to recover JA-(13)C(6)-Ile in systemic leaves and roots after feeding wounded leaves with (13)C(6)-Ile were unsuccessful, suggesting that JA-Ile is not a long-distance signal, but is rather synthesized after the arrival of an unknown mobile signal to systemic tissues.

Topics: Acetates; Adaptation, Physiological; Amino Acids; Animals; Cyclopentanes; Gene Expression Profiling; Gene Silencing; Host-Parasite Interactions; Larva; Lipoxygenase; Manduca; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Proteins; Signal Transduction

Jasmonates (JAs) are plant-specific signaling molecules that steer a diverse set of physiological and developmental processes. Pathogen attack and wounding inflicted by herbivores induce the biosynthesis of these hormones, triggering defense responses both locally and systemically. We report on alterations in the transcriptome of a fast-dividing cell culture of the model plant Arabidopsis thaliana after exogenous application of methyl JA (MeJA). Early MeJA response genes encoded the JA biosynthesis pathway proteins and key regulators of MeJA responses, including most JA ZIM domain proteins and MYC2, together with transcriptional regulators with potential, but yet unknown, functions in MeJA signaling. In a second transcriptional wave, MeJA reprogrammed cellular metabolism and cell cycle progression. Up-regulation of the monolignol biosynthesis gene set resulted in an increased production of monolignols and oligolignols, the building blocks of lignin. Simultaneously, MeJA repressed activation of M-phase genes, arresting the cell cycle in G(2). MeJA-responsive transcription factors were screened for their involvement in early signaling events, in particular the regulation of JA biosynthesis. Parallel screens based on yeast one-hybrid and transient transactivation assays identified both positive (MYC2 and the AP2/ERF factor ORA47) and negative (the C2H2 Zn finger proteins STZ/ZAT10 and AZF2) regulators, revealing a complex control of the JA autoregulatory loop and possibly other MeJA-mediated downstream processes.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cell Cycle; Cells, Cultured; Cyclopentanes; Gene Expression Profiling; Gene Expression Regulation, Plant; Growth Inhibitors; Oxylipins; Plant Growth Regulators; Signal Transduction; Transcription Factors; Transcription, Genetic

Peach (Prunus persica L. Batsch) was chosen as a model to shed light on the physiological role of jasmonates (JAs) during fruit ripening. To this aim, the effects of methyl jasmonate (MJ, 0.40 mM) and propyl dihydrojasmonate (PDJ, 0.22 mM), applied in planta at different fruit developmental stages, on the time-course of ethylene production and fruit quality traits were evaluated. MJ-induced changes in fruit transcriptome at harvest and the expression profiling of relevant JA-responsive genes were analysed in control and JA-treated fruit. Exogenously applied JAs affected the onset of ripening depending upon the fruit developmental stage, with PDJ being more active than MJ. Both compounds enhanced the transcription of allene oxide synthase (PpAOS1), the first specific enzyme in the biosynthesis of jasmonic acid, and altered the pattern of jasmonic acid accumulation. Microarray transcriptome profiling showed that MJ down-regulated some ripening-related genes, such as 1-aminocyclopropane-1-carboxylic acid oxidase (PpACO1) and polygalacturonase (PG), and the transcriptional modulator IAA7. MJ also altered the expression of cell wall-related genes, namely pectate lyase (PL) and expansins (EXPs), and up-regulated several stress-related genes, including some of those involved in JA biosynthesis. Time-course expression profiles of PpACO1, PL, PG, PpExp1, and the transcription factor LIM confirmed the array results. Thus, in peach fruit, exogenous JAs led to a ripening delay due to an interference with ripening- and stress/defence-related genes, as reflected in the transcriptome of treated fruit at harvest.

Topics: Acetates; Cyclopentanes; Ethylenes; Fruit; Gene Expression Profiling; Gene Expression Regulation, Plant; Intramolecular Oxidoreductases; Oxylipins; Prunus; Time Factors

Biosynthesis of many plant alkaloids is enhanced by endogenous accumulation and exogenous application of jasmonates, but the general and specific signaling components are not well understood. In Arabidopsis, jasmonate-induced ZIM-domain-containing (JAZ) proteins have recently been found to be critical transcriptional repressors linking CORONATINE INSENSTIVE1 (COI1)-mediated jasmonate perception and jasmonate-regulated transcriptional regulation. Insect herbivory on tobacco leaves activates the jasmonate signaling pathway, leading to up-regulation of nicotine biosynthesis genes in roots. We show here that roots of COI1-silenced tobacco plants are insensitive to growth inhibition by methyl jasmonate, and do not activate nicotine biosynthesis genes after jasmonate treatment or wounding of leaves. Tobacco JAZ proteins appeared to be rapidly degraded after jasmonate treatment, whereas a C-terminally truncated form lacking the conserved Jas motif did not. When the non-degradable JAZ forms were expressed in tobacco hairy roots, jasmonate induction of nicotine biosynthesis was strongly inhibited. Formation of tobacco alkaloids in jasmonate-elicited tobacco BY-2 cells was also effectively suppressed by the COI1 RNAi (RNA interference) construct and by the dominant-negative truncated JAZ constructs. In addition, jasmonate-mediated induction of nicotine biosynthesis genes was diminished by treatment with a proteasome inhibitor MG132. These results indicate that jasmonate-triggered, COI1-mediated degradation of JAZ repressors activates transcriptional regulation of nicotine biosynthesis genes in tobacco roots.

Topics: Acetates; Cyclopentanes; Gene Expression Regulation, Plant; Genes, Dominant; Genes, Plant; Leupeptins; Molecular Sequence Data; Nicotiana; Nicotine; Oxylipins; Plant Proteins; Plant Roots; Proteasome Inhibitors; Protein Processing, Post-Translational; RNA Interference; Suppression, Genetic

To elucidate the role of acyl-CoA oxidase (ACX; EC 1.3.3.6) in plants, the expression patterns of rice ACXs in response to wounding were characterized. Three isogenes of ACX were identified in the rice genome. The deduced proteins of OsACX1, OsACX2 and OsACX3 consist of 669, 699 and 685 amino acid residues, respectively. The results from reverse transcriptase-PCR indicate that OsACX1 is expressed in leaves, stems, and roots, but was barely detectable in germinating seeds. OsACX2 was expressed predominantly in seeds. Only OsACX1 was upregulated by wounding, both locally and systemically. The expression of OsACX2 and OsACX3 remained unchanged. It is suggested that OsACX2 is involved in providing germinating seeds with sugar and energy, while OsACX1 plays a role in the synthesis of jasmonic acid in response to wounding.

Topics: Acetates; Acyl-CoA Oxidase; Cyclopentanes; Enzyme Induction; Gene Expression Regulation, Plant; Isoenzymes; Oryza; Oxylipins; Plant Diseases; Plant Leaves

* Accumulation of methyl jasmonate (MeJA) after herbivore attack in plants is associated with the induction of defenses that can benefit fitness, but are costly to express; effects often explored using exogenous application of jasmonates. * Here I explored the consequences of the overexpression of MeJA on seed production, tolerance to defoliation and competitive effect and response, using a genotype of Arabidopsis thaliana that overexpresses jasmonic acid carboxyl methyltransferase (JMT) and contains threefold higher levels of MeJA than wild-type plants. * Without competition, JMT plants produced 37-40% less total seed mass than vector controls or wild-type plants, and had reduced seed germination. Defoliation reduced height more strongly in wild-type than in JMT plants, but reduced total seed production equally. In a competition experiment, the presence of a neighbor reduced fitness more strongly in wild-type than in JMT plants, but JMT plants exhibited dampened opportunity costs and benefits of induction with jasmonic acid of itself or its neighbor. This may have related to the higher constitutive expression but reduced inducibility of jasmonate-mediated defenses, including trypsin inhibitors, exhibited by JMT plants. * In natural plant populations, overexpression of MeJA-mediated responses should be beneficial to resistance to herbivores, pathogens and competitors, but is directly costly to fitness and probably constrains plasticity in response to changing environmental conditions.

Topics: Acetates; Arabidopsis; Cyclopentanes; Genotype; Methyltransferases; Oxylipins; Plant Leaves; Seeds; Trypsin Inhibitors

Phloem cells adjacent to sieve elements can possess wall invaginations. The role of light and jasmonic acid signaling in wall ingrowth development was examined in pea companion cells (CCs), Arabidopsis thaliana phloem parenchyma cells (PCs), and in Senecio vulgaris (with ingrowths in both cell types). Features characterized included wall ingrowths (from electron microscopic images), foliar vein density and photosynthetic capacity. In Arabidopsis, wall ingrowths were bulky compared with finger-like invaginations in pea and S. vulgaris. Relative to low light (LL), wall invagination in both CCs and PCs was greater in high light (HL). Treatment with methyl jasmonate in LL had no effect on CCs, but increased PC wall ingrowths. LL-to-HL transfer resulted in significantly less wall ingrowth in the fad7-1 fad8-1 (jasmonate-deficient) Arabidopsis mutant relative to the wild type. These results suggest that chloroplast oxidative status, via chloroplast-derived jasmonates, may modulate phloem structure and function. While CC wall ingrowths facilitate phloem loading by expanding the membrane area available for active uptake, one can speculate that phloem PC ingrowths may have two potential roles: to increase the efflux of sugars and/or protons into the apoplast to augment phloem loading; and/or to protect the phloem against pathogens and/or insects.

Topics: Acetates; Arabidopsis; Cell Wall; Cyclopentanes; Light; Mutation; Oxylipins; Phloem; Photosynthesis; Pisum sativum; Plant Leaves; Senecio; Signal Transduction

No current treatment reliably affects the course of metastatic melanoma. Consequently, novel approaches to the control of metastasis are actively sought. The overall goal of the present study was to identify new anti-metastatic agents active against melanoma cells.. Two directions were taken: 1. To determine whether the natural plant hormone methyl jasmonate, which kills cancer cells selectively, can suppress the characteristic metastatic behavior of B16-F10 melanoma cells; 2. To synthesize and identify novel jasmonate derivatives with better cytotoxic and anti-metastatic activities than methyl jasmonate.. We found that methyl jasmonate suppressed B16-F10 cell motility and inhibited the development of experimental lung metastases of these cells. Furthermore, methyl jasmonate suppressed the motility of a sub-clone of these cells over-expressing P-glycoprotein and exhibiting multidrug resistance. The synthetic derivative Compound I (5,7,9,10-tetrabromo derivative of methyl jasmonate, the most active derivative) had greater cytotoxic potency (IC(50), 0.04 mM) than methyl jasmonate (IC(50), 2.6mM). Compound I prevented B16-F10 cell adhesion efficiently and inhibited the development of lung metastases at a much lower dose than methyl jasmonate.. Natural and synthetic jasmonates have anti-metastatic actions. Further development of these agents for the suppression of metastasis in melanoma and other types of cancer is warranted.

Topics: Acetates; Animals; Antineoplastic Agents, Phytogenic; Cell Line, Tumor; Cyclopentanes; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Lung Neoplasms; Male; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Oxylipins

The long-distance transport and actions of the phytohormone methyl jasmonate (MeJA) were investigated by using the short-lived positron-emitting isotope 11C to label both MeJA and photoassimilate, and compare their transport properties in the same tobacco plants (Nicotiana tabacum L.). There was strong evidence that MeJA moves in both phloem and xylem pathways, because MeJA was exported from the labeled region of a mature leaf in the direction of phloem flow, but it also moved into other parts of the same leaf and other mature leaves against the direction of phloem flow. This suggests that MeJA enters the phloem and moves in sieve tube sap along with photoassimilate, but that vigorous exchange between phloem and xylem allows movement in xylem to regions which are sources of photoassimilate. This exchange may be enhanced by the volatility of MeJA, which moved readily between non-orthostichous vascular pathways, unlike reports for jasmonic acid (which is not volatile). The phloem loading of MeJA was found to be inhibited by parachloromercuribenzenesulfonic acid (PCMBS) (a thiol reagent known to inhibit membrane transporters), and by protonophores carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP) suggesting proton co-transport. MeJA was found to promote both its own transport and that of recent photoassimilate within 60 min. Furthermore, we found that MeJA can counter the inhibitory effect of the uncoupling agent, CCCP, on sugar transport, suggesting that MeJA affects the plasma membrane proton gradient. We also found that MeJA's action may extend to the sucrose transporter, since MeJA countered the inhibitory effects of the sulfhydryl reagent, PCMBS, on the transport of photoassimilate.

Topics: 2,4-Dinitrophenol; 4-Chloromercuribenzenesulfonate; Acetates; Biological Transport; Carbon Radioisotopes; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Cyclopentanes; Nicotiana; Oxylipins; Phloem; Photosynthesis; Xylem

Rice microarray analysis showed that a number of stress-related genes are induced by external addition of L-ascorbic acid (AsA). The gene designated as AK073843 which is homologous to class capital SHA, Cyrillic chitinase was found to exhibit the highest induction among these genes. However, its crucial residues within the chitinase active site are substituted with other residues, suggesting that the protein has no chitinase activity. The recombinant protein which is encoded by the AK073843 gene produced in Escherichia coli has xylanase inhibitor activity, indicating that the gene encodes a novel rice XIP-type xylanase inhibitor protein (OsXIP). The expression of OsXIP was enhanced not only by exogenous AsA treatment but also by various stresses such as citrate and sodium chloride treatments, and wounding; however, it was not influenced by increasing endogenous AsA content. External AsA treatment caused a significant increase in electrolyte leakage from rice root. These results suggested that OsXIP was induced by stress which is caused by external AsA treatment. Rice XIP-family genes, OsXIP, riceXIP and RIXI, showed differential organ-specific expression. Also, these genes were differentially induced by stress and stress-related phytohormones. The transcripts of OsXIP and riceXIP were undetectable under normal conditions, and were drastically induced by wounding and methyl jasmonate (MeJA) treatment in the root. RIXI was constitutively expressed in the shoot but not induced by wounding and stress-related phytohormones. Thus, XIP-type xylanase inhibitors were suggested to be specialized in their function and involved in defense mechanisms in rice.

Topics: Acetates; Amino Acid Sequence; Ascorbic Acid; Blotting, Northern; Cyclopentanes; Gene Expression Regulation, Plant; Molecular Sequence Data; Oligonucleotide Array Sequence Analysis; Oryza; Oxylipins; Phylogeny; Plant Proteins; Salicylic Acid; Seedlings; Seeds; Sequence Alignment; Sequence Analysis, DNA; Xylosidases

Signaling cascades involving oxygenated derivatives (oxylipins) of polyunsaturated fatty acids (PUFAs) are known to operate in response to external stimuli. The marine red alga Chondrus crispus uses both oxygenated derivatives of C18 (octadecanoids) and C20 (eicosanoids) PUFAs as developmental or defense hormones. The present study demonstrates that methyljasmonate (MeJA) triggers a cascade of oxidation of PUFAs leading to the synthesis of prostaglandins and other oxygenated fatty acids. As a result of a lipoxygenase-like activation, MeJA induces a concomitant accumulation of 13-hydroxy-9Z,11E-octadecadienoic acid (13-HODE) and 13-oxo-9Z,11E-octadecadienoic acid (13-oxo-ODE) in a dose-dependent manner in C. crispus. Furthermore, MeJA increases the level of mRNA encoding a gluthatione S-transferase and induces the activity of a new enzyme catalyzing the regio- and stereoselective bisallylic hydroxylation of polyunsaturated fatty acids from C(18) to C(22). The enzyme selectively oxidized the omega minus 7 carbon position (omega-7) and generated the stereoselective (R)-hydroxylated metabolites with a large enantiomeric excess. The enzyme specificity for the fatty acid recognition was not dependent of the position of double bonds but at least requires a methylene interrupted double bond 1,4-pentadiene motif involving the omega-7 carbon.

Topics: Acetates; Algal Proteins; Chondrus; Cyclopentanes; Dinoprostone; DNA Primers; Fatty Acids, Unsaturated; Gas Chromatography-Mass Spectrometry; Kinetics; Linoleic Acid; Mixed Function Oxygenases; Oxylipins; Polymerase Chain Reaction; Prostaglandins A; RNA; Substrate Specificity

Methyl jasmonate (MeJA) is a plant-signaling molecule that regulates plant morphogenesis and expression of plant defense genes. To determine the role of the endogenous MeJA levels in the development of plants, transgenic soybean [Glycine max (L.) Merrill] plants harboring NTR1 gene encoding for jasmonic acid carboxyl methyltransferase (JMT) were produced. The activation of NTR1 gene expression resulted in the production of MeJA. Overexpression of the NTR1 cDNA under the regulation of cauliflower mosaic virus (CaMV) 35S promoter in the transgenic soybean plants was confirmed using Northern blot analysis. The significant differences in leaf and root growth patterns were observed between the transgenic plants and the wild-type plants. The leaves of the transgenic plants were slightly elongated in length but dramatically narrowed in width compared with the nontransformed wild-type plants. In addition, elongation of primary root was inhibited in the overexpressed transgenic soybean plantlets, whereas the development of lateral root was stimulated relative to the nontransformed plants. The leaves of the transgenic plants showed 2-2.5-fold higher levels of MeJA than the control plants. These results indicated that the increased endogenous levels of MeJA is involved in regulation of morphogenesis in soybean plants.

Topics: Acetates; Caulimovirus; Cyclopentanes; Gene Expression; Glycine max; Morphogenesis; Oxylipins; Phenotype; Plant Leaves; Plant Roots; Plants, Genetically Modified; Polymerase Chain Reaction; Promoter Regions, Genetic; Receptors, Neurotensin

Previous experiments with tobacco (Nicotiana tabacum L. cv Samsun NN) plants revealed that jasmonic acid methyl ester (JAME) induces the expression of a cytoplasmic/nuclear lectin in leaf cells and provided the first evidence that jasmonates affect the expression of carbohydrate-binding proteins in plant cells. To corroborate the induced accumulation of relatively large amounts of a cytoplasmic/nuclear lectin, a detailed study was performed on the induction of the lectin in both intact tobacco plants and excised leaves. Experiments with different stress factors demonstrated that the lectin is exclusively induced by exogeneously applied jasmonic acid and JAME, and to a lesser extent by insect herbivory. The lectin concentration depends on leaf age and the position of the tissue in the leaf. JAME acts systemically in intact plants but very locally in excised leaves. Kinetic analyses indicated that the lectin is synthesized within 12 h exposure time to JAME, reaching a maximum after 60 h. After removal of JAME, the lectin progressively disappears from the leaf tissue. The JAME-induced accumulation of an abundant nuclear/cytoplasmic lectin is discussed in view of the possible role of this lectin in the plant.

Topics: Acetates; Animals; Cyclopentanes; Gene Expression Regulation, Plant; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Lectins; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Spodoptera; Time Factors

Conifers produce terpenoid-based oleoresins as constitutive and inducible defenses against herbivores and pathogens. Much information is available about the genes and enzymes of the late steps of oleoresin terpenoid biosynthesis in conifers, but almost nothing is known about the early steps which proceed via the methylerythritol phosphate (MEP) pathway. Here we report the cDNA cloning and functional identification of three Norway spruce (Picea abies) genes encoding 1-deoxy-D-xylulose 5-phosphate synthase (DXS), which catalyzes the first step of the MEP pathway, and their differential expression in the stems of young saplings. Among them are representatives of both types of plant DXS genes. A single type I DXS gene is constitutively expressed in bark tissue and not affected by wounding or fungal application. In contrast, two distinct type II DXS genes, PaDXS2A and PaDXS2B, showed increased transcript abundance after these treatments as did two other genes of the MEP pathway tested, 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) and 4-hydroxyl 3-methylbutenyl diphosphate reductase (HDR). We also measured gene expression in a Norway spruce cell suspension culture system that, like intact trees, accumulates monoterpenes after treatment with methyl jasmonate. These cell cultures were characterized by an up-regulation of monoterpene synthase gene transcripts and enzyme activity after elicitor treatment, as well as induced formation of octadecanoids, including jasmonic acid and 12-oxophytodienoic acid. Among the Type II DXS genes in cell cultures, PaDXS2A was induced by treatment with chitosan, methyl salicylate, and Ceratocystis polonica (a bark beetle-associated, blue-staining fungal pathogen of Norway spruce). However, PaDXS2B was induced by treatment with methyl jasmonate and chitosan, but was not affected by methyl salicylate or C. polonica. Our results suggest distinct functions of the three DXS genes in primary and defensive terpenoid metabolism in Norway spruce.

Topics: Acetates; Amino Acid Sequence; Cells, Cultured; Cloning, Molecular; Cyclopentanes; Fatty Acids, Unsaturated; Gene Expression Regulation, Plant; Gene Library; Intramolecular Lyases; Molecular Sequence Data; Oxylipins; Picea; Resins, Plant; Sequence Homology, Amino Acid; Terpenes; Transcription, Genetic; Transferases

This paper studied the behavioral responses of Dendrolimus superans larvae and adults to Z-jasmone, methyl jasmonate (MeJA) and methyl salicylate (MeSA), and to Larix gmelinii seedlings treated with different elicitors including mechanic wounding, insect feeding, jasmonic acid (JA), salicylic acid (SA), Z-jasmone, MeJA, MeSA, and JA + SA. The results showed that D. superans larvae were repelled by MeJA and MeSA at the concentrations of 0.1%-10% V/V. L. gmelinii seedlings were induced resistance by wounding, JA, MeJA, Z-jasmone and MeSA, which decreased the feeding selection of D. superans larvae. D. superans adults exploited evident electroantennogram (EAG) responses to Z-jasmone and MeSA, and the sensitivity of the females was enhanced with the increasing concentration of Z-jasmone and MeSA. Significantly low amount of eggs was observed on the L. gmelinii seedlings treated with test elicitors.

Topics: Acetates; Animals; Cyclopentanes; Insecta; Larix; Larva; Oviposition; Oxylipins; Plant Growth Regulators; Seedlings; Smell

Symbiotic nitrogen fixation with nitrogen-fixing bacteria in the root nodules is a distinctly beneficial metabolic process in legume plants. Legumes control the nodule number and nodulation zone through a systemic negative regulatory system between shoot and root. Mutation in the soybean NTS gene encoding GmNARK, a CLAVATA1-like serine/threonine receptor-like kinase, causes excessive nodule development called hypernodulation. To examine the effect of nts mutation on the gene expression profile in the leaves, suppression subtractive hybridization was performed with the trifoliate leaves of nts mutant 'SS2-2' and the wild-type (WT) parent Sinpaldalkong2, and 75 EST clones that were highly expressed in the leaves of the SS2-2 mutant were identified. Interestingly, the expression of jasmonate (JA)-responsive genes such as vspA, vspB, and Lox2 were upregulated, whereas that of a salicylate-responsive gene PR1a was suppressed in the SS2-2 mutant. In addition, the level of JA was about two-fold higher in the leaves of the SS2-2 mutant than in those of the WT under natural growth conditions. Moreover, the JA-responsive gene expression persists in the leaves of SS2-2 mutant without rhizobia infection in the roots. Taken together, our results suggest that the nts mutation increases JA synthesis in mature leaves and consequently leads to constitutive expression of JA-responsive genes which is irrelevant to hypernodulation in the root.

Topics: Acetates; Clone Cells; Cyclopentanes; Expressed Sequence Tags; Gene Expression Regulation, Plant; Gene Library; Genes, Plant; Glycine max; Mutation; Nucleic Acid Hybridization; Oxylipins; Phenotype; Plant Leaves; Plant Proteins; Root Nodules, Plant; Up-Regulation

The Arabidopsis thaliana floral homeotic gene AGAMOUS (AG) plays a central role in reproductive organ (stamen and carpel) development. AG RNA is expressed in the center of floral primordia from a time prior to the initiation of stamen and carpel primordia until late in flower development. While early AG expression acts in specification of stamens and carpels, the role, if any, of continued AG expression in later flower development is unknown. To examine the timing of AG action and its possible late-stage functions, we performed a series of time-course experiments using a transgenic line with inducible AG activity in an ag homozygous mutant background. We show that AG controls late-stage stamen development, including anther morphogenesis and dehiscence, as well as filament formation and elongation. We further show that AG coordinates late stamen maturation by controlling a biosynthetic gene of the lipid-derived phytohormone jasmonic acid (JA). Expression analysis and in vivo binding of AG indicate that AG directly regulates the transcription of a catalytic enzyme of JA, DEFECTIVE IN ANTHER DEHISCENCE1. Our results indicate that stamen identity and differentiation control by AG is achieved by the regulation of different transcriptional cascades in different floral stages, with organ specification induced early, followed by phytohormone biosynthesis to coordinate stamen maturation.

Topics: Acetates; AGAMOUS Protein, Arabidopsis; Arabidopsis; Arabidopsis Proteins; Catalysis; Cell Nucleus; Cyclopentanes; Dexamethasone; Flowers; Gene Expression Regulation, Plant; Genes, Plant; Linoleic Acid; Oxylipins; Phospholipases A; Phospholipases A1; Promoter Regions, Genetic; RNA, Messenger; Time Factors

Coronalon (6-ethyl indanoyl isoleucine), a synthetic jasmonate mimic, is known to regulate levels of transcripts and secondary metabolites that are commonly elicited by methyl jasmonate (MeJA) in a variety of plants. The ability of coronalon and its derivative (In-L-Ile-Me) to elicit MeJA-activated transcriptional and defence responses [nicotine and trypsin proteinase inhibitors (TPIs)] was compared in treated and systemic untreated tissues of wild-type (WT) and NaLOX3-silenced Nicotiana attenuata plants which are unable to activate either local or systemic defence responses. Coronalon and its derivative significantly regulated 71% and 86% of genes up-regulated by MeJA and 53% and 66% of the genes down-regulated by MeJA in the treated leaves, but only 3% and 7% of all regulated genes in untreated, but phylotactically connected, leaves of WT plants. Consistent with their ability to elicit transcriptional responses in treated tissues, coronalon and In-L-Ile-Me increased nicotine and TPIs when applied to the tissues in which these metabolites are produced, namely roots and leaves. However, treating roots elicited TPI activity in leaves in both WT and NaLOX3-silenced plants, suggesting that mimics can be transported apoplastically from roots to leaves in the xylem. This response was lower in NaLOX3-silenced plants, suggesting that the ability of coronalon and In-L-Ile-Me to elicit TPI responses in leaves after root treatments requires intact jasmonic acid (JA) signalling. Treating leaves did not elicit detectable changes in endogenous JA levels but did decrease free salicylic acid contents. It is concluded that coronalon and In-L-Ile-Me elicit jasmonate responses in treated tissues and could be valuable tools for dissecting local and systemic jasmonate signalling networks in plants.

Topics: Acetates; Cyclopentanes; Gene Expression Regulation, Plant; Gene Silencing; Host-Pathogen Interactions; Indans; Isoleucine; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Leaves; Plants, Genetically Modified; Salicylic Acid

Chemically synthesized 2-hydroxyethyl jasmonate (HEJA) was for the first time employed to induce the ginsenoside biosynthesis and to manipulate the product heterogeneity in plant cell cultures. The dose response and timing of HEJA elicitation were investigated in cell suspension cultures of Panax notoginseng. The optimal concentration and timing of HEJA addition for both cell growth and ginsenoside accumulation was identified to be 200 microM added on day 4. It was interestingly found that HEJA could stimulate ginsenosides biosynthesis and change their heterogeneity more efficiently than methyl jasmonate (MJA), i.e., the total ginsenoside content and the Rb/Rg ratio increased about 60 and 30% with HEJA elicitation than that by MJA, respectively. The activity of Rb1 biosynthetic enzyme, i.e., UDPG-ginsenoside Rd glucosyltransferase (UGRdGT), was also higher in the former case. A maximal production titer of ginsenoside Rg1, Re, Rb1, and Rd was 47.4+/-4.8, 52.3+/-4.4, 190+/-18, and 12.1+/-2.5 mg/l with HEJA elicitation, which was about 1.3-, 1.3-, 1.7-, and 2.1-fold than that using MJA, respectively. Early signal events in plant defense response, including oxidative burst and jasmonic acid (JA) biosynthesis, were also examined. Levels of H2O2 and NO in medium and L-phenylalanine ammonia lyase activity in cells were not affected by addition of MJA and HEJA. On the other hand, the JA content in cells was increased with external jasmonates elicitation, and it was inhibited with the addition of JA biosynthesis inhibitors. The results suggest that oxidative burst might not be involved in the jasmonates-elicited signal transduction pathway, and MJA and HEJA may induce the ginsenoside biosynthesis via induction of endogenous JA biosynthesis and key enzymes (such as UGRdGT) in the ginsenoside biosynthetic pathway of P. notoginseng cells. The information is useful for hyperproduction of plant-specific heterogeneous products.

Topics: Acetates; Biotechnology; Cells, Cultured; Culture Media; Cyclopentanes; Ginsenosides; Oxylipins; Panax; Signal Transduction

Heterotrimeric G proteins have been previously linked to plant defense; however a role for the Gbetagamma dimer in defense signaling has not been described to date. Using available Arabidopsis (Arabidopsis thaliana) mutants lacking functional Galpha or Gbeta subunits, we show that defense against the necrotrophic pathogens Alternaria brassicicola and Fusarium oxysporum is impaired in Gbeta-deficient mutants while Galpha-deficient mutants show slightly increased resistance compared to wild-type Columbia ecotype plants. In contrast, responses to virulent (DC3000) and avirulent (JL1065) strains of Pseudomonas syringae appear to be independent of heterotrimeric G proteins. The induction of a number of defense-related genes in Gbeta-deficient mutants were severely reduced in response to A. brassicicola infection. In addition, Gbeta-deficient mutants exhibit decreased sensitivity to a number of methyl jasmonate-induced responses such as induction of the plant defensin gene PDF1.2, inhibition of root elongation, seed germination, and growth of plants in sublethal concentrations of methyl jasmonate. In all cases, the behavior of the Galpha-deficient mutants is coherent with the classic heterotrimeric mechanism of action, indicating that jasmonic acid signaling is influenced by the Gbetagamma functional subunit but not by Galpha. We hypothesize that Gbetagamma acts as a direct or indirect enhancer of the jasmonate signaling pathway in plants.

Topics: Acetates; Alternaria; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Fusarium; GTP-Binding Protein alpha Subunits; GTP-Binding Protein beta Subunits; GTP-Binding Protein gamma Subunits; Heterotrimeric GTP-Binding Proteins; Immunity, Innate; Oxylipins; Protein Subunits; Pseudomonas syringae; Seedlings

Germins and germin-like proteins (GLPs) are known to function in pathogen resistance, but their involvement in defense against insect herbivores is poorly understood. In the native tobacco Nicotiana attenuata, attack from the specialist herbivore Manduca sexta or elicitation by adding larval oral secretions (OS) to wounds up-regulates transcripts of a GLP. To understand the function of this gene, which occurs as a single copy, we cloned the full-length NaGLP and silenced its expression in N. attenuata by expressing a 250-bp fragment in an antisense orientation with an Agrobacterium-based transformation system and by virus-induced gene silencing (VIGS). Homozygous lines harboring a single insert and VIGS plants had significantly reduced constitutive (measured in roots) and elicited NaGLP transcript levels (in leaves). Silencing NaGLP improved M. sexta larval performance and Tupiocoris notatus preference, two native herbivores of N. attenuata. Silencing NaGLP also attenuated the OS-induced hydrogen peroxide (H(2)O(2)), diterpene glycosides, and trypsin proteinase inhibitor responses, which may explain the observed susceptibility of antisense or VIGS plants to herbivore attack and increased nicotine contents, but did not influence the OS-elicited jasmonate and salicylate bursts, or the release of the volatile organic compounds (limonene, cis-alpha-bergamotene, and germacrene-A) that function as an indirect defense. This suggests that NaGLP is involved in H(2)O(2) production and might also be related to ethylene production and/or perception, which in turn influences the defense responses of N. attenuata via H(2)O(2) and ethylene-signaling pathways.

Topics: Acetates; Amino Acid Sequence; Animals; Cyclopentanes; Diterpenes; DNA, Complementary; Gene Expression Regulation, Plant; Gene Silencing; Glycoproteins; Heteroptera; Hydrogen Peroxide; Manduca; Molecular Sequence Data; Nicotiana; Nicotine; Oxylipins; Plant Proteins; Protease Inhibitors; Salicylates; Sequence Alignment; Sequence Analysis, DNA

Root hair formation is an important model with which to study cell patterning and differentiation in higher plants. Ethylene and auxin are critical regulators of root hair development. The role of jasmonates (JAs) was examined in Arabidopsis root hair development as well as their interactions with ethylene in this process. The results have shown that both methyl jasmonate (MeJA) and jasmonic acid (JA) have a pronounced effect on promoting root hair formation. However, the effect of MeJA and JA on root hair formation was blocked by ethylene inhibitors Ag+ or aminoethoxyvinylglycine (AVG). The stimulatory effects of MeJA and JA were also diminished in ethylene-insensitive mutants etr1-1 and etr1-3. Furthermore, the JA biosynthesis inhibitors ibuprofen and salicylhydroxamic acid (SHAM) suppressed 1-aminocyclopropane-1-carboxylic acid (ACC)-induced root hair formation, and decreased the root hairs in seedlings of the ethylene over-producing mutant eto1-1. These results suggested that JAs promote root hair formation, through an interaction with ethylene.

Topics: Acetates; Arabidopsis; Cyclopentanes; Ethylenes; Oxylipins; Plant Roots

The responses of Arabidopsis accessions and characterized genotypes were used to explore components in the early defense responses to the soilborne fungus Verticillium longisporum. V. longisporum susceptibility was found to be a complex trait, in which different disease phenotypes, such as stunting, altered flowering time, weight loss, and chlorosis were perceived differently across genotypes. A Bay-0 x Shahdara recombinant inbred line population was used to identify two loci on chromosomes 2 and 3 of Bay-0 origin that caused enhanced chlorosis after V. longisporum challenge. Furthermore, the observation that a mutation in RFO1 in Col-0 resulted in susceptibility whereas the natural rfo1 allele in Ty-0 showed a high degree of resistance to the pathogen supports the hypothesis that several resistance quantitative trait loci reside among Arabidopsis accessions. Analysis of mutants impaired in known pathogen response pathways revealed an enhanced susceptibility in ein2-1, ein4-1, ein6-1, esa1-1, and pad1-1, but not in other jasmonic acid (JA)-, ethylene (ET)-, or camalexin-deficient mutants, suggesting that V. longisporum resistance is regulated via a hitherto unknown JA- and ET-associated pathway. Pretreatments with the ET precursor 1-aminocyclo-propane-1-carboxylic acid (ACC) or methyl jasmonate (MeJA) caused enhanced resistance to V. longisporum. Mutants in the salicylic acid (SA) pathway (eds1-1, NahG, npr1-3, pad4-1, and sid2-1) did not show enhanced susceptibility to V. longisporum. In contrast, the more severe npr1-1 allele displayed enhanced V. longisporum susceptibility and decreased responses to ACC or MeJA pretreatments. This shows that cytosolic NPR1, in addition to SA responses, is required for JA- and ET-mediated V. longisporum resistance. Expression of the SA-dependent PR-1 and PR-2 and the ET-dependent PR-4 were increased 7 days postinoculation with V. longisporum. This indicates increased levels of SA and ET in response to V. longisporum inoculation. The R-gene signaling mutant ndr1-1 was found to be susceptible to V. longisporum, which could be complemented by ACC or MeJA pretreatments, in contrast to the rfo1 T-DNA mutant, which remained susceptible, suggesting that RFO1 (Fusarium oxysporum resistance) and NDR1 (nonrace specific disease resistance 1) activate two distinct signaling pathways for V. longisporum resistance.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Cytosol; Ethylenes; Gene Expression Regulation, Plant; Genotype; Glucuronidase; Immunity, Innate; Mutation; Oxylipins; Plant Diseases; Plants, Genetically Modified; Protein Kinases; Salicylic Acid; Signal Transduction; Time Factors; Transcription Factors; Verticillium

The purpose of this study was to identify endogenous factors that induce gummosis and to show their role in gummosis in tulip (Tulipa gesneriana L. cv. Apeldoorn) stems. Using procedures to detect endogenous factors that induce gum in the stem of tulips, jasmonic acid (JA) and methyl jasmonate (JA-Me) were successfully identified using gas-liquid chromatography-mass spectrometry. Total amounts of JA and JA-Me designated as jasmonates in tulip stems were also estimated at about 70-80 ng/g fresh weight, using deuterium-labeled jasmonates as internal standards. The application of JA and JA-Me as lanolin pastes substantially induced gums in tulip stems with ethylene production. The application of ethephon, an ethylene-generating compound, however, induced no gummosis although it slightly affected jasmonate content in tulip stems. These results strongly suggest that JA and JA-Me are endogenous factors that induce gummosis in tulip stems.

Topics: Acetates; Cyclopentanes; Oxylipins; Plant Growth Regulators; Plant Stems; Polysaccharides; Tulipa

Arabidopsis thaliana contains a large number of genes that encode carboxylic acid-activating enzymes, including nine long-chain fatty acyl-CoA synthetases, four 4-coumarate:CoA ligases (4CL), and 25 4CL-like proteins of unknown biochemical function. Because of their high structural and sequence similarity with bona fide 4CLs and their highly hydrophobic putative substrate-binding pockets, the 4CL-like proteins At4g05160 and At5g63380 were selected for detailed analysis. Following heterologous expression, the purified proteins were subjected to a large scale screen to identify their preferred in vitro substrates. This study uncovered a significant activity of At4g05160 with medium-chain fatty acids, medium-chain fatty acids carrying a phenyl substitution, long-chain fatty acids, as well as the jasmonic acid precursors 12-oxo-phytodienoic acid and 3-oxo-2-(2'-pentenyl)-cyclopentane-1-hexanoic acid. The closest homolog of At4g05160, namely At5g63380, showed high activity with long-chain fatty acids and 12-oxo-phytodienoic acid, the latter representing the most efficiently converted substrate. By using fluorescent-tagged variants, we demonstrated that both 4CL-like proteins are targeted to leaf peroxisomes. Collectively, these data demonstrate that At4g05160 and At5g63380 have the capacity to contribute to jasmonic acid biosynthesis by initiating the beta-oxidative chain shortening of its precursors.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Coenzyme A Ligases; Cyclopentanes; Fatty Acids; Gene Expression Regulation, Plant; Isoenzymes; Molecular Structure; Oxylipins; Peroxisomes; Phylogeny; Plant Growth Regulators; Plant Leaves; Recombinant Fusion Proteins; Sequence Alignment

Here the effect of jasmonic acid, methyljasmonate and Na-orthovanadate on the production of resveratrol was studied in Vitis vinifera cv. Barbera cell suspension cultures. Na-orthovanadate at 0.1 mm and 1 mm concentration was efficient in promoting the production and/or accumulation and release in the culture medium of cis-resveratrol while trans-resveratrol levels were not affected by this treatment. Methyljasmonate was highly effective in stimulating both trans- and cis-resveratrol endogenous accumulation, as well as their release into the culture medium. Cis-resveratrol was absent or detected in very low amounts in the controls. Jasmonic acid was less efficient than methyljasmonate in promoting endogenous resveratrol accumulation, but it stimulated the release in the culture medium especially of cis-resveratrol. Gel analysis was performed on control and 10 microm MeJA treated cell suspensions. Results showed an up-regulation of the stilbene synthase demonstrating that MeJA stimulated the synthesis ex-novo of this protein.

Topics: Acetates; Cells, Cultured; Cyclopentanes; Oxylipins; Plant Growth Regulators; Resveratrol; Stilbenes; Time Factors; Vanadates; Vitis

The purpose of this study was to know the mechanism of jasmonates to induce gummosis in tulip (Tulipa gesneriana L. cv. Apeldoorn) shoots, especially on the focus of sugar metabolism. Gummosis in the first internode of tulip plants was induced by the application of methyl jasmonate (JA-Me, 1% w/w in lanolin) and jasmonic acid (JA, 1% w/w in lanolin) 5 days after application and strongly stimulated by the simultaneous application of ethylene-releasing compound, ethephon (2-chloroethylphosphonic acid, 1% w/w in lanolin), although ethephon alone had little effect. JA-Me stimulated ethylene production of the first internodes of tulips, ethylene production increasing up to more than 5 times at day 1 and day 3 after the application. On the other hand, application of ethephon did not increase endogenous levels of jasmonates in tulip stems. Analysis of composition of tulip gums revealed that they were consisted of glucuronoarabinoxylan with an average molecular weight of ca. 700 kDa. JA-Me strongly decreased the total amount of soluble sugars in tulip stems even in 1 day after application, being ca. 50% of initial values 5 days after application, but ethephon did not. However, both JA-Me and ethephon had almost no effect on the neutral sugar compositions of soluble sugars mainly consisting of glucose, mannose and xylose in ratio of 20:2:1 and traces of arabinose. Both JA-Me and ethephon applied exogenously stimulated senescence of tulip shoots shown by the loss of chlorophyll. These results strongly suggest that the essential factor of gummosis in tulips is jasmonates affecting the sugar metabolism in tulip shoots. The mode of action of jasmonates to induce gummosis of tulip shoots is discussed in relation to ethylene production, sugar metabolism and senescence.

Topics: Acetates; Carbohydrate Metabolism; Cell Wall; Cyclopentanes; Ethylenes; Organophosphorus Compounds; Oxylipins; Plant Stems; Signal Transduction; Tulipa

Gravitropism is explained by the Cholodny-Went hypothesis: the basipetal flow of auxin is diverted laterally. The resulting lateral auxin gradient triggers asymmetric growth. However, the Cholodny-Went hypothesis has been questioned repeatedly because the internal auxin gradient is too small to account for the observed growth asymmetry. Therefore, an additional gradient in indolyl-3-acetic acid (IAA) sensitivity has been suggested (Brauner and Hager in Planta 51:115-147, 1958). We challenged the Cholodny-Went hypothesis for gravitropism of rice coleoptiles (Oryza sativa L.) and found it to be essentially true. However, we observed, additionally, that the two halves of gravitropically stimulated coleoptiles responded differentially to the same amount of exogenous auxin: the auxin response is reduced in the upper flank but normal in the lower flank. This indicates that the auxin-gradient is amplified by a gradient of auxin responsiveness. Hormone contents were measured across the coleoptile by a GC-MS/MS technique and a gradient of jasmonate was detected opposing the auxin gradient. Furthermore, the total content of jasmonate increased during the gravitropic response. Jasmonate gradient and increase persist even when the lateral IAA gradient is inhibited by 1-N-naphtylphtalamic acid. Flooding with jasmonate delays the onset of gravitropic bending. Moreover, a jasmonate-deficient rice mutant bends more slowly and later than the wild type. We discuss a role of jasmonate as modulator of auxin responsiveness in gravitropism.

Topics: Acetates; Cotyledon; Cyclopentanes; Dose-Response Relationship, Drug; Gravitropism; Indoleacetic Acids; Models, Biological; Oryza; Oxylipins; Phthalimides; Plant Growth Regulators

Mutations in p53, a tumor suppressor gene, occur in more than half of human cancers. Therefore, we tested the hypothesis that jasmonates (novel anticancer agents) can induce death in mutated p53-expressing cells. Two clones of B-lymphoma cells were studied, one expressing wild-type (wt) p53 and the other expressing mutated p53. Jasmonic acid and methyl jasmonate (0.25-3 mM) were each equally cytotoxic to both clones, whereas mutant p53-expressing cells were resistant to treatment with the radiomimetic agent neocarzinostatin and the chemotherapeutic agent bleomycin. Neocarzinostatin and bleomycin induced an elevation in the p53 levels in wt p53-expressing cells, whereas methyl jasmonate did not. Methyl jasmonate induced mostly apoptotic death in the wt p53-expressing cells, while no signs of early apoptosis were detected in mutant p53-expressing cells. In contrast, neocarzinostatin and bleomycin induced death only in wt p53-expressing cells, in an apoptotic mode. Methyl jasmonate induced a rapid depletion of ATP in both clones. In both clones, oligomycin (a mitochondrial ATP synthase inhibitor) did not increase ATP depletion induced by methyl jasmonate, whereas inhibition of glycolysis with 2-deoxyglucose did. High glucose levels protected both clones from methyl jasmonate-induced ATP depletion (and reduced methyl jasmonate-induced cytotoxicity), whereas high levels of pyruvate did not. These results suggest that methyl jasmonate induces ATP depletion mostly by compromising oxidative phosphorylation in the mitochondria. In conclusion, jasmonates can circumvent the resistance of mutant p53-expressing cells towards chemotherapy by inducing a nonapoptotic cell death.

Topics: Acetates; Adenosine Triphosphate; Antibiotics, Antineoplastic; Bleomycin; Cell Survival; Clone Cells; Cyclopentanes; Deoxyglucose; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Humans; Immunoblotting; Lymphoma, B-Cell; Mutation; Oligomycins; Oxylipins; Plant Growth Regulators; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Zinostatin

Jasmonic acid (JA) and methyl jasmonate (MeJA), collectively termed jasmonates, are ubiquitous plant signalling compounds. Several types of stress conditions, such as wounding and pathogen infection, cause endogenous JA accumulation and the expression of jasmonate-responsive genes. Although jasmonates are important signalling components for the stress response in plants, the mechanism by which jasmonate signalling contributes to stress tolerance has not been clearly defined. A comprehensive analysis of jasmonate-regulated metabolic pathways in Arabidopsis was performed using cDNA macroarrays containing 13516 expressed sequence tags (ESTs) covering 8384 loci. The results showed that jasmonates activate the coordinated gene expression of factors involved in nine metabolic pathways belonging to two functionally related groups: (i) ascorbate and glutathione metabolic pathways, which are important in defence responses to oxidative stress, and (ii) biosynthesis of indole glucosinolate, which is a defence compound occurring in the Brassicaceae family. We confirmed that JA induces the accumulation of ascorbate, glutathione and cysteine and increases the activity of dehydroascorbate reductase, an enzyme in the ascorbate recycling pathway. These antioxidant metabolic pathways are known to be activated under oxidative stress conditions. Ozone (O3) exposure, a representative oxidative stress, is known to cause activation of antioxidant metabolism. We showed that O3 exposure caused the induction of several genes involved in antioxidant metabolism in the wild type. However, in jasmonate-deficient Arabidopsis 12-oxophytodienoate reductase 3 (opr3) mutants, the induction of antioxidant genes was abolished. Compared with the wild type, opr3 mutants were more sensitive to O3 exposure. These results suggest that the coordinated activation of the metabolic pathways mediated by jasmonates provides resistance to environmental stresses.

Topics: Acetates; Antioxidants; Arabidopsis; Ascorbic Acid; Cyclopentanes; DNA, Plant; Genes, Plant; Glucosinolates; Indoles; Models, Biological; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Oxylipins; Ozone; Sulfur

Jasmonic acid and methyl jasmonate play an essential role in plant defense responses and pollen development. Their levels are temporarily and spatially controlled in plant tissue. However, whereas jasmonate biosynthesis is well studied, metabolic pathways downstream of jasmonic acid are less understood. We studied the uptake and metabolism of jasmonic acid and methyl jasmonate in tobacco (Nicotiana tabacum) Bright Yellow-2 suspension culture. We found that upon uptake, jasmonic acid was metabolized to its Glc and gentiobiose esters, and hydroxylation at C-11 or C-12 occurred. Free hydroxylated jasmonates were the preferential fraction of the culture medium. Upon hydrolysis of methyl jasmonate to jasmonic acid, a similar set of conversions occurs. In contrast to jasmonic acid, none of its derivatives interfere with the G2/M transition in synchronized tobacco Bright Yellow-2 cells.

Topics: Acetates; Cell Division; Cells, Cultured; Cyclopentanes; Disaccharides; G2 Phase; Glucose; Kinetics; Mitosis; Nicotiana; Oxylipins

Novel hydroxyl-containing jasmonate derivatives were chemically synthesized and evaluated by bioassay as potential elicitors for stimulating the biosynthesis of plant secondary metabolites. A suspension culture of Taxus chinensis, which produces a bioactive taxoid, taxuyunnanine C (Tc), was taken as a model plant cell system. Experiments on the timing of addition of jasmonates and dose response indicated that day 7 and 100 microM was the optimal elicitation time and concentration, respectively, for both cell growth and Tc accumulation. Tc accumulation was increased more in the presence of novel hydroxyl-containing jasmonates compared to that with methyljasmonate (MJA) addition. For example, addition of 100 microM 2,3-dihydroxypropyl jasmonate on day 7 led to a very high Tc content of 47.2 +/- 0.5 mg/g (at day 21), whereas the Tc content was 29.2 +/- 0.6 mg/g (on the same day) with addition of 100 microM MJA. Quantitative structure-activity analysis of various jasmonates suggests that the optimal lipophilicity and the number of hydroxyl groups may be two important factors affecting their elicitation activity. In addition, the jasmonate elicitors were found to induce plant defense responses, including oxidative burst and activation of L-phenylalanine ammonia lyase (PAL). Interestingly, a higher level of H(2)O(2) production and PAL activity was detected with elicitation by the synthesized jasmonates compared with that by MJA, which corresponded well to the superior stimulating activity in the former. This work indicates that the newly synthesized hydroxyl-containing jasmonates can act as powerful inducing signals for secondary metabolite biosynthesis in plant cell cultures.

Topics: Acetates; Cell Line; Cyclopentanes; Esters; Glucosides; Hydrogen Peroxide; Molecular Structure; Oxylipins; Phenylalanine Ammonia-Lyase; Plant Growth Regulators; Quantitative Structure-Activity Relationship; Taxoids; Taxus

We transformed the native tobacco, Nicotiana attenuata, to silence its lipoxygenase, hydroperoxide lyase, and allene oxide synthase genes in order to inhibit oxylipin signaling, known to mediate the plant's direct and indirect defenses. When planted into native habitats, lipoxygenase-deficient plants were more vulnerable to N. attenuata's adapted herbivores but also attracted novel herbivore species, which fed and reproduced successfully. In addition to highlighting the value of genetically silencing plants to study ecological interactions in nature, these results show that lipoxygenase-dependent signaling determines host selection for opportunistic herbivores and that induced defenses influence herbivore community composition.

Topics: Acetates; Aldehyde-Lyases; Animals; Bridged Bicyclo Compounds; Coleoptera; Cyclopentanes; Cytochrome P-450 Enzyme System; Ecosystem; Female; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Silencing; Hemiptera; Hexobarbital; Insecta; Intramolecular Oxidoreductases; Lipoxygenase; Manduca; Nicotiana; Nicotine; Oligonucleotide Array Sequence Analysis; Oviposition; Oxylipins; Signal Transduction; Terpenes; Transformation, Genetic

Chitinase is a pathogenesis-related protein that hydrolyzes chitin, a major component of fungal cell walls. Two-week-old rice seedling leaf, leaf sheath and root tissues responded to an exogenous treatment by jasmonic acid (JA) with induction of the chitinases as determined by immunoblot analysis using an anti-endochitinase antibody. Induced accumulation of these chitinases was observed within 24 to 48 h in the leaf sheaths, leaves and roots. Besides, ethylene generator ethephon and abiotic stressor copper could also induce chitinases accumulation among various plant hormones and stress agents examined. Cycloheximide effectively blocked their accumulation by JA, suggesting that de novo protein synthesis is required. Partial blockage of the induced accumulation of chitinases by NADPH oxidase inhibitor and free radical scavengers suggested involvement of reactive oxygen species. Moreover, induced accumulation of these chitinases also by methyl jasmonate and certain protein phosphatase inhibitors indicated their potential importance and wider role in rice seedlings.

Topics: Acetates; Chitinases; Cycloheximide; Cyclopentanes; Enzyme Inhibitors; Ethylenes; Onium Compounds; Organophosphorus Compounds; Oryza; Oxylipins; Phosphoprotein Phosphatases; Plant Growth Regulators; Plant Structures; Reactive Oxygen Species

Arabidopsis does not support the growth and asexual reproduction of the barley pathogen, Blumeria graminis f. sp. hordei Bgh). A majority of germlings fail to penetrate the epidermal cell wall and papillae. To gain additional insight into this interaction, we determined whether the salicylic acid (SA) or jasmonate (JA)/ethylene (ET) defence pathways played a role in blocking barley powdery mildew infections. Only the eds1 mutant and NahG transgenics supported a modest increase in penetration success by the barley powdery mildew. We also compared the global gene expression patterns of Arabidopsis inoculated with the non-host barley powdery mildew to those inoculated with a virulent, host powdery mildew, Erysiphe cichoracearum. Genes repressed by inoculations with non-host and host powdery mildews relative to non-inoculated control plants accounted for two-thirds of the differentially expressed genes. A majority of these genes encoded components of photosynthesis and general metabolism. Consistent with this observation, Arabidopsis growth was inhibited following inoculation with Bgh, suggesting a shift in resource allocation from growth to defence. A number of defence-associated genes were induced during both interactions. These genes likely are components of basal defence responses, which do not effectively block host powdery mildew infections. In addition, genes encoding defensins, anti-microbial peptides whose expression is under the control of the JA/ET signalling pathway, were induced exclusively by non-host pathogens. Ectopic activation of JA/ET signalling protected Arabidopsis against two biotrophic host pathogens. Taken together, these data suggest that biotrophic host pathogens must either suppress or fail to elicit the JA/ET signal transduction pathway.

Topics: Acetates; Arabidopsis; Ascomycota; Cyclopentanes; Defensins; Ethylenes; Gene Expression Regulation, Plant; Hordeum; Immunity, Innate; Oxylipins; Plant Diseases; Plant Leaves; Plants, Genetically Modified; Salicylic Acid; Signal Transduction

A monoclonal antibody (McAb) against methyl jasmonate (MeJA) was prepared and characterized. The McAb, J2-4B, was derived from an immunogen in which the C1-COOH of jasmonic acid (JA) was conjugated to the -NH2 of keyhole limpet hemocyanin (KLH). The McAb showed a higher recognition ability to methyl esters of JA than to its free acids. The integrity of a pentenyl in JA molecule was necessary for the recognition of McAb. Hydrogenation at C-9 and C-10 (dihydrojasmonic acid, 2H-JA) or eliminating the methyl group at C-12 (JAS-25) significantly abolished the binding force of JA molecule with the McAb. Some structural or functional analogues or precursor of JA, such as cucurbic acid, theobroxide, coronatine, and linolenic acid, could not be recognized by the McAb. The McAb has been used to set up a competitive enzyme-linked immunosorbent assay (ELISA) with a linearity range from 2.06 to 500 pmol of MeJA. Using this method, the fluctuations of JA content in florets during anthesis of wheat and Italian ryegrass were analyzed. Results showed that JA level increased obviously as the florets approaching to opening, arrived at a "peak" value at full opening and decreased sharply afterwards.

Topics: Acetates; Animals; Antibodies, Monoclonal; Cell Line, Tumor; Cyclopentanes; Enzyme-Linked Immunosorbent Assay; Flowers; Lolium; Mice; Molecular Structure; Oxylipins; Triticum

12-Hydroxyjasmonate, also known as tuberonic acid, was first isolated from Solanum tuberosum and was shown to have tuber-inducing properties. It is derived from the ubiquitously occurring jasmonic acid, an important signaling molecule mediating diverse developmental processes and plant defense responses. We report here that the gene AtST2a from Arabidopsis thaliana encodes a hydroxyjasmonate sulfotransferase. The recombinant AtST2a protein was found to exhibit strict specificity for 11- and 12-hydroxyjasmonate with K(m) values of 50 and 10 microm, respectively. Furthermore, 12-hydroxyjasmonate and its sulfonated derivative are shown to be naturally occurring in A. thaliana. The exogenous application of methyljasmonate to A. thaliana plants led to increased levels of both metabolites, whereas treatment with 12-hydroxyjasmonate led to increased level of 12-hydroxyjasmonate sulfate without affecting the endogenous level of jasmonic acid. AtST2a expression was found to be induced following treatment with methyljasmonate and 12-hydroxyjasmonate. In contrast, the expression of the methyljasmonate-responsive gene Thi2.1, a marker gene in plant defense responses, is not induced upon treatment with 12-hydroxyjasmonate indicating the existence of independent signaling pathways responding to jasmonic acid and 12-hydroxyjasmonic acid. Taken together, the results suggest that the hydroxylation and sulfonation reactions might be components of a pathway that inactivates excess jasmonic acid in plants. Alternatively, the function of AtST2a might be to control the biological activity of 12-hydroxyjasmonic acid.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Blotting, Northern; Chromatography, Liquid; Cloning, Molecular; Cyclopentanes; Electrophoresis, Polyacrylamide Gel; Kinetics; Mass Spectrometry; Molecular Sequence Data; Oxylipins; Plants, Genetically Modified; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sequence Homology, Amino Acid; Sulfotransferases

Oxylipins of the jasmonate pathway and synthetic functional analogs have been analyzed for their elicitor-like activities in an assay based on the induced accumulation of glyceollins, the phytoalexins of soybean (Glycine max L.), in cell suspension cultures of this plant. Jasmonic acid (JA) and its methyl ester showed weak phytoalexin-inducing activity when compared to an early jasmonate biosynthetic precursor, 12-oxo-phytodienoic acid (OPDA), as well as to the bacterial phytotoxin coronatine and certain 6-substituted indanoyl-L-isoleucine methyl esters, which all were highly active. Interestingly, different octadecanoids and indanoyl conjugates induced the accumulation of transcripts of various defense-related genes to different degrees, indicating distinct induction competencies. Therefore, these signaling compounds and mimics were further analyzed for their effects on signal transduction elements, such as the transient enhancement of the cytosolic Ca2+ concentration and MAP kinase activation, which are known to be initiated by a soybean pathogen-derived beta-glucan elicitor. In contrast to the beta-glucan elicitor, none of the other compounds tested triggered these early signaling elements. Moreover, endogenous levels of OPDA and JA in soybean cells were shown to be unaffected after treatment with beta-glucans. Thus, OPDA and JA, which are functionally mimicked by coronatine and a variety of 6-substituted derivatives of indanoyl-L-isoleucine methyl ester, represent highly efficient signaling compounds of a lipid-based pathway not deployed in the beta-glucan elicitor-initiated signal transduction.

Topics: Acetates; Amino Acids; Benzopyrans; Cyclopentanes; Fatty Acids, Unsaturated; Gene Expression Regulation, Plant; Glycine max; Indenes; Mitogen-Activated Protein Kinases; Molecular Mimicry; Oxylipins; Plant Growth Regulators; Pterocarpans; RNA, Messenger; Signal Transduction

Jasmonate (JA) is a signaling compound essential for anther development and pollen fertility in Arabidopsis. Mutations that block the pathway of JA synthesis result into male sterility. To understand the processes of anther and pollen maturation, we used microarray and differential display approaches to compare gene expression pattern in anthers of wild-type Arabidopsis and the male-sterile mutant, opr3. Microarray experiment revealed 25 genes that were up-regulated more than 1.8-fold in wild-type anthers as compared to mutant anthers. Experiments based on differential display identified 13 additional genes up-regulated in wild-type anthers compared to opr3 for a total of 38 differentially expressed genes. Searches of the Arabidopsis and non-redundant databases disclosed known or likely functions for 28 of the 38 genes identified, while 10 genes encode proteins of unknown function. Northern blot analysis of eight representative clones as probes confirmed low expression in opr3 anthers compared with wild-type anthers. JA responsiveness of these same genes was also investigated by northern blot analysis of anther RNA isolated from wild-type and opr3 plants, In these experiments, four genes were induced in opr3 anthers within 0.5-1 h of JA treatment while the remaining genes were up-regulated only 1-8 h after JA application. None of these genes was induced by JA in anthers of the coil mutant that is deficient in JA responsiveness. The four early-induced genes in opr3 encode lipoxygenase, a putative bHLH transcription factor, epithiospecifier protein and an unknown protein. We propose that these and other early components may be involved in JA signaling and in the initiation of developmental processes. The four late genes encode an extensin-like protein, a peptide transporter and two unknown proteins, which may represent components required later in anther and pollen maturation. Transcript profiling has provided a successful approach to identify genes involved in anther and pollen maturation in Arabidopsis.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Blotting, Northern; Cyclopentanes; DNA, Complementary; Flowers; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes, Plant; Molecular Sequence Data; Mutation; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Growth Regulators; Polymerase Chain Reaction; RNA, Messenger; Sequence Analysis, DNA; Sequence Homology, Amino Acid

Plants under stress from both biotic and abiotic sources produce increased levels of ethylene, which is perceived by ethylene receptors and triggers cellular responses further downstream. Protein phosphorylation and dephosphorylation were implicated in the regulation of ethylene induction by stresses based on studies using protein kinase and phosphatase inhibitors. However, the kinase(s) involved remains to be determined. Using a conditional gain-of-function transgenic system, we demonstrate that the activation of SIPK, a tobacco mitogen-activated protein kinase (MAPK), by NtMEK2DD, an active mutant of the upstream kinase of SIPK, resulted in a dramatic increase in ethylene production. The increase in ethylene after the activation of SIPK coincided with a dramatic increase in 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) activity, which was followed by the activation of a subgroup of ACS and ACC oxidase (ACO) genes, suggesting that either the activation of unidentified ACS(s) or post-transcriptional regulation is involved. Infection with Tobacco mosaic virus (TMV), which is known to activate the SIPK cascade and induce ethylene biosynthesis, also induced the same ACSs and ACOs. After ethylene production in NtMEK2DD plants, strong activation of ETHYLENE-RESPONSE FACTOR (ERF) genes was observed, similar to the effect in NN tobacco plants infected with TMV. In contrast to previous reports, no major increase in jasmonic acid (JA) and methyl jasmonate (MJ) was detected after the activation of SIPK/WIPK in NtMEK2DD transgenic plants. These results suggest that the induction of ethylene but not JA/MJ is involved in plant defense responses mediated by the NtMEK2-SIPK/WIPK pathway.

Topics: Acetates; Amino Acid Oxidoreductases; Cyclopentanes; Dexamethasone; Enzyme Activation; Ethylenes; Lyases; Mitogen-Activated Protein Kinases; Nicotiana; Oxylipins; Plant Proteins; Plants, Genetically Modified; Stress, Mechanical; Tobacco Mosaic Virus

Lipoxygenases (LOXs) catalyze the formation of fatty acid hydroperoxides involved in responses to stresses. This study examines the expression of a non-traditional dual positional specific maize LOX in response to wounding or methyl jasmonate (MeJA). Full-length maize LOX cDNA was expressed in Escherichia coli, and recombinant LOX was purified and characterized enzymatically. RP-HPLC and GC-MS analysis showed that the purified LOX converts alpha-linolenic acid into 13-hydroperoxylinolenic acid and 9-hydroperoxylinolenic acid in a 6:4 ratio. LOX mRNA accumulated rapidly and transiently in response to wounding reaching a peak of expression about 3 h after wounding. This increase followed an initial increase in endogenous jasmonic acid (JA) 1 h after wounding (JA burst). However, the expression of LOX induced by MeJA lasted longer than the expression induced by wounding, and the MeJA-induced expression seemed to be biphasic pattern composed of early and late phases. The expression of LOX in the presence of inhibitors of JA biosynthesis was not completely inhibited, but delayed in wound response and the expression period was shortened in MeJA response. These results suggest that wound-responsive JA burst may trigger the early phase of LOX expression which facilitates biosynthesis of endogenous JA through its 13-LOX activity, and subsequently leads to the activation of the late phase LOX expression in MeJA-treated maize seedlings. Implications of dual positional specificity of maize LOX in the observed expression kinetics are discussed.

Topics: Acetates; Amino Acid Sequence; Aspirin; Chromatography, High Pressure Liquid; Cyclopentanes; Gas Chromatography-Mass Spectrometry; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Lipoxygenase; Lipoxygenase Inhibitors; Molecular Sequence Data; Oxylipins; Phylogeny; Plant Growth Regulators; Pyrazoles; Seedlings; Sequence Homology, Amino Acid; Stress, Mechanical; Structure-Activity Relationship; Substrate Specificity; Time Factors; Zea mays

The octadecanoid signaling pathway has been shown to play an important role in plant defense against various chewing insects and some pathogenic fungi. Here, we examined the interaction of a cell-content feeding arachnid herbivore, the two-spotted spider mite (Tetranychus urticae Koch), with cultivated tomato (Lycopersicon esculentum) and an isogenic mutant line (defenseless-1 [def-1]) that is deficient in the biosynthesis of the octadecanoid pathway-derived signal, jasmonic acid (JA). Spider mite feeding and fecundity on def-1 plants was significantly greater than on wild-type plants. Decreased resistance of def-1 plants was correlated with reduced JA accumulation and expression of defensive proteinase inhibitor (PI) genes, which were induced in mite-damaged wild-type leaves. Treatment of def-1 plants with methyl-JA restored resistance to spider mite feeding and reduced the fecundity of female mites. Plants expressing a 35S::prosystemin transgene that constitutively activates the octadecanoid pathway in a Def-1-dependent manner were highly resistant to attack by spider mites and western flower thrips (Frankliniella occidentalis), another cell-content feeder of economic importance. These findings indicate that activation of the octadecanoid signaling pathway promotes resistance of tomato to a broad spectrum of herbivores. The techniques of amplified fragment length polymorphism (AFLP) and bulk segregant analysis were used to map the Def-1 gene to a region on the long arm of chromosome 3 that is genetically separable from the map position of known JA biosynthetic genes. Tight linkage of Def-1 to a T-DNA insertion harboring the maize (Zea mays) Dissociation transposable element suggests a strategy for directed transposon tagging of the gene.

Topics: Acetates; Animals; Arachnida; Chromosome Mapping; Cyclopentanes; Female; Genotype; Immunity, Innate; Insecta; Mutation; Oxylipins; Plant Diseases; Plant Growth Regulators; Signal Transduction; Solanum lycopersicum; Stearic Acids

The activation of mitogen-activated protein kinases (MAPKs) has been previously implicated in signal transduction during plant responses to pathogen attack as well as to various environmental stresses. We have isolated from rice a new MAPK cDNA, OsBIMK1 ( O ryza s ativa L. BTH-induced MAPK 1), which encodes a 369-amino-acid protein with moderate to high nucleotide sequence similarity to previously reported plant MAPK genes. OsBIMK1 contains all 11 of the MAPK conserved subdomains and the phosphorylation-activation motif, TEY. We analyzed in detail the expression of OsBIMK1 upon treatment with various chemical and biological inducers of resistance responses in rice and in both incompatible and compatible interactions between rice and Magnaporthe grisea. Expression of OsBIMK1 was activated rapidly upon treatment with benzothiadiazole (BTH) as well as with dichloroisonicotinic acid, probenazole, jasmonic acid and its methyl ester, Pseudomonas syringae pv. syringae, or wounding. Expression of OsBIMK1 was induced rapidly during the first 36 h after inoculation with M. grisea in BTH-treated rice seedlings and in an incompatible interaction between M. grisea and a blast-resistant rice genotype. BTH treatment induced a systemic activation of OsBIMK1 expression. These results suggest that OsBIMK1 plays an important role in rice disease resistance.

Topics: Acetates; Amino Acid Sequence; Base Sequence; Cloning, Molecular; Cyclopentanes; DNA, Complementary; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Immunity, Innate; Isonicotinic Acids; Magnaporthe; Mitogen-Activated Protein Kinases; Molecular Sequence Data; Oryza; Oxylipins; Phylogeny; Plant Diseases; Pseudomonas; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Signal Transduction; Stress, Mechanical; Thiadiazoles; Thiazoles

Suppressors produced by Mycosphaerella pinodes are glycopeptides to block pea defense responses induced by elicitors. A clone, S64, was isolated as cDNA for suppressor-inducible gene from pea epicotyls. The treatment of pea epicotyls with suppressor alone induced an increase of S64 mRNA within 1 h, and it reached a maximum level at 3 h after treatment. The induction was not affected by application of the elicitor, indicating that the suppressor has a dominant action to regulate S64 gene expression. S64 was also induced by inoculation with a virulent pathogen, M. pinodes, but not by inoculation with a non-pathogen, Ascochyta rabiei, nor by treatment with fungal elicitor. The deduced structure of S64 showed high homology to 12-oxophytodienoic acid reductase (OPR) in Arabidopsis thaliana. A recombinant protein derived from S64 had OPR activity, suggesting compatibility-specific activation of the octadecanoid pathway in plants. Treatment with jasmonic acid (JA) or methyl jasmonic acid, end products of the octadecanoid pathway, inhibited the elicitor-induced accumulation of PAL mRNA in pea. These results indicate that the suppressor-induced S64 gene expression leads to the production of JA or related compounds, which might contribute to the establishment of compatibility by inhibiting the phenylpropanoid biosynthetic pathway.

Topics: Acetates; Amino Acid Sequence; Cloning, Molecular; Cyclopentanes; Desiccation; Fungi; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Molecular Sequence Data; NADH, NADPH Oxidoreductases; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Oxylipins; Phenylalanine Ammonia-Lyase; Phylogeny; Pisum sativum; Plant Growth Regulators; Plant Proteins; Recombinant Proteins; RNA, Messenger; Sequence Homology, Amino Acid; Signal Transduction

Polyamines are small ubiquitous molecules that have been involved in nearly all developmental processes, including the stress response. Nevertheless, no direct evidence of a role of polyamines in the wound response has been described. We have studied the expression of genes involved in polyamine biosynthesis in response to mechanical injury. An increase in the expression of the arginine decarboxylase 2 (ADC2) gene in response to mechanical wounding and methyl jasmonate (JA) treatment in Arabidopsis was detected by using DNA microarray and RNA gel-blot analysis. No induction was observed for the ADC1 gene or other genes coding for spermidine and spermine synthases, suggesting that ADC2 is the only gene of polyamine biosynthesis involved in the wounding response mediated by JA. A transient increase in the level of free putrescine followed the increase in the mRNA level for ADC2. A decrease in the level of free spermine, coincident with the increase in putrescine after wounding, was also observed. Abscisic acid effected a strong induction on ADC2 expression and had no effect on ADC1 expression. Wound-induction of ADC2 mRNA was not prevented in the JA-insensitive coi1 mutant. The different pattern of expression of ADC2 gene in wild-type and coi1 mutant might be due to the dual regulation of ADC2 by abscisic acid and JA signaling pathways. This is the first direct evidence of a function of polyamines in the wound-response, and it opens a new aspect of polyamines in plant biology.

Topics: Abscisic Acid; Acetates; Arabidopsis; Carboxy-Lyases; Cyclopentanes; Enzyme Induction; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Mutation; Oligonucleotide Array Sequence Analysis; Oxylipins; Polyamines; Signal Transduction; Stress, Mechanical

Coronatine-inducible tyrosine aminotransferase (TAT), which catalyses the transamination from tyrosine to p-hydroxyphenylpyruvate, is the first enzyme of a pathway leading via homogentisic acid to plastoquinone and tocopherols, the latter of which are known to be radical scavengers in plants. TAT can be also induced by the octadecanoids methyl jasmonate (MeJA) and methyl-12-oxophytodienoic acid (MeOPDA), as well as by wounding, high light, UV light and the herbicide oxyfluorfen. In order to elucidate the role of octadecanoids in the process of TAT induction in Arabidopsis thaliana (L.) Heynh., the jasmonate-deficient mutant delayed dehiscence (dde1) was used, in which the gene for 12-oxophytodienoic acid reductase 3 is disrupted. The amount of immunodetectable TAT was low. The enzyme was still fully induced by coronatine as well as by MeJA although induction by the latter was to a lesser extent and later than in the wild type. Treatment with MeOPDA, wounding and UV light, however, had hardly any effects. Tocopherol levels that showed considerable increases in the wild type after some treatments were much less affected in the mutant. However, starting levels of tocopherol were higher in non-induced dde1 than in the wild type. We conclude that jasmonate plays an important role in the signal transduction pathway regulating TAT activity and the biosynthesis of its product tocopherol.

Topics: Acetates; Arabidopsis; Cyclopentanes; Enzyme Induction; Fatty Acids, Unsaturated; Halogenated Diphenyl Ethers; Herbicides; Light; Mutation; Oxylipins; Phenyl Ethers; Phenylpyruvic Acids; Stress, Mechanical; Tocopherols; Tyrosine; Tyrosine Transaminase; Ultraviolet Rays

The Arabidopsis thaliana (L.) Heynh. mutant delayed-dehiscence2-2 (dde2-2) was identified in an En1/Spm1 transposon-induced mutant population screened for plants showing defects in fertility. The dde2-2 mutant allele is defective in the anther dehiscence process and filament elongation and thus exhibits a male-sterile phenotype. The dde2-2 phenotype can be rescued by application of methyl jasmonate, indicating that the mutant is affected in jasmonic acid biosynthesis. The combination of genetic mapping and a candidate-gene approach identified a frameshift mutation in the ALLENE OXIDE SYNTHASE (AOS) gene, encoding one of the key enzymes of jasmonic acid biosynthesis. Expression analysis and genetic complementation of the dde2-2 phenotype by overexpression of the AOS coding sequence confirmed that the male-sterile phenotype is indeed caused by the mutation in the AOS gene.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Chromosome Mapping; Chromosomes, Plant; Cyclopentanes; Fertility; Genetic Complementation Test; Intramolecular Oxidoreductases; Molecular Sequence Data; Mutation; Oxylipins; Sequence Homology, Amino Acid

Cellular stressors induce various outcomes including inhibition of cell proliferation and cell death. Sodium salicylate (SA), a plant stress hormone, can suppress the proliferation or cause apoptosis in certain mammalian cancer cells. Plant stress hormones are activators of cellular responses, including cell death, to diverse stress situations in plants. Thus, we hypothesized that plant stress hormones share the ability to adversely affect cancer cells. We found that the plant stress hormone SA suppressed proliferation of lymphoblastic leukemia, prostate, breast and melanoma human cancer cells. Jasmonic acid (JA), a plant stress hormone belonging to the Jasmonate family, induced death in lymphoblastic leukemia cells and caused suppression of cell proliferation in the other human cancer cells mentioned above. Another member of the Jasmonate family, methyl jasmonate (MJ), induced death in each of the cell lines. Plant stress hormones did not affect normal human lymphocytes, in contrast to their strong effect on lymphoblastic leukemia cells. JA and MJ caused apoptotic death, as determined by characteristic nuclear morphology, flow cytometric DNA profile and elevation of caspase-3 activity. Finally, mice bearing EL-4 lymphoma and treated with MJ, survived for significantly (P = 0.00953) longer periods of time than untreated mice. These findings suggest that plant stress hormones may potentially be a novel class of anti-cancer drugs.

Topics: Acetates; Animals; Apoptosis; Caspase 3; Caspases; Cell Cycle; Cell Division; Cyclopentanes; Dose-Response Relationship, Drug; Humans; Leukemia, T-Cell; Lymphoma; Male; Mice; Mice, Inbred C57BL; Oxylipins; Plant Growth Regulators; Tumor Cells, Cultured

In Arabidopsis, the rhizobacterial strain Pseudomonas fluorescens WCS417r triggers jasmonate (JA)- and ethylene (ET)-dependent induced systemic resistance (ISR) that is effective against different pathogens. Arabidopsis genotypes unable to express rhizobacteria-mediated ISR against the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) exhibit enhanced disease susceptibility towards this pathogen. To identify novel components controlling induced resistance, we tested 11 Arabidopsis mutants with enhanced disease susceptibility (eds) to pathogenic P. syringae bacteria for WCS417r-mediated ISR and pathogen-induced systemic acquired resistance (SAR). Mutants eds4-1, eds8-1 and eds10-1 failed to develop WCS417r-mediated ISR, while mutants eds5-1 and eds12-1 failed to express pathogen-induced SAR. Whereas eds5-1 is known to be blocked in salicylic acid (SA) biosynthesis, analysis of eds12-1 revealed that its impaired SAR response is caused by reduced sensitivity to this molecule. Analysis of the ISR-impaired eds mutants revealed that they are non-responsive to induction of resistance by methyl jasmonate (MeJA) (eds4-1, eds8-1 and eds10-1), or the ET precursor 1-aminocyclopropane-1-carboxylate (ACC) (eds4-1 and eds10-1). Moreover, eds4-1 and eds8-1 showed reduced expression of the plant defensin gene PDF1.2 after MeJA and ACC treatment, which was associated with reduced sensitivity to either ET (eds4-1) or MeJA (eds8-1). Although blocked in WCS417r-, MeJA- and ACC-induced ISR, eds10-1 behaved normally for several other responses to MeJA or ACC. The results indicate that EDS12 is required for SAR and acts downstream of SA, whereas EDS4, EDS8 and EDS10 are required for ISR acting either in JA signalling (EDS8), ET signalling (EDS4), or downstream JA and ET signalling (EDS10) in the ISR pathway.

Topics: Acetates; Amino Acids, Cyclic; Anthocyanins; Arabidopsis; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Immunity, Innate; Mutation; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Structures; Pseudomonas; Salicylic Acid; Signal Transduction

Jasmonates mediate various physiological events in plant cells such as defense responses, flowering, and senescence through intracellular and intercellular signaling pathways, and the expression of a large number of genes appears to be regulated by jasmonates. In order to obtain information on the regulatory network of jasmonate-responsive genes (JRGs) in Arabidopsis thaliana (Arabidopsis), we screened 2880 cDNA clones for jasmonate responsiveness by a cDNA macroarray procedure. Since many of the JRGs reported so far have been identified in leaf tissues, the cDNA clones used were chosen from a non-redundant EST library that was prepared from above-ground organs. Hybridization to the filters was achieved using alpha-33P-labeled single-strand DNAs synthesized from mRNAs obtained from methyl jasmonate (MeJA)-treated and untreated Arabidopsis seedlings. Data analysis identified 41 JRGs whose mRNA levels were changed by more than three fold in response to MeJA. This was confirmed by Northern blot analysis by using eight representatives. Among the 41 JRGs identified, 5 genes were JA biosynthesis genes and 3 genes were involved in other signaling pathways (ethylene, auxin, and salicylic acid). These results suggest the existence of a positive feedback regulatory system for JA biosynthesis and the possibility of crosstalk between JA signaling and other signaling pathways.

Topics: Acetates; Arabidopsis; Base Sequence; Cyclopentanes; DNA, Complementary; Feedback; Gene Expression Regulation, Plant; Genes, Plant; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Growth Regulators; RNA, Messenger; RNA, Plant; Signal Transduction

Herbivory induces both direct and indirect defenses in plants; however, some combinations of these defenses may not be compatible. The jasmonate signal cascade activated both direct (nicotine accumulations) and indirect (mono- and sesquiterpene emissions) whole-plant defense responses in the native tobacco Nicotiana attenuata Torr. Ex Wats. Nicotine accumulations were proportional to the amount of leaf wounding and the resulting increases in jasmonic acid (JA) concentrations. However, when larvae of the nicotine-tolerant herbivore, Manduca sexta, fed on plants or their oral secretions were applied to leaf punctures, the normal wound response was dramatically altered, as evidenced by large (4- to 10-fold) increases in the release of (i) volatile terpenoids and (ii) ethylene, (iii) increased (4- to 30-fold) accumulations of endogenous JA pools, but (iv) decreased or unchanged nicotine accumulations. The ethylene release, which was insensitive to inhibitors of induced JA accumulation, was sufficient to account for the attenuated nicotine response. Applications of ethylene and ethephon suppressed the induced nicotine response and pre-treatment of plants with a competitive inhibitor of ethylene receptors, 1-methylcyclopropene, restored the full nicotine response. This ethylene burst, however, did not inhibit the release of volatile terpenoids. Because parasitoids of Manduca larvae are sensitive to the dietary intake of nicotine by their hosts, this ethylene-mediated switching from direct to a putative indirect defense may represent an adaptive tailoring of a plant's defense response.

Topics: Acetates; Analysis of Variance; Animals; Cyclopentanes; Cyclopropanes; Ethylenes; Indoleacetic Acids; Manduca; Nicotiana; Nicotine; Organophosphorus Compounds; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Roots; Plants, Toxic; Salicylic Acid

Cultured cells of tobacco BY2 secrete more than 100 proteins into culture medium. Six major proteins were purified, and partial protein sequences were determined. Five of them were found to be similar to an ascorbic acid oxidase, three peroxidase isozymes and a beta-1,3-exoglucanase, respectively. A cDNA clone encoding the remaining polypeptide, whose amino acid sequence showed no similarity with earlier reported proteins, was isolated. It encoded a putative 27 kDa protein of 242 amino acids with resemblance to WCI-5, a wheat protein induced by benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) which activates genes involved in systemic acquired resistance. Transcripts of this clone accumulated upon tobacco mosaic virus infection, mechanical wounding and drought treatment, an induction profile that satisfies the definition of pathogenesis-related (PR) proteins by van Loon et al. (Plant Mol. Biol. Rep. 12 (1994) 245). No similar PR proteins have so far been reported, and therefore our newly designated NtPRp27 points to the existence of a novel PR protein family in tobacco plants.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Blotting, Northern; Cells, Cultured; Culture Media, Conditioned; Cyclopentanes; DNA, Complementary; Electrophoresis, Gel, Two-Dimensional; Electrophoresis, Polyacrylamide Gel; Gene Expression Regulation, Plant; Molecular Sequence Data; Nicotiana; Organophosphorus Compounds; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plants, Toxic; RNA, Plant; Salicylic Acid; Sequence Analysis, DNA; Sequence Analysis, Protein; Sequence Homology, Amino Acid; Tissue Distribution; Water

A cDNA clone encoding a dehydrin gene was isolated from a cDNA library prepared from white spruce (Picea glauca) needle mRNAs. The cDNA, designated PgDhn1, is 1159 nucleotides long and has an open reading frame of 735 bp with a deduced amino acid sequence of 245 residues. The PgDhn1 amino acid sequence is highly hydrophilic and possesses four conserved repeats of the characterized lysine-rich K-segment (EKKGIMD-KIKEKLPG), and an 8-serine residue stretch prior to the first lysine-rich repeat that is common to many dehydrins. The DEYGNP conserved motif is, however, absent in the PgDhn1 sequence. In unstressed plants, the highest level of transcripts was detected in stem tissue and not fully expanded vegetative buds. PgDhn1 expression was also clearly detected in reproductive buds, at various stages of development. The mRNAs corresponding to PgDhn1 cDNA were induced upon wounding and by jasmonic acid (JA) and methyl jasmonate (MeJa) treatments. Upon drought stress, increased transcript accumulation was observed in needle tissue reaching a maximum level 48 h after treatment. Treatments of seedlings with abscisic acid or ethephon also resulted in high levels of transcript accumulation in needle tissue. Finally, cold induction of PgDhn1 transcripts was also detected as early as 8 h after treatment.

Topics: Abscisic Acid; Acetates; Cold Temperature; Cyclopentanes; DNA, Complementary; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Molecular Sequence Data; Organophosphorus Compounds; Oxylipins; Plant Growth Regulators; Plant Proteins; RNA, Plant; Sequence Analysis, DNA; Stress, Mechanical; Transcription, Genetic; Trees; Water

Recent studies suggest that cross-talk between salicylic acid (SA)-, jasmonic acid (JA)-, and ethylene-dependent signaling pathways regulates plant responses to both abiotic and biotic stress factors. Earlier studies demonstrated that ozone (O(3)) exposure activates a hypersensitive response (HR)-like cell death pathway in the Arabidopsis ecotype Cvi-0. We now have confirmed the role of SA and JA signaling in influencing O(3)-induced cell death. Expression of salicylate hydroxylase (NahG) in Cvi-0 reduced O(3)-induced cell death. Methyl jasmonate (Me-JA) pretreatment of Cvi-0 decreased O(3)-induced H(2)O(2) content and SA concentrations and completely abolished O(3)-induced cell death. Cvi-0 synthesized as much JA as did Col-0 in response to O(3) exposure but exhibited much less sensitivity to exogenous Me-JA. Analyses of the responses to O(3) of the JA-signaling mutants jar1 and fad3/7/8 also demonstrated an antagonistic relationship between JA- and SA-signaling pathways in controlling the magnitude of O(3)-induced HR-like cell death.

Topics: Acetates; Arabidopsis; Cell Death; Cyclopentanes; Dose-Response Relationship, Drug; Gene Expression Regulation, Plant; Hydrogen Peroxide; Mixed Function Oxygenases; Mutation; Oxylipins; Ozone; Plant Proteins; Plants, Genetically Modified; Reactive Oxygen Species; RNA, Plant; Salicylic Acid; Signal Transduction

Pollination and fertilization trigger unique developmental programs leading to embryogenesis, ovary maturation and seed set. Pistil tissues are actively involved in pollen tube growth and respond to the presence of the growing pollen tubes by modulating the expression of specific genes. Using subtractive hybridization to isolate genes involved in pollen-pistil interactions and fertilization, we have isolated a pollination- and fertilization-induced dioxygenase which is predominantly expressed in the pistil. In situ hybridization analyses revealed that the SPP2 dioxygenase (Solanum pollinated pistil) from the self-incompatible wild potato Solanum chacoense Bitt. is also developmentally regulated, with mRNA levels gradually regressing from the tip of the style towards the ovary during pistil development. At maturity, the upper limit of SPP2 transcript distribution coincided with the abscission zone of the style and SPP2 dioxygenase expression in ovaries coincided with the fertilization receptivity period of the flower. Pollination, as well as wounding of the style, induced an increase in SPP2 mRNA steady-state levels at a distance, in the ovary. Treatments with stress hormones including methyl jasmonate, jasmonic acid and salicylic acid mimicked the wound response and also induced SPP2 transcripts in the ovary. The SPP2 dioxygenase could be involved in the biosynthesis of deterrent alkaloids in reproductive tissues or in generating chemical signals involved in pollen tube guidance.

Topics: Acetates; Amino Acid Sequence; Base Sequence; Cyclopentanes; Fertilization; Gene Expression Regulation, Plant; Gene Library; Molecular Sequence Data; Oxygenases; Oxylipins; Plant Growth Regulators; Pollen; Reproduction; RNA, Messenger; RNA, Plant; Salicylic Acid; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Solanaceae; Tissue Distribution

Jasmonic acid, methyl jasmonate, and salicylic acid have been reported to occur in plants and are thought to be essential for the regulation of systemic defense responses. This work describes a method for the quantitation in plant tissue of these regulators by reverse-phase capillary liquid chromatography interfaced to an electrospray tandem mass spectrometer. Inclusion during sample preparation of hydrogenated and/or deuterated internal standards corresponding to analogs of the regulators compensated for sample loss and permitted quantitation using the multiple reaction monitoring mode of the mass spectrometer. The free acids were analyzed in a negative-ion mode, whereas methyl jasmonate was analyzed in a positive-ion mode. Using these procedures an extract of fresh hybrid poplar leaves was found to contain per gram of leaf tissue 2.6 micrograms of jasmonic acid, 1.3 micrograms of methyl jasmonate, and 31.0 micrograms of salicylic acid. The techniques used should be applicable to other plant materials.

Topics: Acetates; Chromatography, Liquid; Cyclopentanes; Mass Spectrometry; Oxylipins; Plant Extracts; Plant Growth Regulators; Plants; Salicylates; Salicylic Acid; Sensitivity and Specificity

The coi1 mutation defines an Arabidopsis gene required for response to jasmonates, which regulate defense against insects and pathogens, wound healing, and pollen fertility. The wild-type allele, COI1, was mapped to a 90-kilobase genomic fragment and located by complementation of coi1-1 mutants. The predicted amino acid sequence of the COI1 protein contains 16 leucine-rich repeats and an F-box motif. It has similarity to the F-box proteins Arabidopsis TIR1, human Skp2, and yeast Grr1, which appear to function by targeting repressor proteins for removal by ubiquitination.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Chromosome Mapping; Cyclopentanes; Genes, Plant; Genetic Complementation Test; Molecular Sequence Data; Mutation; Open Reading Frames; Oxylipins; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Polymorphism, Genetic; Repressor Proteins; Signal Transduction; Transformation, Genetic; Ubiquitins

The role of jasmonic acid was studied in biotransformation of (--)-isopiperitenone to (--)-7-hydroxyisopiperitenone using alpha suspension cells were treated with (--)-isopiperitenone, mRNA of a cytochrome P450 was induced in a similar time-course pattern as the biotransformation shown in a previous study (Park et al., 1997). The induction of P450 mRNA and the biotransformation of (--)-isopiperitenone were increased by methyl jasmonate, but decreased by salicylhydroxamic acid, and inhibitor of jasmonic acid synthesis. These results suggest that the biotransformation involves the induction of P450 which is mediated by jasmonic acid as a signaling molecule.

Topics: Acetates; Antifungal Agents; Biotransformation; Cell Extracts; Cell Wall; Cells, Cultured; Cyclopentanes; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Gene Expression Regulation; Monoterpenes; Oxylipins; Plant Cells; Plant Growth Regulators; Plants; RNA, Messenger; Salicylamides; Terpenes; Yeasts

A protein that cross-reacts to a wheat-germ agglutinin antibody was induced in oat roots following the invasion of second-stage juveniles (J2) of the cereal cyst nematode Heterodera avenae. This protein, designated ASP45, was acid soluble, and its molecular mass was about 45 kDa on a sodium dodecyl sulfate-polyacrylamide gel. ASP45 was induced in both compatible and incompatible interactions between the nematode and the plant, and also in roots by exposure to jasmonic acid (JA) or methyl jasmonate. However, ASP45 was not induced by elicitors of pathogenesis-related proteins, abscisic acid, or wounding. Lipoxygenase activity, which is involved in JA synthesis, was higher in nematode-infected and JA-treated roots than in their noninfected, untreated counterparts. Inhibition of lipoxygenase activity in roots abolished ASP45 induction in the nematode-infected roots. Amino acid sequences similar to that of ASP45 were found in chitinases of poplar tree and Arabidopsis, even though ASP45 showed no chitinase activity. Although the biological role of ASP45 in infected roots is not clear, JA is suggested to be involved in signal transduction after pathogen invasion of the plant.

Topics: Acetates; Amino Acid Sequence; Antibody Specificity; Avena; Chitinases; Cross Reactions; Cyclopentanes; Lectins; Lipoxygenase; Molecular Sequence Data; Nematode Infections; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Lectins; Plant Proteins; Plant Roots; Sequence Analysis; Sequence Homology, Amino Acid; Wheat Germ Agglutinins