methyl-jasmonate and ethylene

One aspect of secondary metabolite production that has been studied relatively infrequently is the effect of gaseous compounds on plant cell behavior. The most influential gases are believed to be oxygen, carbon dioxide and other volatile hormones such as ethylene and methyl jasmonate. Organic compounds of interest include the promising antimalarial artemisinin (known as "qing hao su" in China where it has been a folk remedy for centuries) that is produced by Artemisia annua (sweet wormwood) and taxanes used for anticancer therapy that are produced by species of Taxus (yew). The suspension cultures of both species were grown under a variety of dissolved gas conditions in stoppered culture flasks and under conditions of continuous headspace flushing with known gas mixtures. An analysis is presented to show the culture conditions are such that equilibrium between the culture liquid and gas head-space is assured. The growth rate of the cells and their production rates of artemisinin and paclitaxel were determined. These and other parameters are correlated as functions of the gas concentrations. Interdependence of ethylene and methyl jasmonate is also explored with respect to regulation of secondary metabolite formation.

Topics: Acetates; Antimalarials; Antineoplastic Agents, Phytogenic; Artemisinins; Carbon Dioxide; Cell Culture Techniques; Cyclopentanes; Drugs, Chinese Herbal; Ethylenes; Humans; Molecular Structure; Oxygen; Oxylipins; Paclitaxel; Plant Cells; Plant Extracts; Plant Growth Regulators; Plants; Sesquiterpenes

Plants are under constant threat of infection by pathogens armed with a diverse array of effector molecules to colonize their host. Plants have, in turn, evolved sophisticated detection and response systems that decipher pathogen signals and induce appropriate defenses. Genetic analysis of plant mutants impaired in mounting a resistance response to invading pathogens has uncovered a number of distinct, but interconnecting, signaling networks that are under both positive and negative control. These pathways operate, at least partly, through the action of small signaling molecules such as salicylate, jasmonate and ethylene. The interplay of signals probably allows the plant to fine-tune defense responses in both local and systemic tissue.

Topics: Acetates; Arabidopsis; Cyclopentanes; Ethylenes; Genes, Plant; Immunity, Innate; Indoles; Oxylipins; Plant Diseases; Plant Physiological Phenomena; Plant Proteins; Plants; Protein Structure, Tertiary; Salicylic Acid; Signal Transduction; Thiazoles

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

The present work aims to evaluate the roles of methyl jasmonate (MeJA) in the formation of volatile organic compounds (VOC) from grape tomatoes during ripening. Fruits were treated with MeJA, ethylene, 1-MCP (1-methylcyclopropene), and MeJA+1-MCP, with analyses of the VOC and levels of the gene transcripts for the enzymes lipoxygenase (LOX), alcohol dehydrogenase (ADH), and hydroperoxide lyase (HPL). An intimate relationship between MeJA and ethylene in aroma formation was detected, mainly among the VOC from the carotenoid pathway. Expression of the fatty acid transcripts,

Topics: Acetates; Cyclopentanes; Ethylenes; Fruit; Gene Expression Regulation, Plant; Oxylipins; Solanum lycopersicum; Vitis; Volatile Organic Compounds

Melatonin (MT) and methyl jasmonate (MeJA) play important roles in the adaptation of plants to different stress factors by modulating stress tolerance mechanisms. The present study reports the involvement of MT (100 µM) in MeJA (10 µM)-induced photosynthetic performance and heat stress acclimation through regulation of the antioxidant metabolism and ethylene production in wheat (Triticum aestivum L.) plants. Plants exposed to 40 °C for 6 h per day for 15 days and allowed to retrieve at 28 °C showed enhanced oxidative stress and antioxidant metabolism, increased 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) activity and ethylene production, and decreased photosynthetic performance. In contrast, the exogenously applied MT and MeJA reduced oxidative stress through improved S-assimilation (+ 73.6% S content), antioxidant defense system (+ 70.9% SOD, + 115.8% APX and + 104.2% GR, and + 49.5% GSH), optimized ethylene level to 58.4% resulting in improved photosynthesis by 75%. The use of p-chlorophenyl alanine, a MT biosynthesis inhibitor along with MeJA in the presence of heat stress reduced the photosynthetic performance, ATP-S activity and GSH content, substantiated the requirement of MT in the MeJA-induced photosynthetic response of plants under heat stress. These findings suggest that MeJA evoked the plant's ability to withstand heat stress by regulating the S-assimilation, antioxidant defense system, and ethylene production, and improving photosynthetic performance was dependent on MT.

Topics: Antioxidants; Ethylenes; Heat-Shock Response; Melatonin; Oxidative Stress; Photosynthesis; Triticum

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

Many plant proteins with extracellular leucine-rich repeat (eLRR) domains play an important role in plant immunity. However, the role of one class of eLRR plant proteins-the simple eLRR proteins-in plant defenses against herbivores remains largely unknown. Here, we found that a simple eLRR protein OsI-BAK1 in rice localizes to the plasma membrane. Its expression was induced by mechanical wounding, the infestation of gravid females of brown planthopper (BPH)

Topics: Abscisic Acid; Acetates; Animals; Cyclopentanes; Ethylenes; Female; Gene Expression Regulation, Plant; Gene Silencing; Hemiptera; Leucine; Organophosphorus Compounds; Oryza; Oviposition; Oxylipins; Plant Defense Against Herbivory; Plant Immunity; Plant Proteins; Plants, Genetically Modified; Transcription Factors

Anthocyanin contributes to the coloration of pear fruit and enhances plant defenses. Members of the ethylene response factor (ERF) family play vital roles in hormone and stress signaling and are involved in anthocyanin biosynthesis. Here,

Topics: Acetates; Anthocyanins; Color; Cyclopentanes; DNA-Binding Proteins; DNA, Plant; Ethylenes; Fruit; Gene Expression Regulation, Plant; Genes, Regulator; Lanolin; Oxylipins; Plant Growth Regulators; Plant Proteins; Promoter Regions, Genetic; Pyrus; Transcriptome; Up-Regulation

Peaches are vulnerable to cold temperature, showing the symptoms of chilling injury (CI). The occurrence of CI results in irreversible aroma loss, especially 'peach-like' lactones loss during cold storage and subsequent shelf life. Methyl jasmonate (MeJA) treatment is effective in alleviating CI symptoms in peach fruit; however, its effect on peach aroma volatiles is still unknown. To explore the effect and mechanism of MeJA treatment on aroma loss of peaches, fruit was treated with 10 µmol/L MeJA, then stored at 4 °C for 3 weeks, and subsequently transferred to 20 °C to simulate shelf life for 3 days. Here, the ability of MeJA to regulate aroma lactones of 'Xiahui 6' peaches was investigated, and the expression of genes responsible for ethylene and lactones biosynthesis was considered. MeJA treatment significantly reduced internal browning index, increased ethylene production, and promoted the emission of aroma-related lactones in peaches during shelf life at room temperature. In addition, MeJA also elevated the expression of PpSAMS, PpACS3, PpACS4, PpACO, and PpACX3 during or after cold storage. These results suggested that MeJA treatment could enhance chilling tolerance in peaches and induce the recovery of ethylene and aroma lactones, which is closely related to ethylene biosynthesis as revealed by upregulated genes expression of PpSAMS, PpACS3/4, and PpACO. PRACTICAL APPLICATION: This research provides theoretical basis for the application of methyl jasmonate in fruit preservation and the basis for molecular breeding to cultivate aroma-abundant peach fruits.

Topics: Acetates; Cold Temperature; Cyclopentanes; Ethylenes; Food Storage; Fruit; Lactones; Odorants; Oxylipins; Prunus persica

A small family of ARGOS genes encodes transmembrane proteins that act as negative regulators of ethylene signaling. Recent studies show that ARGOS genes are involved in the regulation of plant growth under the influence of stress factors. However, the role of ARGOS genes in this process is poorly known. Thereby, our goal was to determine the expression profile of these genes in Arabidopsis thaliana and Nicotiana tabacum in response to phytohormone treatment and stress factors. We discovered that expression of the AtARGOS and AtARGOS-LIKE genes of A. thaliana is regulated by ethylene and depends on environmental conditions. The highest expression level of the NtARGOS-LIKE1 gene of tobacco (NtARL1) was observed in blooming flowers and young organs. It was induced by auxins, ethylene, ABA, methyl jasmonate as well as hypothermia, drought, salinity and heat stresses. To evaluate the impact of ARGOS genes on plant growth under stress, we created transgenic tobacco plants with constitutive expression of the AtARGOS-LIKE gene of A. thaliana (AtARL), controlled by a strong Dahlia mosaic virus promoter. Overexpression of the AtARL gene contributed to an increase in the volume and quantity of mesophyll cells in the leaves of tobacco under normal conditions, and also to an improvement in root growth under salinity, cold and cadmium treatment. The AtARL transgene produced a positive effect on shoot growth when exposed to drought and high salinity, and a negative effect under cold stress. Accordingly, genes of the ARGOS family can be recommended as targets for genetic engineering and genome editing in order to enhance productivity and stress tolerance of economically important plants.

Topics: Acetates; Adaptation, Physiological; Arabidopsis; Arabidopsis Proteins; Cadmium; Cold-Shock Response; Cyclopentanes; Cyclopropanes; Droughts; Ethylenes; Flowers; Gene Expression Regulation, Plant; Membrane Proteins; Nicotiana; Oxylipins; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Protein Domains; Sodium Chloride; Stress, Physiological

Topics: Acetates; Alkaloids; Anabasine; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Helix-Loop-Helix Motifs; Nicotiana; Nicotine; Oxylipins; Plant Growth Regulators; Plant Leaves; Plants, Genetically Modified; Promoter Regions, Genetic; Pyridines; Tobacco Products; Transcription Factors

Postharvest treatments such as wounding, ultrasound (US) and the exogenous application of ethylene (ET) and methyl jasmonate (MJ) have been studied as an effective tool to improve the content of secondary metabolites in fresh produce. The present study evaluated the immediate and late response (storage for 72 h at 15 °C) to US treatment (20 min, frequency 24 kHz, amplitude 100 μm) alone and combined with exogenous MJ (250 ppm) and/or ET (1000 ppm) on glucosinolates, isothiocyanates, phenolic compounds and ascorbic acid content in broccoli florets. US treatment increased the extractability of glucosinolates [glucoraphanin (795%), 4-hydroxy glucobrassicin (153%), glucobrassicin (78.6%)] and phenolics [1-sinapoyl-2-feruloylgentiobiose (57.23%)] as compared with the control (CT). The combined application of MJ and US in broccoli florets, induced a synergistic effect on the accumulation of 4-hydroxy glucobrassicin (187.1%), glucoerucin (111.92%), gluconasturtiin (755.9%), neoglucobrassicin (232.8%), 3-O-caffeoylquinic acid (73.4%), 1-sinapoyl-2-ferulolylgentiobiose (56.0%), and 1,2,2-trisinapoylgentiobiose (136.7%) at 72 h of storage. Interestingly, when the three stressors were applied together the synergistic effect of US + MJ observed on the accumulation of glucosinolates and phenolics was repressed. In general, the ascorbic acid content was not affected by US treatment and decreased in most samples during storage. However, when MJ + ET were applied, the content of total ascorbic acid was significantly reduced in CT + MJ + ET and US + MJ + ET samples after 72 h of storage by 53.4% and 86.6%, respectively, as compared with CT 0 h samples. Based on the results herein obtained, the application of US can be an effective tool to enhance the extractability of certain glucocosinolate and phenolic compounds in broccoli. Moreover, due to the synergistic effect observed on the accumulation of bioactive compounds, the combined application of US and MJ could be a practical approach to yield higher levels of glucosinolates and phenolic compounds in broccoli during storage.

Topics: Acetates; Brassica; Chromatography, High Pressure Liquid; Cyclopentanes; Dietary Supplements; Ethylenes; Flowers; Food Preservation; Glucosinolates; Oxylipins; Phenols; Plant Growth Regulators; Ultrasonic Waves

The corn leaf aphid (CLA;

Topics: Acetates; Animals; Aphids; Benzoxazines; Cyclopentanes; Ethylenes; Fatty Acids, Unsaturated; Fertility; Glucans; Herbivory; Oxylipins; Phloem; Zea mays

Jasmonic acid (JA)- and ethylene-mediated signaling pathways are reported to have synergistic effects on inhibiting gray mold. The present study aimed to explain the role of ethylene perception in methyl jasmonate (MeJA)-mediated immune responses. Results showed that exogenous MeJA enhanced disease resistance, accompanied by the induction of endogenous JA biosynthesis and ethylene production, which led to the activation of the phenolic metabolism pathway. Blocking ethylene perception using 1-methylcyclopropene (1-MCP) either before or after MeJA treatment could differently weaken the disease responses induced by MeJA, including suppressing the induction of ethylene production and JA contents and reducing activities of lipoxygenase and allene oxide synthase compared to MeJA treatment alone. Consequently, MeJA-induced elevations in the total phenolic content and the activities of phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, 4-coumarate:coenzyme A ligase, and peroxidase were impaired by 1-MCP. These results suggested that ethylene perception participated in MeJA-mediated immune responses in tomato fruit.

Topics: Acetates; Botrytis; Cyclopentanes; Disease Resistance; Ethylenes; Fruit; Gene Expression Regulation, Plant; Oxylipins; Phenylalanine Ammonia-Lyase; Plant Diseases; Plant Growth Regulators; Plant Proteins; Solanum lycopersicum; Trans-Cinnamate 4-Monooxygenase

Signal crosstalk between jasmonate and ethylene is crucial for a proper maintenance of defense responses and development. Although previous studies reported that both jasmonate and ethylene also function as modulators of stomatal movements, the signal crosstalk mechanism in stomatal guard cells remains unclear. Here, we show that the ethylene signaling inhibits jasmonate signaling as well as abscisic acid (ABA) signaling in guard cells of Arabidopsis thaliana and reveal the signaling crosstalk mechanism. Both an ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and an ethylene-releasing compound ethephon induced transient stomatal closure, and also inhibited methyl jasmonate (MeJA)-induced stomatal closure as well as ABA-induced stomatal closure. The ethylene inhibition of MeJA-induced stomatal closure was abolished in the ethylene-insensitive mutant etr1-1, whereas MeJA-induced stomatal closure was impaired in the ethylene-overproducing mutant eto1-1. Pretreatment with ACC inhibited MeJA-induced reactive oxygen species (ROS) production as well as ABA-induced ROS production in guard cells but did not suppress ABA activation of OPEN STOMATA 1 (OST1) kinase in guard cell-enriched epidermal peels. The whole-cell patch-clamp analysis revealed that ACC attenuated MeJA and ABA activation of S-type anion channels in guard cell protoplasts. However, MeJA and ABA inhibitions of Kin channels were not affected by ACC pretreatment. These results suggest that ethylene signaling inhibits MeJA signaling and ABA signaling by targeting S-type anion channels and ROS but not OST1 kinase and K+ channels in Arabidopsis guard cells.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Ethylenes; Ion Channels; Oxylipins; Plant Growth Regulators; Plant Stomata; Protein Kinases; Reactive Oxygen Species; Signal Transduction

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

The medicinal plant Catharanthus roseus accumulates large numbers of terpenoid indole alkaloids (TIAs), including the pharmaceutically important vinblastine, vincristine, ajmalicine, and serpentine. The phytohormone ethylene or methyl jasmonate (MeJA) can markedly enhance alkaloid accumulation. The interaction between ethylene or MeJA in the regulation of TIA biosynthesis in C. roseus is unknown. Here, a metabolomics platform is reported that is based on liquid chromatography (LC) coupled with time-of-flight mass spectrometry to study candidate components for TIA biosynthesis, which is controlled by ethylene or MeJA in C. roseus. Multivariate analysis identified 16 potential metabolites mostly associated with TIA metabolic pathways and seven targeted metabolites, outlining the TIA biosynthesis metabolic networks controlled by ethylene or MeJA. Interestingly, ethylene and MeJA regulate the 2-C-methyl-d-erythritol 4-phosphate (MEP) and acetate-mevalonate (MVA) pathways through AACT and HMGS and through DXS, respectively, to induce TIA biosynthesis in C. roseus. Overall, both nontargeted and targeted metabolomics, as well as transcript analysis, were used to reveal that MeJA and ethylene control different metabolic networks to induce TIA biosynthesis.

Topics: Acetates; Catharanthus; Chromatography, Liquid; Cyclopentanes; Ethylenes; Mass Spectrometry; Metabolic Networks and Pathways; Metabolomics; Mevalonic Acid; Oxylipins; Secologanin Tryptamine Alkaloids; Vinblastine; Vincristine

OsEXPA10 gene coordinates the balance between rice development and biotic resistance. Expansins are proteins that can loosen the cell wall. Previous studies have indicated that expansin-encoding genes were involved in defense against abiotic stress, but little is known about the involvement of expansins in biotic stress. Brown planthopper (BPH) is one of the worst insect pests of rice in the Asia-Pacific planting area, and many efforts have been made to identify and clone BPH-resistance genes for use in breeding resistant cultivars. At the same time, rice blast caused by Magnaporthe grisea is one of the three major diseases that severely affect rice production worldwide. Here, we demonstrated that one rice expansin-encoding gene, OsEXPA10, functions in both rice growth and biotic resistance. Over expression of OsEXPA10 improved rice growth but also increased susceptibility to BPH infestation and blast attack, while knock-down OsEXPA10 gene expression resulted in reduced plant height and grain size, but also increased resistance to BPH and the blast pathogen. These results imply that OsEXPA10 mediates the balance between rice development and biotic resistance.

Topics: Acetates; Animals; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Hemiptera; Herbivory; Magnaporthe; Oryza; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Salicylic Acid; Seeds; Stress, Physiological

Transcriptomic analysis indicates that the bacterial signalling molecule lumichrome enhances plant growth through a combination of enhanced cell division and cell enlargement, and possibly enhances photosynthesis. Lumichrome (7,8 dimethylalloxazine), a novel multitrophic signal molecule produced by Sinorhizobium meliloti bacteria, has previously been shown to elicit growth promotion in different plant species (Phillips et al. in Proc Natl Acad Sci USA 96:12275-12280, https://doi.org/10.1073/pnas.96.22.12275 , 1999). However, the molecular mechanisms that underlie this plant growth promotion remain obscure. Global transcript profiling using RNA-seq suggests that lumichrome enhances growth by inducing genes impacting on turgor driven growth and mitotic cell cycle that ensures the integration of cell division and expansion of developing leaves. The abundance of XTH9 and XPA4 transcripts was attributed to improved mediation of cell-wall loosening to allow turgor-driven cell enlargement. Mitotic CYCD3.3, CYCA1.1, SP1L3, RSW7 and PDF1 transcripts were increased in lumichrome-treated Arabidopsis thaliana plants, suggesting enhanced growth was underpinned by increased cell differentiation and expansion with a consequential increase in biomass. Synergistic ethylene-auxin cross-talk was also observed through reciprocal over-expression of ACO1 and SAUR54, in which ethylene activates the auxin signalling pathway and regulates Arabidopsis growth by both stimulating auxin biosynthesis and modulating the auxin transport machinery to the leaves. Decreased transcription of jasmonate biosynthesis and responsive-related transcripts (LOX2; LOX3; LOX6; JAL34; JR1) might contribute towards suppression of the negative effects of methyl jasmonate (MeJa) such as chlorophyll loss and decreases in RuBisCO and photosynthesis. This work contributes towards a deeper understanding of how lumichrome enhances plant growth and development.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Bacterial Proteins; Biomass; Cell Division; Cell Enlargement; Cell Wall; Chlorophyll; Cyclopentanes; Ethylenes; Flavins; Gene Expression Profiling; Indoleacetic Acids; Oxylipins; Plant Growth Regulators; Plant Leaves; Signal Transduction; Sinorhizobium meliloti

Ethylene is an important plant hormone that controls many physiological processes in plants. Conventional methods for detecting ethylene include gas chromatographs or optical mid-infrared sensors, which are expensive and, in the case of gas chromatographs, are hardly suitable for automated parallelized online measurement. Electrochemical ethylene sensors are cheap but often suffer from poor resolution, baseline drifting, and target gas oxidation. Thus, measuring ethylene at extremely low levels is challenging.. This report demonstrates the integration of electrochemical ethylene sensors into a respiration activity monitoring system (RAMOS) that measures, in addition to the oxygen transfer rate, the ethylene transfer rate in eight parallel shake flasks. A calibration method is presented that is not prone to baseline drifting and considers target gas oxidation at the sensor. In this way, changes in ethylene transfer rate as low as 4 nmol/L/h can be resolved. In confirmatory experiments, the overall accuracy of the method was similar to that of gas chromatography-mass spectrometry (GC/MS) measurements. The RAMOS-based ethylene determination method was exemplified with parsley suspension-cultured cells that were primed for enhanced defense by pretreatment with salicylic acid, methyl jasmonate or 4-chlorosalicylic acid and challenged with the microbial pattern Pep13. Ethylene release into the headspace of the shake flask was observed upon treatment with salicylic acid and methyl jasmonate was further enhanced, in case of salicylic acid and 4-chlorosalicylic acid, upon Pep13 challenge.. A conventional RAMOS device was modified for simultaneous measurement of the ethylene transfer rate in eight parallel shake flasks at nmol/L/h resolution. For the first time electrochemical sensors are used to provide a medium-throughput method for monitoring ethylene release by plants. Currently, this can only be achieved by costly laser-based detection systems and automated gas chromatographs. The new method is particularly suitable for plant cell suspension cultures. However, the method may also be applicable to intact plants, detached leaves or other plant tissues. In addition, the general principle of the technology is likely extendable to other volatiles or gases as well, such as nitric oxide or hydrogen peroxide.

Topics: Acetates; Calibration; Cells, Cultured; Cyclopentanes; Ethylenes; Online Systems; Oxidation-Reduction; Oxygen; Oxylipins; Petroselinum; Plant Growth Regulators; Salicylates

The medicinal plant, Catharanthus roseus (C. roseus), accumulates a wide range of terpenoid indole alkaloids (TIAs). Ethylene (ET) and methyl-jasmonate (MeJA) were previously reported as effective elicitors for the production of various valuable secondary metabolites of C. roseus, while a few ET or MeJA induced transcriptomic research is yet reported on this species. In this study, the de-novo transcriptome assembly of C. roseus is performed by using the next-generation sequencing technology.. The result shows that phenolic biosynthesis genes respond specifically to ET in leaves, monoterpenoid biosynthesis genes respond specifically to MeJA in roots. By screening the database, 23 ATP-binding cassette (ABC) transporter partial sequences are identified in C. roseus. On this basis, more than 80 key genes that encode key enzymes (namely TIA pathway, transcriptional factor (TF) and candidate ABC transporter) of alkaloid synthesis in TIA biosynthetic pathways are chosen to explore the integrative responses to ET and MeJA at the transcriptional level. Our data indicated that TIA accumulation is strictly regulated by the TF ethylene responsive factor (ERF) and bHLH iridoid synthesis 1 (BIS1). The heatmap, combined with principal component analysis (PCA) of C. roseus, shows that ERF co-expression with ABC2 and ABC8 specific expression in roots affect the root-specific accumulation of vinblastine in C. roseus. On the contrast, BIS1 activities follow a similar pattern of ABC3 and CrTPT2 specific expression in leaves, which affects the leaf-specific accumulation of vindoline in C. roseus.. Results presented above illustrate that ethylene has a stronger effect than MeJA on TIA induction at both transcriptional and metabolite level. Furthermore, meta-analysis reveals that ERF and BIS1 form a positive feedback loop connecting two ABC transporters respectively and are actively involved in TIAs responding to ET and MeJA in C. roseus.

Topics: Acetates; ATP-Binding Cassette Transporters; Biosynthetic Pathways; Catharanthus; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Oxylipins; Plant Leaves; Plant Proteins; Plant Roots; Principal Component Analysis; Secologanin Tryptamine Alkaloids; Transcriptome

Topics: Acetates; Cyclopentanes; Ethylenes; Gene Expression Profiling; High-Throughput Nucleotide Sequencing; Metabolic Networks and Pathways; Oxylipins; Plant Growth Regulators; Polyamines; Reproduction; Rhodophyta; Seaweed; Transcriptome

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating disease of wheat (Triticum aestivum) worldwide. Wheat high-temperature seedling plant (HTSP) resistance to Pst is non-race-specific and durable. WRKY transcription factors have been proven to play important roles in plant defence responses to attacks by several pathogens. However, there is no direct evidence as to whether WRKY transcription factors play a role in HTSP resistance to Pst. We isolated a WRKY gene, named TaWRKY70, from wheat cultivar Xiaoyan 6. The expression level of TaWRKY70 was increased significantly when exposed to high temperatures (HTs) during the initial symptom expression stage of Pst infection. The expression of this gene increased in plants treated with ethylene (ET), salicylic acid (SA) and cold (4°C) stresses, but decreased in plants treated with methyl jasmonate (MeJA) and heat (40°C) stresses. Silencing of TaWRKY70 led to greater susceptibility to Pst (in terms of the increase in length of uredinial pustules and the decrease in the number of necrotic cells) compared with non-silenced plants when exposed to HT during the initial symptom expression stage of Pst infection, coinciding with expression changes of the ET- and SA-responsive genes TaPIE1 and TaPR1.1. In contrast, the expression level of the jasmonic acid (JA)-responsive gene TaAOS was not affected by TaWRKY70. These results indicate that TaWRKY70 is positively involved in HTSP resistance, during which SA and ET signalling are probably activated.

Topics: Acetates; Basidiomycota; Cold Temperature; Cyclopentanes; Ethylenes; Hot Temperature; Oxylipins; Plant Diseases; Plant Proteins; Salicylic Acid; Seedlings; Transcription Factors; Triticum

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

Stomatal closure is affected by various stimuli such as light, atmospheric carbon dioxide concentration, humidity and phytohormones. Our research focuses on phytohormones, specifically: abscisic acid (ABA), ethylene (ET) and methyl jasmonate (MeJA) that are responsible for the regulation of several plant processes, especially in guard cell signalling. While several studies show that these three phytohormones cause stomatal closure in plants, only two studies are notable for establishing a mathematical model of guard cell signalling involving phytohormones. Those two studies employed Boolean modelling and mechanistic ordinary differential equations modelling. In this study, we propose a new mathematical model of guard cell transduction network for stomatal closure using continuous logical modelling framework. Results showed how the different components of the network function. Furthermore, the model verified the role of antioxidants in the closure mechanism, and the diminished closure level of stomata with combined ABA-ET stimulus. The analysis was extended to ABA-ET-MeJA crosstalk.

Topics: Abscisic Acid; Acetates; Cyclopentanes; Ethylenes; Models, Theoretical; Oxylipins; Plant Growth Regulators; Plant Stomata

To gain a better understanding of the regulatory mechanism(s) modulating expression of the ornithine decarboxylase gene ODC during cystocarp development in the red seaweed Grateloupia imbricata, DNA motifs found in the 5'-upstream region of the gene were identified by in silico analysis. In addition, when infertile G. imbricata thalli were treated with ethylene, methyl jasmonate, or light as an elicitor of cystocarp development, different ODC expression patterns were observed. ODC expression correlated with (i) the elicitation (treatment) period and the period post-treatment just prior to observation of the first visible developing cystocarps (disclosure period), and (ii) the type of elicitor. Ethylene and light activated ODC expression during the elicitation period, and methyl jasmonate activated its expression during the disclosure period, suggesting that initiation and cystocarp development may involve more than one signaling pathway. In addition, expression of ODC was 450-fold greater when thalli were stimulated by ethylene compared with untreated control thalli, suggesting that G. imbricata mounts an efficient response to sense and activate ethylene-responsive signaling pathways. The patterns of differential ODC expression induced by the different elicitors during cystocarp development might provide an useful tool for characterizing the precise transcriptional regulation of ODC in G. imbricata.

Topics: Acetates; Base Sequence; Chromosome Mapping; Cyclopentanes; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Nucleotide Motifs; Ornithine Decarboxylase; Oxylipins; Photoperiod; Plant Growth Regulators; Rhodophyta; Sequence Analysis, DNA

Metacaspases, a family of cysteine proteases, have been suggested to play important roles in programmed cell death (PCD) during plant development and stress responses. To date, no systematic characterization of this gene family has been reported in rubber tree (Hevea brasiliensis). In the present study, nine metacaspase genes, designated as HbMC1 to HbMC9, were identified from whole-genome sequence of rubber tree. Multiple sequence alignment and phylogenetic analyses suggested that these genes were divided into two types: type I (HbMC1-HBMC7) and type II (HbMC8 and HbMC9). Gene structure analysis demonstrated that type I and type II HbMCs separately contained four and two introns, indicating the conserved exon-intron organization of HbMCs. Quantitative real-time PCR analysis revealed that HbMCs showed distinct expression patterns in different tissues, suggesting the functional diversity of HbMCs in various tissues during development. Most of the HbMCs were regulated by drought, cold, and salt stress, implying their possible functions in regulating abiotic stress-induced cell death. Of the nine HbMCs, HbMC1, HbMC2, HbMC5, and HbMC8 displayed a significantly higher relative transcript accumulation in barks of tapping panel dryness (TPD) trees compared with healthy trees. In addition, the four genes were up-regulated by ethephon (ET) and methyl jasmonate (MeJA), indicating their potential involvement in TPD resulting from ET- or JA-induced PCD. In summary, this work provides valuable information for further functional characterization of HbMC genes in rubber tree.

Topics: Acetates; Amino Acid Sequence; Caspases; Cold Temperature; Cyclopentanes; Droughts; Ethylenes; Exons; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant; Hevea; Introns; Latex; Multigene Family; Oxylipins; Phylogeny; Plant Bark; Plant Proteins; Protein Domains; Sequence Alignment; Stress, Physiological

A 2000-bp 5'-flanking region of VvPAL-like was isolated from 'Summer Black' grapevine by PCR amplification, named pVvPAL-like. To gain a better understanding of the expression and regulatory mechanism of VvPAL-like, a chimeric expression unit consisting of the β-glucuronidase (GUS) reporter gene under the control of a 2000-bp fragment of the VvPAL-like promoter was transformed into tobacco via Agrobacterium tumefaciens. Histochemical staining showed that the full-length promoter directs efficient expression of the reporter gene in cotyledons and hypocotyls, stigma, style, anthers, pollen, ovary, trichomes, and vascular bundles of transgenic plants. A series of 5' progressive deletions of the promoter revealed the presence of a negative regulatory region (-424 to -292) in the VvPAL-like promoter. Exposure of the transgenic tobacco plants to various abiotic stresses demonstrated that the full-length construct could be induced by light, copper (Cu), abscisic acid (ABA), indole-3-acetic (IAA), methyl jasmonate (MeJA) (N-1-naphthylphthalamic acid), ethylene, and drought. Furthermore, the ethylene-responsive region was found to be located in the -1461/-930 fragment, while the element(s) for the MeJA-responsive expression may be present in the -424/-292 region in the VvPAL-like promoter. These findings will help us to better understand the molecular mechanisms by which VvPAL-like participates in biosynthesis of flavonoids and stress responses.

Topics: Abscisic Acid; Acetates; Agrobacterium tumefaciens; Copper; Cyclopentanes; Droughts; Ethylenes; Gene Expression Regulation, Plant; Genes, Reporter; Glucuronidase; Light; Nicotiana; Oxylipins; Phthalimides; Plants, Genetically Modified; Promoter Regions, Genetic; Transcriptome; Vitis

The effects of pre-harvest methyl jasmonate (MJ) treatments on ethylene production, respiration rate, bioactive compounds and physico-chemical parameters of plum fruits (Prunus salicina Lindell cv. 'Fortune' and 'Friar') were investigated. Whole trees were sprayed once with an aqueous solution containing MJ (0, 1120 and 2240 mg L(-1)) 2 weeks before the anticipated commercial harvest for each cultivar.. In both plum cultivars, 1120 mg L(-1) MJ significantly increased hue angle of fruits. The fruit mass and geometric mean diameter were lower in MJ treatments while flesh firmness was higher, except at initial harvest date. Soluble solids concentration increased and titratable acidity decreased with MJ treatments. MJ-treated fruits exhibited higher levels of ethylene production and respiration rate. MJ was more effective in increasing water-soluble antioxidant activity, water-soluble phenolics and individual phenolics. Chlorogenic acid, caffeic acid, rutin, ferulic acid, naringenin and kaempferol contents significantly increased with 2240 mg L(-1) MJ.. This study revealed that pre-harvest MJ treatments were effective in delaying softening of late-harvested fruits and increasing bioactive compounds of plum fruits.

Topics: Acetates; Chlorogenic Acid; Cyclopentanes; Ethylenes; Flavonoids; Fruit; Humans; Oxylipins; Phenols; Plant Growth Regulators; Prunus

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

A pepper bZIP transcription factor gene, CabZIP2, was isolated from pepper leaves infected with a virulent strain of Xanthomonas campestris pv. vesicatoria. Transient expression analysis of the CabZIP2-GFP fusion protein in Nicotiana benthamiana revealed that the CabZIP2 protein is localized in the cytoplasm as well as the nucleus. The acidic domain in the N-terminal region of CabZIP2 that is fused to the GAL4 DNA-binding domain is required to activate the transcription of reporter genes in yeast. Transcription of CabZIP2 is induced in pepper plants inoculated with virulent or avirulent strains of X. campestris pv. vesicatoria. The CabZIP2 gene is also induced by defense-related hormones such as salicylic acid, methyl jasmonate, and ethylene. To elucidate the in vivo function of the CabZIP2 gene in plant defense, virus-induced gene silencing in pepper and overexpression in Arabidopsis were used. CabZIP2-silenced pepper plants were susceptible to infection by the virulent strain of X. campestris pv. vesicatoria, which was accompanied by reduced expression of defense-related genes such as CaBPR1 and CaAMP1. CabZIP2 overexpression in transgenic Arabidopsis plants conferred enhanced resistance to Pseudomonas syringae pv. tomato DC3000. Together, these results suggest that CabZIP2 is involved in bacterial disease resistance.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Basic-Leucine Zipper Transcription Factors; Capsicum; Cyclopentanes; Cytoplasm; Disease Resistance; Ethylenes; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Pseudomonas syringae; Sequence Homology, Amino Acid; Transcription Factors; Xanthomonas campestris

The HbCZF1 protein binds to the hmg1 promoter in yeast and this interaction was confirmed in vitro. The hmg1 promoter was activated in transgenic plants by HbCZF1. Biosynthesis of natural rubber is known to be based on the mevalonate pathway in Hevea brasiliensis. The final step in the mevalonate production is catalyzed by the branch point enzyme, 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGR), which shunts HMG-CoA into the isoprenoid pathway, leading to the synthesis of natural rubber. However, molecular regulation of HMGR expression is not known. To study the transcriptional regulation of HMGR, the yeast one-hybrid experiment was performed to screen the latex cDNA library using the hmg1 (one of the three HMGR in H. brasiliensis) promoter as bait. One cDNA that encodes the CCCH-type zinc finger protein, designated as HbCZF1, was isolated from H. brasiliensis. HbCZF1 interacted with the hmg1 promoter in yeast one-hybrid system and in vitro. HbCZF1 contains a 1110 bp open reading frame that encodes 369 amino acids. The deduced HbCZF1 protein was predicted to possess a typical C-X7-C-X5-C3-H CCCH motif and RNA recognition motif. HbCZF1 was predominant in the latex, but little expression was detected in the leaves, barks, and roots. Furthermore, in transgenic tobacco plants, over-expression of HbCZF1 highly activated the hmg1 promoter. These results suggested that HbCZF1 may participate in the regulation of natural rubber biosynthesis in H. brasiliensis.

Topics: Acetates; Amino Acid Sequence; Cell Nucleus; Cyclopentanes; Electrophoretic Mobility Shift Assay; Ethylenes; Gene Expression Regulation, Plant; Hevea; Hydroxymethylglutaryl CoA Reductases; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Protein Binding; Saccharomyces cerevisiae; Subcellular Fractions; Transcription, Genetic; Zinc Fingers

Jasmonates (JAs) play important roles in gummosis in peach. Mechanical damage, methyl jasmonate (MeJa), and ethylene can induce gummosis on peach shoots in the field. In this study, we used MeJa (2%, w/w) to induce gummosis on current-year shoots in peach on high temperature (35°C). Based on the experimental model, we studied the influence of factors on the development of peach gummosis. Our experimental results showed that high temperature could promote gummosis development induced by MeJa. Exogenous CaCl2 treatment reduced the degree of gummosis by increasing the calcium content in shoots, which is conducive to the synthesis and maintenance of the cell wall. Using digital gene expression (DGE), 3831 differentially expressed genes were identified in the MeJa treatment versus the control. By analyzing changes in gene expression associated with cell wall degradation, genes encoding pectin methylesterase (PME) and endo-polygalacturonase (PG) were found to be significantly induced, suggesting that they are key enzymes in cell wall degradation that occurs during MeJa-induced gummosis. Genes for glycosyltransferase (GT) and cellulose synthase (CS) were also significantly upregulated by MeJa. This result suggests that MeJa treatment not only promotes the degradation of polysaccharides to destroy the cell wall, but also promotes the synthesis of new polysaccharides. We also analyzed changes in gene expression associated with sugar metabolism, senescence, and defense. MeJa treatment affected the expression of genes related to sugar metabolism and promoted plant senescence. Among the defense genes, the expression pattern of phenylalanine ammonium lyase (PAL) suggested that PAL may play an important role in protecting against the effects of MeJa treatment. Our experimental results showed that MeJa treatment can promote the biosynthesis and signal transduction of ethylene in peach shoots; they can induce gummosis on peach shoots respectively, and there are overlaps between the molecular mechanisms of gummosis induced by them, the intersection point between them remains unclear.

Topics: Acetates; Calcium; Calcium Chloride; Cell Wall; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Oxylipins; Plant Shoots; Polysaccharides; Prunus persica; Signal Transduction; Stress, Physiological; Temperature

Over the last two decades, many carotenogenic genes have been cloned and used to generate metabolically engineered plants producing higher levels of carotenoids. However, comparatively little is known about the regulation of endogenous carotenogenic genes in higher plants, and this restricts our ability to predict how engineered plants will perform in terms of carotenoid content and composition. During petal development in the Great Yellow Gentian (Gentiana lutea), carotenoid accumulation, the formation of chromoplasts and the upregulation of several carotenogenic genes are temporally coordinated. We investigated the regulatory mechanisms responsible for this coordinated expression by isolating five G. lutea carotenogenic gene (GlPDS, GlZDS, GlLYCB, GlBCH and GlLYCE) promoters by inverse polymerase chain reaction (PCR). Each promoter was sufficient for developmentally regulated expression of the gusA reporter gene following transient expression in tomato (Solanum lycopersicum cv. Micro-Tom). Interestingly, the GlLYCB and GlBCH promoters drove high levels of gusA expression in chromoplast-containing mature green fruits, but low levels in chloroplast-containing immature green fruits, indicating a strict correlation between promoter activity, tomato fruit development and chromoplast differentiation. As well as core promoter elements such as TATA and CAAT boxes, all five promoters together with previously characterized GlZEP promoter contained three common cis-regulatory motifs involved in the response to methyl jasmonate (CGTCA) and ethylene (ATCTA), and required for endosperm expression (Skn-1_motif, GTCAT). These shared common cis-acting elements may represent binding sites for transcription factors responsible for co-regulation. Our data provide insight into the regulatory basis of the coordinated upregulation of carotenogenic gene expression during flower development in G. lutea.

Topics: Acetates; Base Sequence; Carotenoids; Chloroplasts; Cloning, Molecular; Cyclopentanes; Ethylenes; Fruit; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Gentiana; Glucuronidase; Molecular Sequence Data; Oxylipins; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Plastids; Polymerase Chain Reaction; Promoter Regions, Genetic; Response Elements; Solanum lycopersicum; Up-Regulation

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

MYB transcription factors are a large family of proteins involved in the regulation of secondary metabolism and cell shape, the enhancement of disease resistance and the response to different stresses. In this study, the role of TaMYB4 in wheat against biotic and abiotic stresses was investigated. TaMYB4 was cloned from wheat cv. Suwan11 [the leaves were infected with Puccinia striiformis f.sp. tritici (Pst)]; the TaMYB4 protein is 243 amino acids in length. In addition, TaMYB4 exhibited high similarity with BdMYB4 from Brachypodium distachyon, which was also identified as a member of the R2R3-MYB family of genes. Furthermore, transient expression analysis showed that the deduced TaMYB4 protein was localised in the nucleus of onion epidermal cells. Additionally, a yeast one-hybrid assay revealed that TaMYB4 exhibits transcriptional activity and the C-terminus is necessary for the activation of transcription. The transcript levels of TaMYB4 were observed directly and were found to be significantly upregulated in the early stage and 48 h after inoculation with the incompatible Pst. The transcripts of TaMYB4 were detected in the wheat roots, culms and leaves. Moreover, the transcription of TaMYB4 was induced by salicylic acid, ethylene, abscisic acid and methyl jasmonate hormones. The same results were obtained with cold and wound treatments. Furthermore, the knockdown of TaMYB4 expression using virus-induced gene silencing enhanced the susceptibility of wheat cultivar Suwon11 to the incompatible race of Pst. These results demonstrate that TaMYB4 plays a role in the wheat response to biotic stress.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Basidiomycota; Cold Temperature; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Knockdown Techniques; Molecular Sequence Data; Oxylipins; Phylogeny; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plant Viruses; Reverse Transcriptase Polymerase Chain Reaction; Salicylic Acid; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; Stress, Mechanical; Transcription Factors; Triticum

Leaf-to-leaf systemic immune signaling known as systemic acquired resistance is poorly understood in monocotyledonous plants. Here, we characterize systemic immunity in barley (Hordeum vulgare) triggered after primary leaf infection with either Pseudomonas syringae pathovar japonica (Psj) or Xanthomonas translucens pathovar cerealis (Xtc). Both pathogens induced resistance in systemic, uninfected leaves against a subsequent challenge infection with Xtc. In contrast to systemic acquired resistance in Arabidopsis (Arabidopsis thaliana), systemic immunity in barley was not associated with NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 or the local or systemic accumulation of salicylic acid. Instead, we documented a moderate local but not systemic induction of abscisic acid after infection of leaves with Psj. In contrast to salicylic acid or its functional analog benzothiadiazole, local applications of the jasmonic acid methyl ester or abscisic acid triggered systemic immunity to Xtc. RNA sequencing analysis of local and systemic transcript accumulation revealed unique gene expression changes in response to both Psj and Xtc and a clear separation of local from systemic responses. The systemic response appeared relatively modest, and quantitative reverse transcription-polymerase chain reaction associated systemic immunity with the local and systemic induction of two WRKY and two ETHYLENE RESPONSIVE FACTOR (ERF)-like transcription factors. Systemic immunity against Xtc was further associated with transcriptional changes after a secondary/systemic Xtc challenge infection; these changes were dependent on the primary treatment. Taken together, bacteria-induced systemic immunity in barley may be mediated in part by WRKY and ERF-like transcription factors, possibly facilitating transcriptional reprogramming to potentiate immunity.

Topics: Abscisic Acid; Acetates; Cyclopentanes; Ethylenes; Hordeum; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Leaves; Pseudomonas syringae; Salicylic Acid; Thiadiazoles; Xanthomonas

Methyl jasmonate (MeJA) treatment can significantly increase glucosinolate (GS) concentrations in Brassica vegetables and potentially enhance anticancer bioactivity. Although MeJA treatment may promote ethylene biosynthesis, which can be detrimental to postharvest quality, there are no previous reports of its effect on cauliflower postharvest quality. To address this, cauliflower curds in field plots were sprayed with either 0.1 % Triton X-100 (control) or 500 μM MeJA solutions four days prior to harvest, then stored at 4 °C. Tissue subsamples were collected after 0, 10, 20, and 30 days of postharvest storage and assayed for visual color change, ethylene production, GS concentrations, and extract quinone reductase inductive activity. MeJA treatment increased curd GS concentrations of glucoraphanin, glucobrassicin, and neoglucobrassicin by 1.5, 2.4, and 4.6-fold over controls, respectively. MeJA treated cauliflower showed significantly higher quinone reductase activity, a biomarker for anticancer bioactivity, without reducing visual color and postharvest quality for 10 days at 4 °C storage.

Topics: Acetates; Anticarcinogenic Agents; Brassica; Color; Cyclopentanes; Ethylenes; Food Handling; Food Quality; Glucosinolates; Imidoesters; Indoles; NAD(P)H Dehydrogenase (Quinone); Octoxynol; Oximes; Oxylipins; Plant Extracts; Sulfoxides

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

Global transcriptome analysis revealed common regulons for biotic/abiotic stresses, and some of these regulons encoding signaling components in both stresses were newly identified in this study. In this study, we aimed to identify plant responses to multiple stress conditions and discover the common regulons activated under a variety of stress conditions. Global transcriptome analysis revealed that salicylic acid (SA) may affect the activation of abiotic stress-responsive genes in pepper. Our data indicate that methyl jasmonate (MeJA) and ethylene (ET)-responsive genes were primarily activated by biotic stress, while abscisic acid (ABA)-responsive genes were activated under both types of stresses. We also identified differentially expressed gene (DEG) responses to specific stress conditions. Biotic stress induces more DEGs than those induced by abiotic and hormone applications. The clustering analysis using DEGs indicates that there are common regulons for biotic or abiotic stress conditions. Although SA and MeJA have an antagonistic effect on gene expression levels, SA and MeJA show a largely common regulation as compared to the regulation at the DEG expression level induced by other hormones. We also monitored the expression profiles of DEG encoding signaling components. Twenty-two percent of these were commonly expressed in both stress conditions. The importance of this study is that several genes commonly regulated by both stress conditions may have future applications for creating broadly stress-tolerant pepper plants. This study revealed that there are complex regulons in pepper plant to both biotic and abiotic stress conditions.

Topics: Abscisic Acid; Acetates; Capsicum; Cluster Analysis; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Growth Regulators; Regulon; Salicylic Acid; Stress, Physiological; Transcriptome

To investigate the role of jasmonates (JAs) in the ripening of Fragaria chiloensis fruit, two concentrations of methyl jasmonate (MeJA, 10 and 100 μM) were evaluated at 2, 5 and 9 d using an in vitro ripening system. Fruit quality parameters; the contents of anthocyanin, lignin and cell wall polymers; and the transcriptional profiles of several ripening-related genes were analyzed. MeJA accelerated fruit ripening by means of a transitory increase in the soluble solid content/titratable acidity ratio, anthocyanin accumulation and an increase in softening at day 5. The expression of several phenylpropanoid-related genes, primarily those associated with anthocyanin biosynthesis, was increased under MeJA treatment, which correlated with an increased accumulation of anthocyanin. MeJA also altered the expression profiles of some cell wall-modifying genes, namely, EG1 and XTH1, and these changes correlated with a transient reduction in the firmness of MeJA-treated fruits. MeJA-responsive elements were observed in the promoter region of the EG1 gene. MeJA also increased the expression of LOX, AOS and OPR3, genes involved in the biosynthesis of JAs, and these changes correlated with the transient activation of fruit ripening observed. Conversely, the expression of ethylene and lignin biosynthesis genes (ACS, ACO, CAD and POD27) increased in MeJA-treated fruits at day 9. The present findings suggest that JAs promote the ripening of non-climacteric fruits through their involvement in anthocyanin accumulation, cell wall modification and the biosynthesis of ethylene and JAs.

Topics: Acetates; Anthocyanins; Cell Wall; Cyclopentanes; Ethylenes; Fragaria; Fruit; Gene Expression; Gene Expression Regulation, Plant; Genes, Plant; Lignin; Oxylipins; Plant Development; Plant Proteins

Effect of pre-harvest methyl jasmonate (MeJA) and post-harvest 1-methylcyclopropene (1-MCP) treatments on broccoli floret glucosinolate (GS) concentrations and quinone reductase (QR, an in vitro anti-cancer biomarker) inducing activity were evaluated two days prior to harvest, at harvest and at 10, 20, and 30 days of post-harvest storage at 4 °C. MeJA treatments four days prior to harvest of broccoli heads was observed to significantly increase floret ethylene biosynthesis resulting in chlorophyll catabolism during post-harvest storage and reduced product quality. Post-harvest treatment with 1-methylcyclopropene (1-MCP), which competitively binds to protein ethylene receptors, maintained post-harvest floret chlorophyll concentrations and product visual quality in both control and MeJA-treated broccoli. Transcript abundance of BoPPH, a gene which is responsible for the synthesis of pheophytinase, the primary enzyme associated with chlorophyll catabolism in broccoli, was reduced by 1-MCP treatment and showed a significant, negative correlation with floret chlorophyll concentrations. The GS, glucobrassicin, neoglucobrassicin, and gluconasturtiin were significantly increased by MeJA treatments. The products of some of the GS from endogenous myrosinase hydrolysis [sulforaphane (SF), neoascorbigen (NeoASG), N-methoxyindole-3-carbinol (NI3C), and phenethyl isothiocyanate (PEITC)] were also quantified and found to be significantly correlated with QR. Sulforaphane, the isothiocyanate hydrolysis product of the GS glucoraphanin, was found to be the most potent QR induction agent. Increased sulforaphane formation from the hydrolysis of glucoraphanin was associated with up-regulated gene expression of myrosinase (BoMyo) and the myrosinase enzyme co-factor gene, epithiospecifier modifier1 (BoESM1). This study demonstrates the combined treatment of MeJA and 1-MCP increased QR activity without post-harvest quality loss.

Topics: Acetates; Brassica; Chlorophyll; Cyclopentanes; Cyclopropanes; Enzyme Activation; Ethylenes; Gene Expression Regulation, Plant; Glucosinolates; Hydrolysis; Models, Biological; NAD(P)H Dehydrogenase (Quinone); Oxidation-Reduction; Oxylipins; Pigmentation; Plant Growth Regulators; Time Factors

Green leaf volatiles (GLV), which are rapidly emitted by plants in response to insect herbivore damage, are now established as volatile defense signals. Receiving plants utilize these molecules to prime their defenses and respond faster and stronger when actually attacked. To further characterize the biological activity of these compounds we performed a microarray analysis of global gene expression. The focus of this project was to identify early transcriptional events elicited by Z-3-hexenol (Z-3-HOL) as our model GLV in maize (Zea mays) seedlings. The microarray results confirmed previous studies on Z-3-HOL -induced gene expression but also provided novel information about the complexity of Z-3-HOL -induced transcriptional networks. Besides identifying a distinct set of genes involved in direct and indirect defenses we also found significant expression of genes involved in transcriptional regulation, Ca(2+)-and lipid-related signaling, and cell wall reinforcement. By comparing these results with those obtained by treatment of maize seedlings with insect elicitors we found a high degree of correlation between the two expression profiles at this early time point, in particular for those genes related to defense. We further analyzed defense gene expression induced by other volatile defense signals and found Z-3-HOL to be significantly more active than methyl jasmonate, methyl salicylate, and ethylene. The data presented herein provides important information on early genetic networks that are activated by Z-3-HOL and demonstrates the effectiveness of this compound in the regulation of typical plant defenses against insect herbivores in maize.

Topics: Acetates; Animals; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Regulatory Networks; Genes, Plant; Herbivory; Hexanols; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Leaves; Reproducibility of Results; RNA, Messenger; Salicylates; Time Factors; Volatile Organic Compounds; Zea mays

An EST sequence, designated JnRAP2-like, was isolated from tissue at the heartwood/sapwood transition zone (TZ) in black walnut (Juglans nigra L). The deduced amino acid sequence of JnRAP2-like protein consists of a single AP2-containing domain with significant similarity to conserved AP2/ERF DNA-binding domains in other species. Based on multiple sequence alignment, JnRAP2-like appears to be an ortholog of RAP2.6L (At5g13330), which encodes an ethylene response element binding protein in Arabidopsis thaliana. Real-time PCR revealed that the JnRAP2-like was expressed most abundantly in TZ of trees harvested in fall when compared with other xylem tissues harvested in the fall or summer. Independent transgenic lines over-expressing JnRAP2-like in Arabidopsis developed dramatic ethylene-related phenotypes when treated with 50 µM methyl jasmonate (MeJA). Taken together, these results indicated that JnRAP2-like may participate in the integration of ethylene and jasmonate signals in the xylem and other tissues. Given the role of ethylene in heartwood formation, it is possible JnRAP2-like expression in the transition zone is part of the signal transduction pathway leading to heartwood formation in black walnut.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Arabidopsis; Cloning, Molecular; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Gene Order; Juglans; Molecular Sequence Data; Open Reading Frames; Oxylipins; Phenotype; Phylogeny; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Sequence Alignment; Signal Transduction; Transcription Factors; Transcription, Genetic; Wood

WRKY transcription factors are encoded by large gene families across the plant kingdom. So far, their biological and molecular functions in nonmodel plants, including pepper (Capsicum annuum) and other Solanaceae, remain poorly understood. Here, we report on the functional characterization of a new group I WRKY protein from pepper, termed CaWRKY58. Our data indicate that CaWRKY58 can be localized to the nucleus and can activate the transcription of the reporter β-glucuronidase (GUS) gene driven by the 35S core promoter with two copies of the W-box in its proximal upstream region. In pepper plants infected with the bacterial pathogen Ralstonia solanacearum, CaWRKY58 transcript levels showed a biphasic response, manifested in an early/transient down-regulation and late up-regulation. CaWRKY58 transcripts were suppressed by treatment with methyl jasmonate and abscisic acid. Tobacco plants overexpressing CaWRKY58 did not show any obvious morphological phenotypes, but exhibited disease symptoms of greater severity than did wild-type plants. The enhanced susceptibility of CaWRKY58-overexpressing tobacco plants correlated with the decreased expression of hypersensitive response marker genes, as well as various defence-associated genes. Consistently, CaWRKY58 pepper plants silenced by virus-induced gene silencing (VIGS) displayed enhanced resistance to the highly virulent R. solanacearum strain FJC100301, and this was correlated with enhanced transcripts of defence-related pepper genes. Our results suggest that CaWRKY58 acts as a transcriptional activator of negative regulators in the resistance of pepper to R. solanacearum infection.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Capsicum; Cell Nucleus; Cloning, Molecular; Cyclopentanes; Disease Resistance; Ethylenes; Gene Expression Regulation, Plant; Gene Silencing; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Protein Transport; Ralstonia solanacearum; Real-Time Polymerase Chain Reaction; RNA, Messenger; Salicylic Acid; Sequence Alignment; Transcription Factors; Transcription, Genetic

Ethylene-response factors (ERFs) play an important role in regulating gene expression in plant responses to biotic and abiotic stresses. In this study, a new ERF transcription factor, GmERF7, was isolated from soybean. Sequence analysis showed that GmERF7 contained an AP2/ERF domain with 58 amino acids, two putative nuclear localization signal (NLS) domains, an acidic amino acid-rich transcriptional activation domain and a conserved N-terminal motif [MCGGAI(I/L)]. The expression of GmERF7 was induced by drought, salt, methyl jasmonate (MeJA), ethylene (ETH) and abscisic acid (ABA) treatments. However, the expression of GmERF7 decreased under cold treatment. GmERF7 localized to the nucleus when transiently expressed in onion epidermal cells. Furthermore, GmERF7 protein bound to the GCC-box element in vitro and activated the expression of the β-glucuronidase (GUS) reporter gene in tobacco leaves. Activities of GmERF7 promoter (GmERF7P) upregulated in tobacco leaves with 10h drought, salt and ETH treatments. However, activities of GmERF7P decreased with 10h cold and ABA treatments. Overexpression of GmERF7 in tobacco plants led to higher levels of chlorophyll and soluble carbohydrates and a lower level of malondialdehyde compared with wild-type tobacco plants under salt stress conditions, which indicated that GmERF7 enhanced salt tolerance in transgenic plants.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Carbohydrates; Cell Nucleus; Chlorophyll; Cold Temperature; Cyclopentanes; DNA-Binding Proteins; Droughts; Ethylenes; Gene Expression Regulation, Plant; Glucuronidase; Glycine max; Malondialdehyde; Molecular Sequence Data; Nicotiana; Onions; Oxylipins; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Salt Tolerance; Salt-Tolerant Plants; Signal Transduction

Suspension-cultured cells of Vitis vinifera cv Monastrell were used to investigate the effects of methyljasmonate, ethylene and salicylic acid separately or in combination with cyclodextrins on both trans-resveratrol production and the induction of defense responses. The results showed that the addition of methyljasmonate or ethylene to suspension-cultured cells jointly treated with cyclodextrins and salicylic acid provoked a decrease of trans-resveratrol levels suggesting that salicylic acid has a negative and antagonistic effect with methyljasmonate or ethylene on trans-resveratrol production. Likewise, the exogenous application of these compounds induced the accumulation of pathogenesis-related proteins. Analysis of the extracellular proteome showed the presence of amino acid sequences homologous to an specific β-1,3-glucanase, class III peroxidases and a β-1,4-mannanase, which suggests that these signal molecules could play a role in mediating defense-related gene product expression in V. vinifera cv Monastrell. Apart from these inducible proteins, other proteins were found in both the control and elicited cell cultures of V. vinifera. These included class IV chitinase, polygalacturonase inhibitor protein and reticuline oxidase-like protein, suggesting that their expression is constitutive being involved in the modification of the cell wall architecture during cell culture growth and in the prevention of pathogen attack.

Topics: Acetates; Anti-Infective Agents; Cells, Cultured; Cyclodextrins; Cyclopentanes; Disease Resistance; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Resveratrol; Salicylic Acid; Signal Transduction; Stilbenes; Vitis

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

'Venture' and 'BabyGold 5' are two peach cultivars with a demonstrated resistance and susceptibility, respectively, to bacterial spot disease caused by Xanthomonas campestris pv. pruni (Xcp). To explore the differences between these cultivars at the molecular level, two PR1 (Pp-PR1a, Pp-PR1b) and three PR5 (Pp-TLP1, Pp-TLP2 and Pp-TLP3) genes were isolated from peach (Prunus persica L.) and investigated by in silico and in situ approaches. The analysis of gene expression by qRT-PCR indicated that all PR genes, except Pp-PR1a, were induced to a significantly higher degree in the resistant cultivar. In response to signaling molecules, Pp-PR1a was induced chiefly by SA treatment, while other PR genes were induced mainly by ethephon or MeJA treatments. The induction of the same set of PR genes in response to bacterial infection, MeJA or ethephon suggests the involvement of jasmonic acid (JA)/ethylene (ET)-signaling pathways in mediating resistance against Xcp, which is consistent with the potential hemibiotrophic nature of this bacterium. The identification of binding sites for ERF and MYC2 transcription factors in the promoter of Pp-TLP1 and Pp-TLP2 genes further supported the role of JA/ET pathways in the transcription regulation of these genes. The role of stomata in defense against Xcp was also investigated by measuring stomatal apertures in both 'Venture' and 'BabyGold 5' leaves after 1 and 3 HPI. While most stomata closed in both cultivars within 1 HPI, stomata reopened again at 3 HPI with a higher percentage recorded for 'BabyGold 5', suggesting a potential role of stomata in the susceptibility of this cultivar.

Topics: Acetates; Binding Sites; Cyclopentanes; Disease Resistance; Ethylenes; Gene Expression Regulation, Plant; Organophosphorus Compounds; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plant Stomata; Plants, Genetically Modified; Promoter Regions, Genetic; Prunus; RNA, Plant; Salicylic Acid; Signal Transduction; Xanthomonas campestris

The Madagascar periwinkle produces monoterpenoid indole alkaloids (MIA) of high interest due to their therapeutical values. The terpenoid moiety of MIA is derived from the methyl erythritol phosphate (MEP) and seco-iridoid pathways. These pathways are regarded as the limiting branch for MIA biosynthesis in C. roseus cell and tissue cultures. In previous studies, we demonstrated a coordinated regulation at the transcriptional and spatial levels of genes from both pathways. We report here on the isolation of the 5'-flanking region (1,049 bp) of the hydroxymethylbutenyl 4-diphosphate synthase (HDS) gene from the MEP pathway. To investigate promoter transcriptional activities, the HDS promoter was fused to GUS reporter gene. Agrobacterium-mediated transformation of young tobacco leaves revealed that the cloned HDS promoter displays a tissue-specific GUS staining restricted to the vascular region of the leaves and limited to a part of the vein that encompasses the phloem in agreement with the previous localization of HDS transcripts in C. roseus aerial organs. Further functional characterizations in stably or transiently transformed C. roseus cells allowed us to identify the region that can be consider as the minimal promoter and to demonstrate the induction of HDS promoter by several hormonal signals (auxin, cytokinin, methyljasmonate and ethylene) leading to MIA production. These results, and the bioinformatic analysis of the HDS 5'-region, suggest that the HDS promoter harbours a number of cis-elements binding specific transcription factors that would regulate the flux of terpenoid precursors involved in MIA biosynthesis.

Topics: 5' Flanking Region; Acetates; Base Sequence; Biosynthetic Pathways; Catharanthus; Cloning, Molecular; Cyclopentanes; Cytokinins; Enzymes; Erythritol; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Glucuronidase; Molecular Sequence Data; Nicotiana; Nucleotide Motifs; Organ Specificity; Oxylipins; Plant Leaves; Plants, Genetically Modified; Promoter Regions, Genetic; Secologanin Tryptamine Alkaloids; Sequence Analysis, DNA; Sequence Deletion; Sugar Phosphates; Suspensions; Transcription, Genetic

Complex defence signalling pathways, controlled by different hormones, are known to be involved in the reaction of plants to a wide range of biotic and abiotic stress factors. Here, we studied the differential expression of genes involved in stress and defence responses in systemic tissue of rice infected with the root knot nematode (RKN) Meloidogyne graminicola and the migratory root rot nematode Hirschmanniella oryzae, two agronomically important rice pathogens with very different lifestyles. qRT-PCR revealed that all investigated systemic tissues had significantly lower expression of isochorismate synthase, a key enzyme for salicylic acid production involved in basal defence and systemic acquired resistance. The systemic defence response upon migratory nematode infection was remarkably similar to fungal rice blast infection. Almost all investigated defence-related genes were up-regulated in rice shoots 3 days after root rot nematode attack, including the phenylpropanoid pathway, ethylene pathway and PR genes, but many of which were suppressed at 7 dpi. Systemic shoot tissue of RKN-infected plants showed similar attenuation of expression of almost all studied genes already at 3 dpi, with clear attenuation of the ethylene pathway and methyl jasmonate biosynthesis. These results provide an interesting starting point for further studies to elucidate how nematodes are able to suppress systemic plant defence mechanisms and the effect in multitrophic interactions.

Topics: Acetates; Animals; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Host-Parasite Interactions; Oryza; Oxylipins; Plant Diseases; Plant Proteins; Plant Roots; Transcriptome; Tylenchoidea

Ethylene response factors (ERFs) are a large family of transcription factors (TFs) that have diverse functions in plant development and immunity. However, very little is known about the molecular regulation of these TFs in stone fruits during disease incidence. In the present study, we describe the identification of five peach ERFs (Pp-ERFs), aiming to elucidate their potential roles in defense against Xanthomonas campestris pv. pruni (Xcp), the causal agent of bacterial spot disease. The phylogenetic analysis along with sequence comparisons indicated that all Pp-ERFs are transcriptional activators belonging to groups IX and IIV ERFs. The transactivation capacity of these proteins was verified in vivo where they all induced the expression of the GUS reporter gene and in a GCC-dependent manner. The nuclear localization was also confirmed for two of these proteins, Pp-ERF2.b and Pp-ERF2.c, after their transient expression in onion epidermal cells. The induction kinetics of Pp-ERFs after inoculation with Xcp was determined by qRT-PCR. Except for Pp-ERF2.b, transcript levels of Pp-ERFs increased strongly and rapidly in the resistant 'Venture' compared to the susceptible 'BabyGold 5' cultivar after infection with Xcp. In contrast, the expression of Pp-ERF2.b was several-fold higher in the susceptible cultivar after bacterial infection. The expression of Pp-ERFs was also monitored after treating with signaling compounds; salicylic acid (SA) (1 mM), ethephon (1 mM) and methyl jasmonate (MeJA) (50 μM). Although the results generally emphasize the role of ethylene/jasmonic acid (ET/JA) signaling pathways in regulating the expression of Pp-ERFs, there was a coordination of the timing of ET/JA responses, suggesting compensatory rather than synergistic interactions between these pathways during defense against Xcp.

Topics: Acetates; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Proteins; Prunus; Salicylic Acid; Signal Transduction; Time Factors; Transcription Factors; Xanthomonas campestris

The available literature is conflicting on the potential protection of plants against ozone (O(3)) injury by exogenous jasmonates, including methyl jasmonate (MeJA). Protective antagonistic interactions of O(3) and MeJA have been observed in some systems and purely additive effects in others. Here it is shown that chronic exposure to low to moderate O(3) concentrations (4-114 ppb; 12 h mean) and to MeJA induced additive reductions in carbon assimilation (A (n)) and root respiration (R (r)), and in calculated whole plant carbon balance. Neither this chronic O(3) regime nor MeJA induced emission of ethylene (ET) from the youngest fully expanded leaves. ET emission was induced by acute 3 h pulse exposure to much higher O(3) concentrations (685 ppb). ET emission was further enhanced in plants treated with MeJA. Responses of growth, allocation, photosynthesis, and respiration to moderate O(3) concentrations and to MeJA appear to be independent and additive, and not associated with emission of ET. These results suggest that responses of Pima cotton to environmentally relevant O(3) are not mediated by signalling pathways associated with ET and MeJA, though these pathways are inducible in this species and exhibit a synergistic O(3)×MeJA interaction at very high O(3) concentrations.

Topics: Acetates; Cyclopentanes; Ethylenes; Gases; Gossypium; Oxylipins; Ozone; Plant Growth Regulators; Plant Leaves; Plant Roots

Peach (Prunus persica) was chosen as a model to further clarify the physiological role of jasmonates (JAs) during fruit ripening. To this aim, the effect of methyl jasmonate (MJ, 0.88 mM), applied at a late stage (S3) of fruit development under field conditions (in planta), on the time-course of fruit ripening over a 14-day period was evaluated. As revealed by a non-destructive device called a DA-meter, exogenously applied MJ impaired the progression of ripening leading to less ripe fruit at harvest. To better understand the molecular basis of MJ interference with ripening, the time-course changes in the expression of ethylene-, cell wall-, and auxin-related genes as well as other genes (LOX, AOS and bZIP) was evaluated in the fruit mesocarp. Real-time PCR analyses revealed that transcript levels of ethylene-related genes were strongly affected. In a first phase (days 2 and/or 7) of the MJ response, mRNAs of the ethylene biosynthetic genes ACO1, ACS1 and the receptor gene ETR2 were strongly but transiently down-regulated, and then returned to or above control levels in a second phase (days 11 and/or 14). Auxin biosynthetic, conjugating, transport and perception gene transcripts were also affected. While biosynthetic genes (TRPB and IGPS) were up-regulated, auxin-conjugating (GH3), perception (TIR1) and transport (PIN1) genes were transiently but strongly down-regulated in a first phase, but returned to control levels subsequently. Transcript levels of two JA-related genes (LOX, AOS) and a developmentally regulated transcription factor (bZIP) were also affected, suggesting a shift ahead of the ripening process. Thus, in peach fruit, the transient slowing down of ripening by exogenous MJ was associated with an interference not only with ethylene but also with auxin-related genes.

Topics: Acetates; Cell Wall; Cyclopentanes; Down-Regulation; Ethylenes; Fruit; Gene Expression Profiling; Gene Expression Regulation, Plant; Indoleacetic Acids; Oxylipins; Plant Proteins; Prunus; Real-Time Polymerase Chain Reaction; RNA, Messenger; RNA, Plant; Seedlings; Signal Transduction; Time Factors; Up-Regulation

MicroRNAs (miRNAs) are small noncoding RNAs which post-transcriptionally regulate gene expression by directing mRNA cleavage or translational inhibition. miRNAs play multiple roles in the growth, development and stress responses in plants. However, little is known of the wounding-responsive miRNAs and their regulation. Here, we investigated the expression patterns of microR828 (miR828) on wounding in sweet potato (Ipomoea batatas cv Tainung 57). The expression of miR828 was only detected in leaves, and was induced by wounding rather than by ethylene, hydrogen peroxide (H2O2), methyl jasmonate or nitric oxide (NO). Moreover, cyclic guanosine monophosphate (cGMP) was necessary for miR828 accumulation in leaves on wounding. Two miR828 target candidates, named IbMYB and IbTLD, were obtained by cDNA cloning, and their mRNA cleavage caused by miR828 was confirmed by cleavage site mapping, agro-infiltration and transgenics studies. The reduction in IbMYB and IbTLD expression coincided with the induction of miR828, demonstrating that IbMYB and IbTLD might be miR828 targets. Furthermore, transgenic sweet potato overexpressing miR828 precursor affected lignin and H2O2 contents. These results showed that cGMP could regulate wounding-responsive miR828, which repressed the expression of IbMYB and IbTLD. Subsequently, lignin and H2O2 were accumulated to participate in defense mechanisms.

Topics: Acetates; Agrobacterium; Antioxidants; Base Sequence; Calcium; Cyclic ADP-Ribose; Cyclic GMP; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Hydrogen Peroxide; Ipomoea batatas; Lignin; MicroRNAs; Molecular Sequence Data; Niacinamide; Nitric Oxide; Okadaic Acid; Oxylipins; Phosphoprotein Phosphatases; Plant Proteins; Plants, Genetically Modified; Propanols; Protein Kinases; RNA, Messenger; Staurosporine; Stress, Mechanical

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

Three novel ethylene response factor (ERF) genes, BkERF1, BkERF2.1 and BkERF2.2, were isolated from a medicinal plant, Bupleurum kaoi. The deduced BkERFs contain a canonical nuclear localization signal and an ERF/AP2 DNA binding domain. RNA gel blot analysis revealed that BkERF1 and BkERF2.1 were ubiquitously expressed at low levels in all parts of mature plants, and that BkERF2.2 was expressed at moderate levels in vegetative tissues. Exogenous application of methyl jasmonate induced BkERF1/2.1/2.2 transcripts. BkERF2.2 transcript levels were slightly increased by addition of ethephon and salicylic acid. BkERFs were localized in the plant nucleus and functioned as transcriptional activators. In B. kaoi cells overexpressing BKERFs, inoculation with Botrytis cinerea increased expression of some defense genes which are associated with enhanced disease resistance. Similarly, overexpression of BkERFs in transgenic Arabidopsis thaliana resulted in elevated mRNA levels of the defense gene PDF1.2, and in enhanced resistance to B. cinerea. Collectively, these results provide evidence that BkERFs mediate the expression of defense-related genes in plants.

Topics: Acetates; Anti-Infective Agents; Arabidopsis; Arabidopsis Proteins; Botrytis; Bupleurum; Cyclopentanes; Defensins; DNA, Complementary; DNA, Plant; Ethylenes; Gene Expression Regulation, Plant; Organophosphorus Compounds; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Proteins; Plants, Genetically Modified; Salicylic Acid; Signal Transduction; Transcription Factors

Mitogen-activated protein kinase (MAPK) cascades play important roles in mediating pathogen responses and reactive oxygen species signaling. In plants, MAPKs are classified into four major groups (A-D). Previous studies have mainly focused on groups A and B, but little is known about group C. In this study, we functionally characterized a stress-responsive group C MAPK gene (GhMPK2) from cotton. Northern blot analysis indicated that GhMPK2 was induced not only by signaling molecules, such as ethylene and methyl jasmonate, but also by methyl viologen-mediated oxidative stress. Transgenic tobacco (Nicotiana tabacum) plants that overexpress GhMPK2 displayed enhanced resistance to fungal and viral pathogens, and the expression of the pathogenesis-related (PR) genes, including PR1, PR2, PR4, and PR5, was significantly increased. Interestingly, the transcription of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) was significantly upregulated in transgenic plants, suggesting that GhMPK2 positively regulates ethylene synthesis. Moreover, overexpression of GhMPK2 elevated the expression of several antioxidant enzymes, conferring on transgenic plants enhanced reactive oxygen species scavenging capability and oxidative stress tolerance. These results increased our understanding of the role of the group C GhMPK2 gene in multiple defense-signaling pathways, including those that are involved in responses to pathogen infection and oxidative stress.

Topics: Acetates; Amino Acid Oxidoreductases; Cyclopentanes; Enzyme Induction; Ethylenes; Fusarium; Gene Expression Regulation, Plant; Gossypium; Lyases; Mitogen-Activated Protein Kinases; Nicotiana; Oxidative Stress; Oxylipins; Phytophthora; Plant Diseases; Plants, Genetically Modified; Reactive Oxygen Species; Signal Transduction; Up-Regulation

The aim of this study was to investigate the connection between heat-induced ethylene signal changes and enhanced disease resistance. Heat enhanced ripening and elevated MaACO1 expression in naturally ripened bananas (NRB), while it delayed ripening and reduced MaACO1expression in the ethephon-treated bananas (ETB). However, in both cases, heat reduced lesion sizes infected by Colletotrichum musae. This indicates that heat-induced disease resistance in bananas was independent of ripening rate. The expression of MaERS1 gene was inhibited by heat treatment in both NRB and ETB, implying that heat as a physical signal could be sensed by banana fruits through the inhibition of ethylene receptor gene expression. The intensity of MaERF1 transcript signals was elevated in heated bananas, suggesting that the enhanced accumulation of MaERF1 transcript following heat treatment could play an important role in activation of the defense system. In ETB, inhibition of JA biosynthesis by application of IBU down-regulated the expression of MaERF and significantly weakened disease resistance, suggesting involvement of endogenous JA in induction of the gene expression, which was reconfirmed by the fact that exposure to exogenous MeJA following the combination of heat plus IBU treatment restored part of the gene expression. On the other hand, in NRB, application of IBU elevated level of MaERF1 expression at 24h and enhanced disease resistance, suggesting that, when banana was not exposed to ethephon, the expression of MaERF1 gene was not JA dependent, which was verified by the fact that MeJA application did not enhance MaERF1 gene expression. In conclusion, heat-induced disease resistance in harvested bananas could involve down-regulation of MaERS1 expression and up-regulation of MaERF1 expression and JA pathway could be involved in heat activation of the defense system in bananas exposed to ethephon.

Topics: Acetates; Amino Acid Oxidoreductases; Colletotrichum; Cyclooxygenase Inhibitors; Cyclopentanes; Down-Regulation; Ethylenes; Fruit; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant; Hot Temperature; Ibuprofen; Musa; Organophosphorus Compounds; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Proteins; Random Allocation; Receptors, Cell Surface; Signal Transduction; Up-Regulation

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

Dehydrins are highly hydrophilic proteins involved in playing key adaptive roles in response to abiotic stress conditions having dehydration as a common component. In the present study, a novel banana SK(3)-type dehydrin, MusaDHN-1, was identified and later characterized using transgenic banana plants to investigate its functions in abiotic stress tolerance. Expression profiling in native banana plants demonstrated that MusaDHN-1 was induced in leaves by drought, salinity, cold, oxidative and heavy metal stress as well as by treatment with signalling molecules like abscisic acid, ethylene and methyl jasmonate. Promoter analysis carried out by making a MusaDHN-1 promoter: β-glucuronidase fusion construct reconfirmed the abiotic stress inducibility of MusaDHN-1. Transgenic banana plants constitutively overexpressing MusaDHN-1 were phenotypically normal and displayed improved tolerance to drought and salt-stress treatments in both in vitro and ex vitro assays. Enhanced accumulation of proline and reduced malondialdehyde levels in drought and salt-stressed MusaDHN-1 overexpressing plants further established their superior performance in stressed conditions. This study is the first to report generation of transgenic banana plants engineered for improved drought and salt-stress tolerance.

Topics: Abscisic Acid; Acetates; Agrobacterium; Amino Acid Sequence; Blotting, Southern; Cyclopentanes; Droughts; Ethylenes; Gene Dosage; Gene Expression Regulation, Plant; Genes, Plant; Genetic Vectors; Malondialdehyde; Molecular Sequence Data; Musa; Oxylipins; Phylogeny; Plant Leaves; Plant Proteins; Plant Roots; Plant Somatic Embryogenesis Techniques; Plants, Genetically Modified; Proline; Promoter Regions, Genetic; Recombinant Fusion Proteins; Salt-Tolerant Plants; Sequence Alignment; Stress, Physiological

It has been known that methyl jasmonate (MeJA) interacts with ethylene to elicit resistance. In green mature tomato fruits (Lycopersicon esculentum cv. Lichun), 0.02mM MeJA increased the activity of 1-aminocyclopropane-1-carboxylate oxidase (ACO), and consequently influenced the last step of ethylene biosynthesis. Fruits treated with a combination of 0.02 MeJA and 0.02 α-aminoisobutyric acid (AIB, a competitive inhibitor of ACO) exhibited a lower ethylene production comparing to that by 0.02mM MeJA alone. The increased activities of defense enzymes and subsequent control of disease incidence caused by Botrytis cinerea with 0.2mM MeJA treatment was impaired by AIB as well. A close relationship (P<0.05) was found between the activity alterations of ACO and that of chitinase (CHI) and β-1,3-glucanase (GLU). In addition, this study further detected the changes of gene expressions and enzyme kinetics of ACO to different concentrations of MeJA. LeACO1 was found the principal member from the ACO gene family to respond to MeJA. Accumulation of LeACO1/3/4 transcripts followed the concentration pattern of MeJA treatments, where the largest elevations were reached by 0.2mM. For kinetic analysis, K(m) values of ACO stepped up during the experiment and reached the maximums at 0.2mM MeJA with ascending concentrations of treatments. V(max) exhibited a gradual increase from 3h to 24h, and the largest induction appeared with 1.0mM MeJA. The results suggested that ACO is involved in MeJA-induced resistance in tomato, and the concentration influence of MeJA on ACO was attributable to the variation of gene transcripts and enzymatic properties.

Topics: Acetates; Amino Acid Oxidoreductases; Aminoisobutyric Acids; Botrytis; Chitinases; Cyclopentanes; Ethylenes; Fruit; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Glucan 1,3-beta-Glucosidase; Oxylipins; Plant Growth Regulators; Plant Proteins; Solanum lycopersicum

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

The purpose of this study was to investigate the hormonal regulation of gummosis in grape hyacinth (Muscari armeniacum) bulbs, focusing especially on the chemical composition of the gums. The application of ethephon (2-chloroethylphosphonic acid), an ethylene-releasing compound, at 1% and 2% (w/w) in lanolin as well as ethylene induced gummosis in the bulbs within several days. Methyl jasmonate (JA-Me, 0.1-2% in lanolin) alone had no effect on gummosis. However, simultaneous application of JA-Me and ethephon led to extreme stimulation of ethephon-induced gummosis. Ethephon-induced gummosis in the bulbs depended on the maturation stage of the bulbs, increasing from April to July, but decreasing from August to September. Regardless of the presence of JA-Me, the application of ethephon to the inflorescence axis of grape hyacinths did not induce gummosis. Gel permeation chromatography analysis revealed that gums were homogenous polysaccharides with an average molecular mass of ca. 8.3 kDa. Analysis of the sugar composition of the gums after hydrolysis revealed that the molar ratio of Rha:Ara:Gal:GalA:GlcA was 25:10:40:7:15. These results suggest that principal factors of gummosis as well as the chemical composition of gums differ between species of bulbous plants.

Topics: Acetates; Chromatography, Ion Exchange; Cyclopentanes; Ethylenes; Hyacinthus; Molecular Weight; Organophosphorus Compounds; Oxylipins; Plant Growth Regulators; Plant Gums; Plant Roots; Seasons; Vitis

The Arabidopsis thaliana transcription factor gene AtMYB44 was induced within 10 min by treatment with methyl jasmonate (MeJA). Wound-induced expression of the gene was observed in local leaves, but not in distal leaves, illustrating jasmonate-independent induction at wound sites. AtMYB44 expression was not abolished in Arabidopsis mutants insensitive to jasmonate (coi1), ethylene (etr1), or abscisic acid (abi3-1) when treated with the corresponding hormones. Moreover, various growth hormones and sugars also induced rapid AtMYB44 transcript accumulation. Thus, AtMYB44 gene activation appears to not be induced by any specific hormone. MeJA-induced activation of jasmonate-responsive genes such as JR2, VSP, LOXII, and AOS was attenuated in transgenic Arabidopsis plants overexpressing the gene (35S:AtMYB44), but significantly enhanced in atmyb44 knockout mutants. The 35S:MYB44 and atmyb44 plants did not show defectiveness in MeJA-induced primary root growth inhibition, indicating that the differences in jasmonate-responsive gene expression observed was not due to alterations in the jasmonate signaling pathway. 35S:AtMYB44 seedlings exhibited slightly elevated chlorophyll levels and less jasmonate- induced anthocyanin accumulation, demonstrating suppression of jasmonate-mediated responses and enhancement of ABA-mediated responses. These observations support the hypothesis of mutual antagonistic actions between jasmonate- and abscisic acid-mediated signaling pathways.

Topics: Abscisic Acid; Acetates; Anthocyanins; Arabidopsis; Arabidopsis Proteins; Chlorophyll; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Regulation, Plant; Genes, abl; Oxylipins; Plant Growth Regulators; Plants, Genetically Modified; Receptors, Cell Surface; Signal Transduction; Transcription Factors; Transcriptional Activation

Natural rubber production in Hevea brasiliensis is determined by both tapping and ethephon frequencies. It is affected by a complex physiological disorder called tapping panel dryness. This syndrome is likely to be induced by environmental and latex harvesting stresses. Defence responses, including rubber biosynthesis, are dramatically mediated by wounding, jasmonate and ethylene (ET), among other factors. Using real-time RT-PCR, the effects of wounding, methyl jasmonate (MeJA) and ET on the relative transcript abundance of a set of 25 genes involved in their signalling and metabolic pathways were studied in the bark of 3-month-old epicormic shoots. Temporal regulation was found for 9 out of 25 genes. Wounding treatment regulated the transcript abundance of 10 genes. Wounding-specific regulation was noted for the HbMAPK, HbBTF3b, HbCAS1, HbLTPP and HbPLD genes. MeJA treatment regulated the transcript abundance of nine genes. Of these, the HbMYB, HbCAS2, HbCIPK and HbChi genes were shown to be specifically MeJA inducible. ET response was accompanied by regulation of the transcript abundance of eight genes, and six genes, HbETR2, HbEIN2, HbEIN3, HbCaM, HbPIP1 and HbQM, were specifically regulated by ET treatment. Additionally, the transcript level of the HbGP and HbACR genes was enhanced by all three treatments simultaneously. Overall, a large number of genes were found to be regulated 4 h after the treatments were applied. This study nevertheless revealed some jasmonic acid-independent wound signalling pathways in H. brasiliensis, provided a general characterization of signalling pathways and will serve as a new base from which to launch advanced studies of the network of pathways operating in H. brasiliensis.

Topics: Acetates; Cyclopentanes; DNA Primers; Ethylenes; Gene Expression Profiling; Hevea; Oxylipins; Plant Bark; Plant Diseases; Plant Proteins; Plant Shoots; Reverse Transcriptase Polymerase Chain Reaction; Transcription, Genetic; Wounds and Injuries

Ethylene-responsive factors (ERFs), within a subgroup of the AP2/ERF transcription factor family, are involved in diverse plant reactions to biotic or abiotic stresses. Here, we report that overexpression of an ERF gene from Brassica rapa ssp. pekinensis (BrERF4) led to improved tolerance to salt and drought stresses in Arabidopsis. It also significantly affected the growth and development of transgenic plants. We detected that salt-induced expressions of a transcriptional repressor gene, AtERF4, and some Ser/Thr protein phosphatase2C genes, ABI1, ABI2 and AtPP2CA, were suppressed in BrERF4-overexpressing Arabidopsis plants. Furthermore, BrERF4 was induced by treatment with ethylene or methyljasmonate, but not by abscisic acid or NaCl in B. rapa. These results suggest that BrERF4 is activated through a network of different signaling pathways in response to salinity and drought.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Brassica rapa; Cell Growth Processes; Cells, Cultured; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Oxylipins; Plant Growth Regulators; Plants, Genetically Modified; Repressor Proteins; Salt Tolerance; Stress, Physiological; Transgenes

The promoter of the pepper pathogen-induced membrane protein gene CaPIMP1 was analyzed by an Agrobacterium-mediated transient expression assay in tobacco leaves. Several stress-related cis-acting elements (GT-1, W-box and ABRE) are located within the CaPIMP1 promoter. In tobacco leaf tissues transiently transformed with a CaPIMP1 promoter-beta-glucuronidase (GUS) gene fusion, serially 5'-deleted CaPIMP1 promoters were differentially activated by Pseudomonas syringae pv. tabaci, ethylene, methyl jasmonate, abscisic acid, and nitric oxide. The -1,193 bp region of the CaPIMP1 gene promoter sequence exhibited full promoter activity. The -417- and -593 bp promoter regions were sufficient for GUS gene activation by ethylene and methyl jasmonate treatments, respectively. However, CaPIMP1 promoter sequences longer than -793 bp were required for promoter activation by abscisic acid and sodium nitroprusside treatments. CaPIMP1 expression was activated in pepper leaves by treatment with ethylene, methyl jasmonate, abscisic acid, beta-amino-n-butyric acid, NaCl, mechanical wounding, and low temperature, but not with salicylic acid. Overexpression of CaPIMP1 in Arabidopsis conferred hypersensitivity to mannitol, NaCl, and ABA during seed germination but not during seedling development. In contrast, transgenic plants overexpressing CaPIMP1 exhibited enhanced tolerance to oxidative stress induced by methyl viologen during germination and early seedling stages. These results suggest that CaPIMP1 expression may alter responsiveness to environmental stress, as well as to pathogen infection.

Topics: Abscisic Acid; Acetates; Adaptation, Physiological; Arabidopsis; Base Sequence; Capsicum; Cyclopentanes; Environment; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Membrane Proteins; Molecular Sequence Data; Nicotiana; Osmotic Pressure; Oxylipins; Plant Leaves; Plant Proteins; Promoter Regions, Genetic; Pseudomonas syringae; Sequence Analysis, DNA; Signal Transduction; Stress, Physiological

The effects of methyl jasmonate, salicylic acid and ethylene on alkaloid accumulation in in vitro cell suspension, hairy roots and rootless shoot cultures of Catharanthus roseus were analyzed. Ajmalicine, but not catharanthine, accumulation was promoted by jasmonate and ethylene treatments in cell suspensions. In hairy roots, jasmonate induced the accumulation of both alkaloids, whereas ethylene only induced catharanthine accumulation. In shoot cultures, positive effects of jasmonate and ethylene were recorded only in vindoline accumulation. Ethylene diminished catharanthine accumulation in these cultures. No effect of salicylic acid was observed in any of the studied in vitro culture systems.

Topics: Acetates; Catharanthus; Cells, Cultured; Cyclopentanes; Ethylenes; Oxylipins; Plant Roots; Plant Shoots; Salicylic Acid; Secologanin Tryptamine Alkaloids; Vinca Alkaloids

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 Arabidopsis gene AtLEC (At3g15356) gene encodes a putative 30-kDa protein with a legume lectin-like domain. Likely to classic legume lectin family of genes, AtLEC is expressed in rosette leaves, primary inflorescences, and roots, as observed in Northern blot analysis. The accumulation of AtLEC transcript is induced very rapidly, within 30 min, by chitin, a fungal wall-derived oligosaccharide elictor of the plant defense response. Transgenic Arabidopsis carrying an AtLEC promoter-driven beta-glucuronidase (GUS) construct exhibited GUS activity in the leaf veins, secondary inflorescences, carpel heads, and silique receptacles, in which no expression could be seen in Northern blot analysis. This observation suggests that AtLEC expression is induced transiently and locally during developmental processes in the absence of an external signal such as chitin. In addition, mechanically wounded sites showed strong GUS activity, indicating that the AtLEC promoter responds to jasmonate. Indeed, methyl jasmonate and ethylene exposure induced AtLEC expression within 3-6 h. Thus, the gene appears to play a role in the jasmonate-/ethylene-responsive, in addition to the chitin-elicited, defense responses. However, chitin-induced AtLEC expression was also observed in jasmonate-insensitive (coi1) and ethylene-insensitive (etr1-1) Arabidopsis mutants. Thus, it appears that chitin promotes AtLEC expression via a jasmonate- and/or ethylene-independent pathway.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Blotting, Northern; Chitin; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Glucuronidase; Molecular Sequence Data; Organ Specificity; Oxylipins; Plant Growth Regulators; Plant Lectins; Signal Transduction; Up-Regulation

Plant roots show an impressive degree of plasticity in adapting their branching patterns to ever-changing growth conditions. An important mechanism underlying this adaptation ability is the interaction between hormonal and developmental signals. Here, we analyze the interaction of jasmonate with auxin to regulate lateral root (LR) formation through characterization of an Arabidopsis thaliana mutant, jasmonate-induced defective lateral root1 (jdl1/asa1-1). We demonstrate that, whereas exogenous jasmonate promotes LR formation in wild-type plants, it represses LR formation in jdl1/asa1-1. JDL1 encodes the auxin biosynthetic gene ANTHRANILATE SYNTHASE alpha1 (ASA1), which is required for jasmonate-induced auxin biosynthesis. Jasmonate elevates local auxin accumulation in the basal meristem of wild-type roots but reduces local auxin accumulation in the basal meristem of mutant roots, suggesting that, in addition to activating ASA1-dependent auxin biosynthesis, jasmonate also affects auxin transport. Indeed, jasmonate modifies the expression of auxin transport genes in an ASA1-dependent manner. We further provide evidence showing that the action mechanism of jasmonate to regulate LR formation through ASA1 differs from that of ethylene. Our results highlight the importance of ASA1 in jasmonate-induced auxin biosynthesis and reveal a role for jasmonate in the attenuation of auxin transport in the root and the fine-tuning of local auxin distribution in the root basal meristem.

Topics: Acetates; Anthranilate Synthase; Arabidopsis; Arabidopsis Proteins; Biological Transport; Cyclopentanes; Ethylenes; Indoleacetic Acids; Mutation; Oxylipins; Plant Roots

Analysis of the promoters of defense-related genes is valuable for determining stress signaling and transcriptional activation during pathogen infection. Here, we have isolated and functionally characterized the promoter region of the pepper (Capsicum annuum) pectin methylesterase inhibitor 1 (CaPMEI1) gene in transiently transformed tobacco plants and stably transformed Arabidopsis plants. Among four 5' deletion constructs analyzed, the -958-bp CaPMEI1 promoter induced a high level of GUS reporter activity in tobacco leaf tissue, driven by pathogen infection as well as by ethylene and methyl jasmonate (MeJA) treatment. The 204-bp region from -958 bp to -754 bp of the CaPMEI1 promoter is responsible for the stress-responsive expression. In addition, the pepper transcription factor CARAV1 activated the CaPMEI1 promoter in tobacco leaves, whereas the transcription factor CAbZIP1 did not. In the transgenic Arabidopsis plants, the -958 bp CaPMEI1 promoter was functionally regulated by developmental cues, bacterial and oomycete pathogen infections, and treatment with ethylene and MeJA. Histochemical GUS staining analyses of Arabidopsis tissues revealed that the CaPMEI1 promoter was mainly activated in leaf veins in response to various biotic and abiotic stimuli. Together, these results suggest that CaPMEI1 promoter activation may be a critical molecular event for host defense response and ethylene- and MeJA-mediated CaPMEI1 gene expression.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Base Sequence; Capsicum; Carboxylic Ester Hydrolases; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Glucuronidase; Molecular Sequence Data; Oomycetes; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Pseudomonas syringae; Recombinant Fusion Proteins; Signal Transduction; Virulence; Xanthomonas campestris

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

Monitoring transcriptional reorganization triggered in response to a particular stress is an essential first step for the functional analysis of genes involved in the process. To characterize Cicer arietinum L. defence responses against Helicoverpa armigera feeding, transcript patterns elicited by both herbivore and mechanical wounding were profiled and compared, and the application of defence regulators was assessed. A combination of approaches was employed to develop transcript profiles, including suppression subtractive hybridization (SSH), macroarray, northern blot, and cluster analysis. Of the 63 unique genes isolated, 29 genes expressed differentially when Helicoverpa feeding and wounding responses were compared. Comparative macroarray analyses revealed that most of the Helicoverpa-induced transcripts were methyl jasmonate (MeJA) and ethylene (ET) regulated. The effects of mild insect infestation and the exogenous application of signalling compounds on larval feeding behaviour were also monitored. Bioassays were performed to measure dispersal percentage and growth of larvae on elicited plants. Larvae released on elicited plants had decreased larval performance, demonstrating the central role of induced plant defence against herbivory. Similarly, wounding and exogenous application of MeJA and ET also affected larval growth and feeding behaviour. Our results demonstrated that Helicoverpa attack up-regulated large transcriptional changes and induced chickpea defence responses. Therefore, the results of this study advance the understanding of non-model plant-insect interactions on a broader scale.

Topics: Acetates; Animals; Cicer; Cyclopentanes; Ecosystem; Ethylenes; Feeding Behavior; Gene Expression Profiling; Gene Expression Regulation, Plant; Molecular Sequence Data; Moths; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Proteins; Torsion, Mechanical

Dehydration-responsive element-binding proteins (DREBs) and ethylene-responsive element (ERE) binding factors are two major subfamilies of the AP2/ethylene-responsive element-binding protein family and play crucial roles in the regulation of abiotic- and biotic-stress responses, respectively. In the present work, we have reported a previously identified DREB-like factor, TINY, that was involved in both abiotic- and biotic-stress signaling pathways. TINY was capable of binding to both DRE and ERE with similar affinity and could activate the expression of reporter genes driven by either of these two elements in tobacco cells. The 15th amino acid in the APETALA2 (AP2)/ethylene-responsive element-binding factor domain was demonstrated to be essential for its specific binding to ERE, whereas the 14th and 19th amino acids were responsible for the binding to DRE. The expression of TINY was greatly activated by drought, cold, ethylene, and slightly by methyl jasmonate. Additionally, overexpression of TINY in Arabidopsis resulted in elevated expressions of both the DRE- and the ERE-containing genes. Moreover, the expression of DRE-regulated genes, such as COR6.6 and ERD10, was up-regulated upon ethylene treatment, and the expression of ERE-regulated genes, such as HLS1, was also increased by cold stress, when the expression of TINY was being induced. These results strongly suggested that TINY might play a role in the cross-talk between abiotic- and biotic-stress-responsive gene expressions by connecting the DRE- and ERE-mediated signaling pathways. The results herein might promote the understanding of the mechanisms of specific DNA recognition and gene expression regulation by DREBs.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cold Temperature; Cyclopentanes; Dehydration; Disasters; Ethylenes; Gene Expression Regulation, Plant; Homeodomain Proteins; Nuclear Proteins; Oxylipins; Plant Growth Regulators; Protein Structure, Tertiary; Response Elements; Signal Transduction

Colonization of Arabidopsis thaliana roots by nonpathogenic Pseudomonas fluorescens WCS417r bacteria triggers a jasmonate/ethylene-dependent induced systemic resistance (ISR) that is effective against a broad range of pathogens. Microarray analysis revealed that the R2R3-MYB-like transcription factor gene MYB72 is specifically activated in the roots upon colonization by WCS417r. Here, we show that T-DNA knockout mutants myb72-1 and myb72-2 are incapable of mounting ISR against the pathogens Pseudomonas syringae pv tomato, Hyaloperonospora parasitica, Alternaria brassicicola, and Botrytis cinerea, indicating that MYB72 is essential to establish broad-spectrum ISR. Overexpression of MYB72 did not result in enhanced resistance against any of the pathogens tested, demonstrating that MYB72 is not sufficient for the expression of ISR. Yeast two-hybrid analysis revealed that MYB72 physically interacts in vitro with the ETHYLENE INSENSITIVE3 (EIN3)-LIKE3 transcription factor EIL3, linking MYB72 function to the ethylene response pathway. However, WCS417r activated MYB72 in ISR-deficient, ethylene-insensitive ein2-1 plants. Moreover, exogenous application of the ethylene precursor 1-aminocyclopropane-1-carboxylate induced wild-type levels of resistance in myb72-1, suggesting that MYB72 acts upstream of ethylene in the ISR pathway. Collectively, this study identified the transcriptional regulator MYB72 as a novel ISR signaling component that is required in the roots during early signaling steps of rhizobacteria-mediated ISR.

Topics: Acetates; Amino Acids, Cyclic; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Regulation, Plant; Glucans; Mutagenesis, Insertional; Oxylipins; Plant Roots; Pseudomonas fluorescens; Signal Transduction; Transcription Factors

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

Ammonium is a central intermediate in the nitrogen metabolism of plants. We have previously shown that methyl jasmonate (MJ) not only increases the content of H(2)O(2), but also causes NH(4)(+) accumulation in rice leaves. More recently, H(2)O(2) is thought to constitute a general signal molecule participating in the recognition of and the response to stress factors. In this study, we examined the role of H(2)O(2) as a link between MJ and subsequent NH(4)(+) accumulation in detached rice leaves. MJ treatment resulted in an accumulation of NH(4)(+) in detached rice leaves, which was preceded by a decrease in the activity of glutamine synthetase (GS) and an increase in the specific activities of protease and phenylalanine ammonia-lyase (PAL). GS, PAL, and protease appear to be the enzymes responsible for the accumulation of NH(4)(+) in MJ-treated detached rice leaves. Dimethylthiourea (DMTU), a chemical trap for H(2)O(2), was observed to be effective in inhibiting MJ-induced NH(4)(+) accumulation in detached rice leaves. Scavengers of free radicals (sodium benzoate, SB, and glutathione, GSH), nitric oxide donor (N-tert-butyl-alpha-phenylnitrone, PBN), the inhibitors of NADPH oxidase (diphenyleneiodonium chloride, DPI, and imidazole, IMD), and inhibitors of phosphatidylinositol 3-kinase (wortmannin, WM, and LY 294002, LY), which have previously been shown to prevent MJ-induced H(2)O(2) production in detached rice leaves, inhibited MJ-induced NH(4)(+) accumulation. Similarly, changes in enzymes responsible for NH(4)(+) accumulation induced by MJ were observed to be inhibited by DMTU, SB, GSH, PBN DPI, IMD, WM, or LY. Seedlings of rice cultivar Taichung Native 1 (TN1) are jasmonic acid (JA)-sensitive and those of cultivar Tainung 67 (TNG67) are JA-insensitive. On treatment with JA, H(2)O(2) accumulated in the leaves of TN1 seedlings but not in the leaves of TNG67. Ethylene action inhibitor, silver thiosulfate, was observed to inhibit MJ- and abscisic acid-induced accumulation of NH(4)(+) and changes in enzymes responsible for NH(4)(+) accumulation in detached rice leaves, suggesting that the action of MJ and ABA is ethylene dependent.

Topics: Abscisic Acid; Acetates; Cyclopentanes; Ethylenes; Glutathione; Hydrogen Peroxide; Nitric Oxide Donors; Oryza; Oxylipins; Phosphoinositide-3 Kinase Inhibitors; Plant Leaves; Quaternary Ammonium Compounds; Seedlings; Sodium Benzoate; Thiourea

Aphids are major insect pests of plants that feed directly from the phloem. We used the model legume Medicago truncatula Gaert. (barrel medic) to elucidate host resistance to aphids and identified a single dominant gene which confers resistance to Acyrthosiphon kondoi Shinji (bluegreen aphid). To understand how this gene conditions resistance to bluegreen aphid, transcription profiling of 23 defense-related genes representing various signaling pathways was undertaken using a pair of near-isogenic lines that are susceptible or resistant to bluegreen aphid. All salicylic acid- and ethylene-responsive genes tested were induced by bluegreen aphid in resistant and susceptible plants, although there were some differences in the magnitude and kinetics of the induction. In contrast, 10 of 13 genes associated with the octadecanoid pathway were induced exclusively in the resistant plants following bluegreen aphid infestation. These results are in contrast to plant-pathogen interactions where similar sets of defense genes typically are induced in compatible interactions, but to a lesser degree and later than in incompatible interactions. Treatment of susceptible plants with methyl jasmonate reduced bluegreen aphid infestation but not to the same levels as the resistant line. Together, these results strongly suggest that the octadecanoid pathway is important for this naturally derived aphid resistance trait.

Topics: Acetates; Animals; Aphids; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Haplotypes; Immunity, Innate; Medicago truncatula; Models, Theoretical; Oxylipins; Phenotype; Phloem; Plant Diseases; Plant Growth Regulators; Reverse Transcriptase Polymerase Chain Reaction; Salicylic Acid

Jasmonates comprise a family of plant hormones that regulate gene expression to modulate diverse developmental and defensive processes. To screen a set of jasmonate-responsive Arabidopsis genes, we performed a microarray analysis using an Affymetrix GeneChip containing about 8,300 gene probes synthesized in situ. External treatment with 100 microM methyl jasmonate resulted in significant changes (more than twofold increases or decreases) in the expression levels of 137 genes in the rosette leaves of 5-week-old Arabidopsis plants. Of these, 74 genes were up-regulated, including those involved in jasmonate biosynthesis, defense responses, oxidative stress responses, senescence, and cell wall modification. In contrast, the expression of genes involved in chlorophyll constitution and photosynthesis was down-regulated. Most importantly, the jasmonate treatment significantly reduced transcripts of abscisic acid-responsive cold/drought-stress genes, which suggests that an antagonistic interaction occurs between the jasmonate and abscisic acid signaling pathways in abiotic stress responses. Northern blot analysis of some selected genes revealed that the jasmonate-responsive genes exhibited unique time-course expression patterns after the external jasmonate treatment. Based on the basic clustering of the genes, we established a likely regulation scenario: the genes induced early after treatment are involved in signaling mechanisms that activate or repress other genes, whereas intermediate- and late-accumulating genes are activated by the signaling mechanisms and are subsequently involved in the ultimate jasmonate-modulated cellular responses.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Oligonucleotide Array Sequence Analysis; Oxylipins; Up-Regulation

In this study, a pathogen-inducible ERF (ethylene-response factor) gene in wheat, designated TaERF3, was isolated and characterized in detail. The sequence of the TaERF3 protein possesses all of the traits commonly associated with ERFs, but its entire sequence shares low identity with other ERFs of transcription factor families. The results of assays on subcelluar localization, GCC box-binding ability, and transactivation activity indicated that TaERF3 is a nuclear targeting protein and functions as a GCC box-binding transcriptional activator. Following infection with Blumeria graminis, the induction peak of TaERF3 expression occurring at 12 h in the resistant line was about six times higher than that in its susceptible parent. Following infections with Fusarium graminearum or Rhizoctonia cerealis, the TaERF3 maximum inductions in the susceptible line occurring at 12 h were about three or six times higher than those in the resistant lines, whereas after 24 h or 48 h, the transcript inductions in the resistant lines were much higher than that in the susceptible line. Furthermore, the TaERF3 transcript peak induced by salicylic acid (SA) treatment occurred at 4 h, whereas the peaks induced by exogenous ethylene and methyl jasmonate (MeJA) occurred at 24 h, all of which were earlier than those induced by pathogens in the resistant lines. These results suggested that TaERF3 might be mainly involved in the active defence response to B. graminis at an earlier stage through SA signalling, and to F. graminearum and R. cerealis at a later stage through the ethylene/jasmonic acid signalling pathways.

Topics: Acetates; Amino Acid Sequence; Ascomycota; Base Sequence; Cyclopentanes; Ethylenes; Fusarium; Gene Expression Regulation, Plant; Kinetics; Molecular Sequence Data; Oxylipins; Phylogeny; Plant Proteins; Protein Structure, Tertiary; Rhizoctonia; Salicylic Acid; Sequence Alignment; Sequence Analysis, Protein; Signal Transduction; Trans-Activators; Triticum

To determine whether the Nicotiana tabacum preproHypSys homolog in Nicotiana attenuata (NapreproHypSys) mediates anti-herbivore responses, we silenced (IRsys) and ectopically over-expressed (OVsys) NapreproHypSys in N. attenuata. Neither herbivore simulation nor methyl jasmonate (MeJA) application increased transcripts in wild-type (WT) or transformed lines. Compared to WT plants, OVsys plants had marginally higher constitutive levels but normally induced levels of trypsin proteinase inhibitors (TPIs) and nicotine; IRsys plants did not differ from WT plants. Herbivory-associated signalling [salicylic acid-induced protein kinase (SIPK) activity, jasmonic acid (JA), jasmonic acid-isoleucine/leucine (JA-Ile/Leu) and ethylene production or perception] did not differ strongly among the lines, but JA, JA-Ile/Leu and ethylene were marginally higher in OVsys plants. Manduca sexta larval performance did not differ among the lines, but feeding induced levels of TPI and nicotine in OVsys plants and decreased them in IRsys plants relative to WT. The secondary metabolite profiles of plants transplanted into N. attenuata's native habitat in the Great Basin Desert (UT, USA) mirrored those of glasshouse-grown plants, and compared to WT plants, OVsys plants suffered marginally less damage from grasshoppers, mirids and flea beetles but did not differ in their ability to attract Geocoris predators. We conclude that NapreproHypSys does not play a central role in anti-herbivore defense signalling in this native tobacco.

Topics: Acetates; Animals; Cyclopentanes; Ethylenes; Feeding Behavior; Gene Expression Regulation, Plant; Glycopeptides; Hydroxyproline; Larva; Manduca; Nicotiana; Oxylipins; Peptides; Plants, Genetically Modified; RNA, Messenger; Signal Transduction

In tobacco (Nicotiana tabacum), Ralstonia solanacearum OE1-1 (RsOE1-1) is pathogenic, whereas R. solanacearum 8107 (Rs8107) is nonpathogenic and induces the hypersensitive response (HR). To elucidate the molecular mechanisms of plant-R. solanacearum interactions, we used differential display to isolate a cDNA fragment, A6, regulated in tobacco by inoculation with RsOE1-1. The deduced amino acid sequence predicted from full-length A6-cDNA showed similarity to small heat shock proteins from Arabidopsis (Arabidopsis thaliana; hypothetical protein), Medicago truncatula, and Cucumis melo; we therefore designated A6 to correspond to Ntshsp17 (for tobacco small heat shock protein 17). Recombinant Ntshsp17 overproduced in Escherichia coli exhibited molecular chaperone function. Expression of Ntshsp17 was increased in tobacco leaves inoculated with both RsOE1-1 and Rs8107. Expression was induced by heat treatment and by treatment with aminocyclopropane carboxylic acid, hydrogen peroxide, methyl jasmonate, and salicylic acid. Ntshsp17 expression was induced by inoculation with a HR and pathogenicity gene mutant of Rs8107 that does not induce the HR, but not by Agrobacterium-mediated transient expression of INF1, an HR elicitor. In Nbshsp17-silenced plants (an Ntshsp17 ortholog in Nicotiana benthamiana), expression of ETHYLENE-RESPONSE ELEMENT-BINDING PROTEIN, PATHOGENESIS-RELATED1a (PR1a), and PR4 genes was compromised, but expression of ELONGATION FACTOR1alpha was scarcely affected. Appearance of the HR was not affected in the silenced plants. In the silenced plants, growth of Rs8107 was accelerated. Bacterial growth and wilt symptoms elicited by RsOE1-1 were also accelerated in the silenced plants. These results indicate that this small heat shock protein might have a role in HR-independent defenses in Nicotiana plants.

Topics: Acetates; Algal Proteins; Amino Acid Sequence; Base Sequence; Cell Death; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Gene Silencing; Heat-Shock Proteins, Small; Host-Pathogen Interactions; Hot Temperature; Hydrogen Peroxide; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Diseases; Plant Leaves; Polymerase Chain Reaction; Potexvirus; Proteins; Pseudomonas; Ralstonia solanacearum; Salicylic Acid

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

Volatile esters, primarily synthesized in peel tissues, are major aromatic components of apple fruits [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. The use of cold storage combined with 1-methylcyclopropene (1-MCP) treatment prolongs the life of apples but represses the regeneration of esters during poststorage ripening. In this study, the regeneration of total esters was significantly increased in apple fruits treated with salicylic acid (SA) and Ethephon (ETH) that had been treated once or twice with 1-MCP. However, methyl jasmonate (MeJA) treatment resulted in regeneration of total esters after a single 1-MCP treatment. To determine the mechanism by which SA, ETH, and MeJA regulate ester regeneration, the apple alcohol acyltransferase gene (MdAAT2) was investigated at the mRNA, protein, and enzyme activity levels. Genes associated with ethylene perception were also investigated by RT-PCR. The results suggest that MdAAT2 controls ester regeneration and that MdETR1 plays a key role in ethylene perception and regulation of downstream MdAAT2 gene expression during poststorage. Ester compounds and concentrations differed in peels treated with different signal molecules, indicating that regulation of the pathway upstream of straight-chain ester biosynthesis depended on the regulation of lipoxygenase (LOX) and alcohol dehydrogenase (ADH) activity by SA, ETH, and MeJA during poststorage ripening.

Topics: Acetates; Acyltransferases; Cold Temperature; Cyclopentanes; Cyclopropanes; Esters; Ethylenes; Food Preservation; Fruit; Malus; Organophosphorus Compounds; Oxylipins; Plant Growth Regulators; Plant Proteins; Salicylic Acid; Volatilization

Innate immunity is initiated in animals and plants through the recognition of a variety of pathogen-associated molecules that in animals are called pathogen-associated molecular patterns and in plants are called elicitors. Some plant pathogen-derived elicitors have been identified as peptides, but peptide elicitors derived from the plant itself that activate defensive genes against pathogens have not been previously identified. Here, we report the isolation and characterization of a 23-aa peptide from Arabidopsis, called AtPep1, which activates transcription of the defensive gene defensin (PDF1.2) and activates the synthesis of H(2)O(2), both being components of the innate immune response. The peptide is derived from a 92-aa precursor encoded within a small gene that is inducible by wounding, methyl jasmonate, and ethylene. Constitutive expression of the AtPep1 precursor gene PROPEP1 in transgenic Arabidopsis plants causes a constitutive transcription of PDF1.2. When grown in soil, the transgenic plants exhibited an increased root development compared with WT plants and an enhanced resistance toward the root pathogen Pythium irregulare. Six paralogs of PROPEP1 are present in Arabidopsis, and orthologs have been identified in species of several agriculturally important plant families, where they are of interest for their possible use in crop improvement.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Defensins; Ethylenes; Gene Expression; Gene Expression Regulation, Plant; Hydrogen Peroxide; Immunity, Innate; Molecular Sequence Data; Oxylipins; Protein Precursors; Trans-Activators

A novel pathogen-induced gene encoding the RAV (Related to ABI3/VP1) transcription factor, CARAV1, was isolated from pepper leaves infected with Xanthomonas campestris pv. vesicatoria. CARAV1 contains two distinct DNA-binding domains AP2 and B3 uniquely found in higher plants. Transient expression analysis of the smGFP:CARAV1 fusion construct in Arabidopsis protoplasts and pepper epidermal cells revealed the CARAV1 protein to be localized in the nucleus. The N-terminal region of CARAV1 fused to the GAL4 DNA-binding domain was required to activate transcription of reporter genes in yeast. In yeast one-hybrid, the recognition of CAACA and CACCTG motifs also were essential for the CARAV1 protein to bind to a specific target gene and activate the reporter gene. The expression of the CARAV1 gene was strongly induced early in pepper leaves during the pathogen infection, abiotic elicitors and environmental stresses. CARAV1 transcripts were localized in the phloem cells of leaf tissues during pathogen infection and ethylene treatment. Ectopic expression of the CARAV1 gene in transgenic Arabidopsis plants induced some PR genes and enhanced resistance against infection by Pseudomonas syringae pv. tomato DC3000 and osmotic stresses by high salinity and dehydration. The CARAV1 promoter activation was induced by P. syringae pv. tabaci, salicylic acid and abscisic acid. These data suggest that pathogen- and abiotic stress-inducible CARAV1 functions as a transcriptional activator triggering resistance to bacterial infection and tolerance to osmotic stresses.

Topics: Abscisic Acid; Acetates; Adaptation, Physiological; Amino Acid Sequence; Arabidopsis; Capsicum; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Regulation, Plant; Hydrogen Peroxide; Immunity, Innate; In Situ Hybridization; Mannitol; Molecular Sequence Data; Oxylipins; Plant Proteins; Plants, Genetically Modified; Pseudomonas syringae; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sequence Homology, Amino Acid; Sodium Chloride; Transcription Factors; Water; Xanthomonas campestris

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

S-adenosylmethionine decarboxylase activity (SAMDC; EC 4.1.1.21) leads to spermidine and spermine synthesis through specific synthases which use putrescine, spermidine and decarboxylated S-adenosylmethionine as substrates. In order to better understand the regulation of polyamine (PA), namely spermidine and spermine, biosynthesis, a SAMDC cDNA of Datura stramonium was introduced in tobacco (Nicotiana tabacum L. cv. Xanthi) in antisense orientation under the CaMV 35S promoter, by means of Agrobacterium tumefaciens and leaf disc transformation. The effect of the genetic manipulation on PA metabolism, ethylene production and plant morphology was analysed in primary transformants (R0), and in the transgenic progeny (second generation, R1) of self-fertilised primary transformants, relative to empty vector-transformed (pBin19) and wild-type (WT) controls. All were maintained in vitro by micropropagation. Primary transformants, which were confirmed by Southern and northern analyses, efficiently transcribed the antisense SAMDC gene, but SAMDC activity and PA titres did not change. By contrast, in most transgenic R1 shoots, SAMDC activity was remarkably lower than in controls, and the putrescine-to-spermidine ratio was altered, mainly due to increased putrescine, even though putrescine oxidising activity (diamine oxidase, EC 1.4.3.6) did not change relative to controls. Despite the reduction in SAMDC activity, the production of ethylene, which shares with PAs the common precursor SAM, was not influenced by the foreign gene. Some plants were transferred to pots and acclimatised in a growth chamber. In these in vivo-grown second generation transgenic plants, at the vegetative stage, SAMDC activity was scarcely reduced, and PA titres did not change. Finally, the rhizogenic potential of in vitro-cultured leaf explants excised from antisense plants was significantly diminished as compared with WT ones, and the response to methyl jasmonate, a stress-mimicking compound, in terms of PA conjugation, was higher and differentially affected in transgenic leaf discs relative to WT ones. The effects of SAMDC manipulation are discussed in relation to plant generation, culture conditions and response to stress.

Topics: Acetates; Adenosylmethionine Decarboxylase; Biogenic Polyamines; Cyclopentanes; Datura stramonium; DNA, Antisense; DNA, Plant; Down-Regulation; Ethylenes; Gene Expression Regulation, Plant; Nicotiana; Oxylipins; Plant Leaves; Plant Roots; Plants, Genetically Modified; Putrescine; Spermidine

ERFs (ethylene-responsive element binding factors) belong to a large family of plant transcription factors that are found exclusively in plants. A small subfamily of ERF proteins can act as transcriptional repressors. The Arabidopsis genome contains eight ERF repressors, namely AtERF3, AtERF4, and AtERF7 to AtERF12. Members of ERF repressors show differential expression, suggesting that they may have different function. Using a transient expression system, we demonstrated that AtERF4, AtERF7, AtERF10, AtERF11 and AtERF12 can function as transcriptional repressors. The expression of AtERF4 can be induced by ethylene, jasmonic acid, and abscisic acid (ABA). By using green fluorescent protein fusion, we demonstrated that AtEFR4 accumulated in the nuclear bodies of Arabidopsis cells. Expression of 35S:AtERF4-GFP in transgenic Arabidopsis plants conferred an ethylene-insensitive phenotype and repressed the expression of Basic Chitinase and beta-1,3-Glucanase, the GCC-box-containing genes. In comparison with wild-type plants, 35S:AtERF4-GFP transgenic plants had decreased sensitivity to ABA and were hypersensitive to sodium chloride. The expression of the ABA responsive genes, ABI2, rd29B and rab18, was decreased in the 35S:AtERF4-GFP transgenic plants. Our study provides evidence that AtERF4 is a negative regulator capable of modulating ethylene and abscisic acid responses.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Glucuronidase; Green Fluorescent Proteins; Hypocotyl; Microscopy, Fluorescence; Nicotiana; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Roots; Plants, Genetically Modified; Protein Isoforms; Recombinant Fusion Proteins; Repressor Proteins; Transcription, Genetic

A large gene family encoding the putative cysteine-rich defensins was discovered in Medicago truncatula. Sixteen members of the family were identified by screening a cloned seed defensin from M. sativa (Gao et al. 2000) against the Institute for Genomic Research's (TIGR) M. truncatula gene index (MtGI version 7). Based on the comparison of their amino acid sequences, M. truncatula defensins fell arbitrarily into three classes displaying extensive sequence divergence outside of the eight canonical cysteine residues. The presence of Class II defensins is reported for the first time in a legume plant. In silico as well as Northern blot and RT-PCR analyses indicated these genes were expressed in a variety of tissues including leaves, flowers, developing pods, mature seed and roots. The expression of these genes was differentially induced in response to a variety of biotic and abiotic stimuli. For the first time, a defensin gene (TC77480) was shown to be induced in roots in response to infection by the mycorrhizal fungus, Glomus versiforme. Northern blot analysis indicated that the tissue-specific expression patterns of the cloned Def1 and Def2 genes differed substantially between M. truncatula and M. sativa. Furthermore, the induction profiles of the Def1 and Def2 genes in response to the signaling molecules methyl jasmonate, ethylene and salicylic acid differed markedly between these two legumes.

Topics: Acetates; Amino Acid Sequence; Blotting, Northern; Cloning, Molecular; Cyclopentanes; Databases, Nucleic Acid; DNA, Plant; Ethylenes; Expressed Sequence Tags; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes, Plant; Medicago truncatula; Molecular Sequence Data; Multigene Family; Oxylipins; Plant Growth Regulators; RNA, Plant; Salicylic Acid; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid

Pseudomonas syringae pv. tomato (Pst) causes a bacterial speck disease in tomato and Arabidopsis. In Chinese cabbage, in which host-pathogen interactions are not well understood, Pst does not cause disease but rather elicits a hypersensitive response. Pst induces localized cell death and H2O2 accumulation, a typical hypersensitive response, in infiltrated cabbage leaves. Pre-inoculation with Pst was found to induce resistance to Erwinia carotovora subsp. carotovora, a pathogen that causes soft rot disease in Chinese cabbage. An examination of the expression profiles of 12 previously identified Pst-inducible genes revealed that the majority of these genes were activated by salicylic acid or BTH; however, expressions of the genes encoding PR4 and a class IV chitinase were induced by ethephon, an ethylene-releasing compound, but not by salicylic acid, BTH, or methyl jasmonate. This implies that Pst activates both salicylate-dependent and salicylate-independent defense responses in Chinese cabbage.

Topics: Acetates; Blotting, Northern; Brassica; Cell Death; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Hydrogen Peroxide; Models, Genetic; Oxylipins; Plant Diseases; Plant Leaves; Pseudomonas syringae; Salicylic Acid; Time Factors

Suppression subtractive hybridisation was used to isolate 21 cDNAs ( bmi1- bmi21) up-regulated 1-5 h post-inoculation (hpi) in a barley ( Hordeum vulgare L. cv. Pallas) near-isogenic line (NIL) P11 ( Mla13) challenged with either avirulent or virulent isolates of Blumeria graminis f. sp. hordei. Transcriptional changes at these time-points are crucial for the Mla-mediated hypersensitive response [W.R. Bushnell and Z. Liu (1994) Physiol Mol Plant Pathol 44:389-402]. Seven sequences were up-regulated by 1 hpi, when the pathogen has formed only the primary germ tube. Some transcripts were similar to genes with a role in regulating programmed cell death in animals, including NF kappaB and oxysterol-binding protein. Moreover, bmi7, similar to rice resistance gene Xa21, was rapidly up-regulated in both compatible and incompatible interactions, but was then down-regulated by 5 hpi in the virulent interaction. Only nine of the transcripts were up-regulated in mlo5 resistance in cv. Pallas NIL P22, confirming differential pathway induction between Mla13 and mlo5. However, eight sequences up-regulated in the Mla13 response in P11 were already highly elevated in uninoculated mlo5 mutant P22, suggesting that they may be negatively regulated by wild-type Mlo. Regulation of bmi sequences was investigated using salicylic acid, methyl jasmonate, ethylene, H(2)O(2), abscisic acid, wounding and a glucan elicitor. No single stimulus up-regulated all genes, suggesting either combinations of these stimuli, or additional stimuli, are involved in early Mla13 and mlo5 resistances. Whereas H(2)O(2) up- or down-regulated 17 of the transcripts detected in Northern analyses, salicylic acid stimulated only down-regulation of 5 transcripts.

Topics: Abscisic Acid; Acetates; Apoptosis; Ascomycota; Blotting, Northern; Cyclopentanes; DNA, Complementary; Ethylenes; Gene Expression Regulation, Plant; Glucans; Hordeum; Hydrogen Peroxide; Immunity, Innate; Oxylipins; Plant Diseases; Plant Proteins; Salicylic Acid; Signal Transduction; Stress, Mechanical; Transcriptional Activation

Polyphenol oxidase (PPO; EC 1.10.3.2 or EC 1.14.18.1) takes part in the response of tomato plants (Lycopersicon esculentum Mill.) to wounding and herbivore attack, mediated by the octadecanoid wound-signaling pathway. Wounding and methyl jasmonate (MeJA) induce expression of ppo genes and markedly increase the level of the enzyme. We report that pretreatment with MeJA also markedly increased the ability of isolated tomato chloroplasts to import and process PPO precursors (pPPO). Pea (Pisum sativum L.) chloroplasts showed no such response. Wounding or ethylene alone was ineffective but ethylene was synergistic with MeJA. Treatment with MeJA conferred a strong binding of pPPO, or its processing intermediate, to thylakoids and subsequent translocation into the lumen and processing to the mature protein. The effect on PPO import and translocation was evident after 8-16 h exposure to MeJA. Membrane-bound pPPO was cross-linked to a proteinaceous component of the thylakoid translocation apparatus, apparently induced by MeJA. The import and processing of other nuclear-encoded thylakoid proteins were not affected by MeJA in tomato. A 90-kDa protein that co-fractionated with thylakoids was induced along with the increase in competence for PPO import, and was identified as the proteinase-inhibitor multicystatin. It is concluded that the 90-kDa protein observed is part of the MeJA-induced defense response of tomato, not a component of the thylakoid translocation apparatus.

Topics: Acetates; Amino Acid Sequence; Biological Transport, Active; Catechol Oxidase; Chloroplasts; Cyclopentanes; Cystatins; Enzyme Precursors; Ethylenes; Molecular Sequence Data; Oxylipins; Pisum sativum; Plant Proteins; Solanum lycopersicum; Thylakoids

Capsicum annuum tobacco mosaic virus (TMV)-induced clone 1 (CaTin1) gene was expressed early during incompatible interaction of hot pepper (Caspsicum annuum) plants with TMV and Xanthomonas campestris. RNA-blot analysis showed that CaTin1 gene was expressed only in roots in untreated plants and induced mainly in leaf in response to ethylene, NaCl, and methyl viologen but not by salicylic acid and methyl jasmonate. The ethylene dependence of CaTin1 induction upon TMV inoculation was demonstrated by the decrease of CaTin1 expression in response to several inhibitors of ethylene biosynthesis or its action. Transgenic tobacco (Nicotiana tabacum) plants expressing CaTin1 gene in sense- or antisense-orientation showed interesting characteristics such as the accelerated growth and the enhanced resistance to biotic as well as abiotic stresses. Such characteristics appear to be caused by the elevated level of ethylene and H2O2. Moreover, in transgenic plants expressing antisense CaTin1 gene, the expression of some pathogenesis-related genes was enhanced constitutively, which may be mainly due to the increased ethylene level. The promoter of CaTin1 has four GCC-boxes, two AT-rich regions, and an elicitor-inducible W-box. The induction of the promoter activity by ethylene depends on GCC-boxes and by TMV on W-box. Taken together, we propose that the CaTin1 up-regulation or down-regulation interferes with the redox balance of plants leading to the altered response to ethylene and biotic as well as abiotic stresses.

Topics: Acetates; Amino Acid Sequence; Capsicum; Cyclopentanes; Disasters; Ethylenes; Gene Expression Regulation, Plant; Glucuronidase; Homeostasis; Hydrogen Peroxide; Immunity, Innate; Molecular Sequence Data; Oxidation-Reduction; Oxylipins; Paraquat; Plant Diseases; Plant Proteins; Plant Roots; Plants, Genetically Modified; Promoter Regions, Genetic; Recombinant Fusion Proteins; Salicylic Acid; Sequence Homology, Amino Acid; Sodium Chloride; Tobacco Mosaic Virus; Xanthomonas campestris

Experiments with several Arabidopsis thaliana mutants have revealed a web of interactions between hormonal signaling. Here, we show that the Arabidopsis mutant radical-induced cell death1 (rcd1), although hypersensitive to apoplastic superoxide and ozone, is more resistant to chloroplastic superoxide formation, exhibits reduced sensitivity to abscisic acid, ethylene, and methyl jasmonate, and has altered expression of several hormonally regulated genes. Furthermore, rcd1 has higher stomatal conductance than the wild type. The rcd1-1 mutation was mapped to the gene At1g32230 where it disrupts an intron splice site resulting in a truncated protein. RCD1 belongs to the (ADP-ribosyl)transferase domain-containing subfamily of the WWE protein-protein interaction domain protein family. The results suggest that RCD1 could act as an integrative node in hormonal signaling and in the regulation of several stress-responsive genes.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Chloroplasts; Cold Temperature; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Glucose; Molecular Sequence Data; Nuclear Proteins; Oxylipins; Physical Chromosome Mapping; Plants, Genetically Modified

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

Conifer stem pest resistance includes constitutive defenses that discourage invasion and inducible defenses, including phenolic and terpenoid resin synthesis. Recently, methyl jasmonate (MJ) was shown to induce conifer resin and phenolic defenses; however, it is not known if MJ is the direct effector or if there is a downstream signal. Exogenous applications of MJ, methyl salicylate, and ethylene were used to assess inducible defense signaling mechanisms in conifer stems. MJ and ethylene but not methyl salicylate caused enhanced phenolic synthesis in polyphenolic parenchyma cells, early sclereid lignification, and reprogramming of the cambial zone to form traumatic resin ducts in Pseudotsuga menziesii and Sequoiadendron giganteum. Similar responses in internodes above and below treated internodes indicate transport of a signal giving a systemic response. Studies focusing on P. menziesii showed MJ induced ethylene production earlier and 77-fold higher than wounding. Ethylene production was also induced in internodes above the MJ-treated internode. Pretreatment of P. menziesii stems with the ethylene response inhibitor 1-methylcyclopropene inhibited MJ and wound responses. Wounding increased 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase protein, but MJ treatment produced a higher and more rapid ACC oxidase increase. ACC oxidase was most abundant in ray parenchyma cells, followed by cambial zone cells and resin duct epithelia. The data show these MJ-induced defense responses are mediated by ethylene. The cambial zone xylem mother cells are reprogrammed to differentiate into resin-secreting epithelial cells by an MJ-induced ethylene burst, whereas polyphenolic parenchyma cells are activated to increase polyphenol production. The results also indicate a central role of ray parenchyma in ethylene-induced defense.

Topics: Acetates; Cyclopentanes; Ethylenes; Oxidoreductases; Oxylipins; Plant Stems; Prions; Pseudotsuga; Resins, Plant

Ethylene responsive factors (ERFs) are important plant-specific transcription factors, some of which have been demonstrated to interact with the ethylene-responsive GCC box and the dehydration-responsive element (DRE); however, data on the roles of ERF proteins in connection with various signaling pathways are limited. In this research, we used the GCC box, an essential cis-acting element responsive to ethylene and methyl jasmonate (MeJA), as bait in a yeast one-hybrid system to isolate transcription factors from tomato (Lycopersicon esculentum Mill.). One of the cDNAs, which was designated Jasmonate and Ethylene Response Factor 1 (JERF1), encodes an ERF protein, containing a conserved ERF DNA-binding motif and functioning as a transcriptional activator in yeast through targeting to the nucleus in onion (Allium cepa L.) epidermal cells. Biochemical analysis revealed that JERF1 bound not only to the GCC box but also to the DRE sequence. Expression of the JERF1 gene in tomato was induced by ethylene, MeJA, abscisic acid (ABA) and salt treatment, indicating that JERF1 might act as a connector among different signal transduction pathways. Further research with transgenic JERF1 tobacco (Nicotiana tabacum L.) plants indicated that overexpressing JERF1 activated expression of GCC box-containing genes such as osmotin, GLA, Prb-1b and CHN50 under normal growth conditions, and subsequently resulted in enhanced tolerance to salt stress, suggesting that JERF1 modulates osmotic tolerance by activation of downstream gene expression through interaction with the GCC box or DRE.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Cyclopentanes; DNA, Complementary; DNA, Plant; Ethylenes; Gene Expression Regulation, Plant; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Growth Regulators; Plants, Genetically Modified; Regulatory Sequences, Nucleic Acid; Signal Transduction; Sodium Chloride; Solanum lycopersicum; Transcription Factors

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

Plant secondary metabolism significantly contributes to defensive measures against adverse abiotic and biotic cues. To investigate stress-induced, transcriptional alterations of underlying effector gene families, which encode enzymes acting consecutively in secondary metabolism and defense reactions, a DNA array (MetArray) harboring gene-specific probes was established. It comprised complete sets of genes encoding 109 secondary product glycosyltransferases and 63 glutathione-utilizing enzymes along with 62 cytochrome P450 monooxygenases and 26 ABC transporters. Their transcriptome was monitored in different organs of unstressed plants and in shoots in response to herbicides, UV-B radiation, endogenous stress hormones, and pathogen infection. A principal component analysis based on the transcription of these effector gene families defined distinct responses and crosstalk. Methyl jasmonate and ethylene treatments were separated from a group combining reactions towards two sulfonylurea herbicides, salicylate and an avirulent strain of Pseudomonas syringae pv. tomato . The responses to the herbicide bromoxynil and UV-B radiation were distinct from both groups. In addition, these analyses pinpointed individual effector genes indicating their role in these stress responses. A small group of genes was diagnostic in differentiating the response to two herbicide classes used. Interestingly, a subset of genes induced by P. syringae was not responsive to the applied stress hormones. Small groups of comprehensively induced effector genes indicate common defense strategies. Furthermore, homologous members within branches of these effector gene families displayed differential expression patterns either in both organs or during stress responses arguing for their non-redundant functions.

Topics: Acetates; Arabidopsis; Cluster Analysis; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Herbicides; Nitriles; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Growth Regulators; Pseudomonas syringae; Salicylic Acid; Sulfonamides; Sulfonylurea Compounds; Transcription, Genetic; Triazines; Urea

We studied the local response to wounding in Arabidopsis thaliana leaves using a two-step microarray analysis. A microarray containing 3500 cDNA clones was first screened to enrich for genes affected by wounding in the immediate vicinity of the wound (4 h post wounding). 359 non-redundant putative wound responsive genes were then spotted on a smaller wound-response array for detailed analysis of spatial expression (local, adjacent and systemic), timing of expression (0.5, 4, 8, 17 h), and effect of hormone treatments (methyl jasmonate, ethylene and abscisic acid). Our results show that genes that respond early at the site of the wound also respond throughout the plant, with similar kinetics. Early-induced genes which respond systemically encode predominantly signal transduction and regulatory factors (36%), and the expression of many of them is also controlled by methyl jasmonate (about 35% of the 36%). Genes specific to the wound site and the wounded leaf have a slower response to wounding and are mainly metabolic genes. At the wound, many genes of the lignin biosynthesis pathway were induced. In silico analysis of the 5' promoter regions of genes affected by wounding revealed G-box-related motifs in a significant proportion of the promoters. These results show that the establishment of a systemic response to wounding is a priority for the plant, and that the local response at the wound site is established later. Ethylene and abscisic acid are involved in the local response, regulating repression of photosynthetic genes and expression of drought responsive genes respectively.

Topics: Abscisic Acid; Acetates; Arabidopsis; Blotting, Northern; Cluster Analysis; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Leaves; Promoter Regions, Genetic; Response Elements; RNA, Plant; Stress, Mechanical; Time Factors

Putrescine N-methyltransferase (PMT) catalyzes the first committed step of nicotine biosynthesis, converting putrescine into N-methylputrescine. A variety of chemical, environmental, and developmental cues have been implicated in its regulation. Here we have examined the differential expression of beta-glucuronidase (GUS) transgenes under the control of the transcriptional regulatory sequences of four distinct members of the NtPMT gene family from tobacco (Nicotiana tabacum L.). BY-2 cell cultures expressing various NtPMT promoter-GUS constructs were examined for their response to treatment with various combinations of methyl jasmonate (MeJA), auxin (AUX), and ethylene (ETH). All four NtPMT gene promoters examined were inducible by MeJA, although the extent of the induction varied dramatically, with the NtPMT1a promoter being the most responsive. High AUX levels in the cell growth media repressed NtPMT::GUS transgene expression and inhibited their MeJA-induced transcription. Treatment of BY-2 cells with ETH alone did not result in a significant alteration in NtPMT::GUS expression. However, similar to AUX, ETH treatment led to the suppression of MeJA-induced transcription. Detailed deletion analysis of the NtPMT1a gene promoter showed that as little as 111 bp upstream of the transcriptional start site were sufficient to confer MeJA-responsiveness. Deletion of a conserved G-box element (GCACGTTG) at -103 to -96 bp completely abolished MeJA-responsiveness. Further mutagenesis studies revealed that in addition to a functional G-box, MeJA-responsiveness of the NtPMT1a promoter also required a TA-rich region and a GCC-motif (TGCGCCC) located at -80 to -69 bp and -62 to -56 bp relative to the start site, respectively. A synthetic G-box tetramer (4 X syn G-box) fused to a -83 bp fragment from the NtPMT1a promoter (containing the TA-rich region, GCC-box, and TATA-box) displayed a 30-fold induction by MeJA treatment, whereas when the 4 X syn G-box was fused to a minimal (-46 bp) promoter fragment derived from the CaMV 35S gene, no induction by MeJA treatment was detected. Our results indicate that multiple intersecting signal transduction pathways and different transcriptional regulatory factors are involved in mediating JA-responsiveness of NtPMT expression in tobacco.

Topics: Acetates; Base Sequence; Binding Sites; Cells, Cultured; Cyclopentanes; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Glucuronidase; Indoleacetic Acids; Methyltransferases; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Growth Regulators; Promoter Regions, Genetic; Recombinant Fusion Proteins; Regulatory Sequences, Nucleic Acid; Response Elements; TATA Box; Transformation, Genetic

Glucosinolates are natural plant products that function in the defense toward herbivores and pathogens. Plant defense is regulated by multiple signal transduction pathways in which salicylic acid (SA), jasmonic acid, and ethylene function as signaling molecules. Glucosinolate content was analyzed in Arabidopsis wild-type plants in response to single or combinatorial treatments with methyljasmonate (MeJA), 2,6-dichloro-isonicotinic acid, ethylene, and 2,4-dichloro-phenoxyacetic acid, or by wounding. In addition, several signal transduction mutants and the SA-depleted transgenic NahG line were analyzed. In parallel, expression of glucosinolate biosynthetic genes of the CYP79 gene family and the UDPG:thiohydroximate glucosyltransferase was monitored. After MeJA treatment, the amount of indole glucosinolates increased 3- to 4-fold, and the corresponding Trp-metabolizing genes CYP79B2 and CYP79B3 were both highly induced. Specifically, the indole glucosinolate N-methoxy-indol-3-ylmethylglucosinolate accumulated 10-fold in response to MeJA treatment, whereas 4-methoxy-indol-3-ylmethylglucosinolate accumulated 1.5-fold in response to 2,6-dichloro-isonicotinic acid. In general, few changes were seen for the levels of aliphatic glucosinolates, although increases in the levels of 8-methylthiooctyl glucosinolate and 8-methylsulfinyloctyl glucosinolate were observed, particularly after MeJA treatments. The findings were supported by the composition of glucosinolates in the coronatine-insensitive mutant coi1, the ctr1 mutant displaying constitutive triple response, and the SA-overproducing mpk4 and cpr1 mutants. The present data indicate that different indole glucosinolate methoxylating enzymes are induced by the jasmonate and the SA signal transduction pathways, whereas the aliphatic glucosinolates appear to be primarily genetically and not environmentally controlled. Thus, different defense pathways activate subsets of biosynthetic enzymes, leading to the accumulation of specific glucosinolates.

Topics: 2,4-Dichlorophenoxyacetic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Cytochrome P-450 Enzyme System; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Glucosinolates; Immunity, Innate; Indoleacetic Acids; Isoenzymes; Isonicotinic Acids; Mixed Function Oxygenases; Oxylipins; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Stress, Mechanical

The structure and expression of a novel senescence-associated gene (SPA15) of sweet potato were characterized. The protein coding region of the gene consists of 13 exons encoding 420 amino acids. Apparent homologues of this sweet potato gene are found in a variety of dicot and monocot plants, but not in animals or microorganisms. Examination of the expression patterns of the SPA15 gene in sweet potato reveals that the transcripts of SPA15 are specifically induced in the senescing leaves, and the temporal profile of SPA15 protein accumulation is correlated with that of SPA15 transcripts. Studies on the distribution of SPA15 homologue in rice plants also indicate that SPA15 homologue is up-regulated specifically in senescing rice leaves. Treatment of detached sweet potato leaves with phytohormones including ethylene, methyl jasmonate, salicylic acid and abscisic acid resulted in a high-level induction of SPA15. Immunoelectron microscopic analysis demonstrates that SPA15 is specifically associated with the cell wall. The potential role for SPA15 during leaf senescence is discussed.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Arabidopsis; Cloning, Molecular; Cyclopentanes; DNA, Complementary; DNA, Plant; Ethylenes; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Ipomoea batatas; Microscopy, Immunoelectron; Molecular Sequence Data; Oryza; Oxylipins; Plant Growth Regulators; Plant Leaves; Plant Proteins; RNA, Messenger; Salicylic Acid; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid

Incompatible plant-pathogen interactions result in the rapid cell death response known as hypersensitive response (HR) and activation of host defense related genes. To understand the cellular mechanism controlling defense response better, a novel pathogenesis-related (PR) gene and putative cell wall protein gene, CaTin2, was isolated through differential screening of a hot pepper cDNA library and characterized. CaTin2 gene was locally and systemically induced in hot pepper plants upon TMV-P0 inoculation which induces HR. However, CaTin2 gene wasn't regulated by bacterial HR-specific signal pathway. The full-length cDNA for CaTin2, which is 864 nucleotides long, contained the open reading frame of 200 amino acids including cell wall targeting sequences of 26 amino acids. CaTin2 gene has no sequence similarity with other cell wall protein genes except the signal sequence and exists as only one copy in hot pepper genome. CaTin2 gene contains repeated helix-turn-helix motif consisting of 39 amino acids. CaTin2 mRNA accumulation was induced in response to various treatments such as ethylene, SA, MeJA, ABA, methyl viologen, NaCl and wounding at early time points. Subcelluar localization of CaTin2 was confirmed in the cell wall in hot pepper leaves by making CaTin2::smGFP fusion protein. The transgenic plants overexpressing CaTin2 cDNA were resistant to TMV and CMV inoculation. From these results, CaTin2 gene may encode a virus-related new cell wall protein member.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Capsicum; Cucumovirus; Cyclopentanes; Darkness; DNA, Complementary; Ethylenes; Gene Expression Regulation, Plant; Green Fluorescent Proteins; Luminescent Proteins; Microscopy, Fluorescence; Molecular Sequence Data; Oxylipins; Paraquat; Plant Diseases; Plant Proteins; Recombinant Fusion Proteins; Salicylic Acid; Sequence Analysis, DNA; Sodium Chloride; Stress, Mechanical; Tobacco Mosaic Virus; Xanthomonas campestris

Sulfurtransferases (STs) and beta-cyano- l-alanine synthase (CAS) are suggested to be involved in cyanide detoxification. Therefore, the accumulation of ST1 and CAS RNAs, and the ST and CAS protein levels and enzyme activities were determined in Arabidopsis thaliana Heynh. plants grown under different conditions. Senescence-associated processes were successfully induced by natural aging, by jasmonate methyl ester and by darkness in whole plants and detached leaves, as demonstrated by the expression of the senescence marker genes SAG12 and SAG13. However, the changes in RNA accumulation and protein levels of ST and CAS did not correlate with the expression of these senescence marker genes; the specific ST and CAS activities either decreased (ST) or increased (CAS). In another experiment, Arabidopsis plants were sprayed with cyanide to investigate the role of ST and CAS in cyanide detoxification. The expression of ST and CAS at the RNA and protein levels, and also the enzyme activities, remained equal in cyanide-treated and control plants. Incubation with 1-aminocyclopropane-1-carboxylic acid, the precursor of ethylene, increased while fumigation with ethylene decreased expression and activity of ST and CAS. In summary, cyanide does not induce the expression or enhance the activity of ST and CAS in Arabidopsis. For both proteins the evidence for a role in cyanide detoxification or induced senescence is low.

Topics: Acetates; Amino Acids, Cyclic; Apoptosis; Arabidopsis; Cyclopentanes; Ethylenes; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Lyases; Oxylipins; Potassium Cyanide; Sulfurtransferases; Thiocyanates

Identification of Solanum tuberosum genes responsive to culture filtrates (CF) from Erwinia carotovora subsp. carotovora led to the isolation of a full-length cDNA with high sequence similarity to several alcohol dehydrogenases. Accumulation of transcripts corresponding to this defence-related alcohol dehydrogenase (drd-1) was rapidly induced in CF-treated and wounded plants. The gene was also responsive to molecules involved in defence signalling such as salicylic acid, methyl jasmonate and ethylene. To elucidate the biochemical function of DRD-1, its cDNA was expressed in Escherichia coli. Enzymatic assays revealed that DRD-1 is an alcohol:NADP+ oxidoreductase with preference for various aromatic and aliphatic aldehydes. The enzyme exhibited high activity with several aldehydes including 2-methoxybenzaldehyde, 3-methoxybenzaldehyde, salicylaldehyde, o-vanillin, cinnamaldehyde, hydrocinnamaldehyde, hexanal and octanal. Identification of the reaction product by thin-layer chromatography confirmed the reduction of aldehydes to alcohols. Enzymatic activity measured with 2-methoxybenzaldehyde as a substrate was increased in salicylic acid- or methyl jasmonate-treated plants. These data suggest that DRD-1 may play an important role in potato defence response to Erwinia carotovora.

Topics: Acetates; Alcohol Oxidoreductases; Amino Acid Sequence; Chromatography, Thin Layer; Culture Media, Conditioned; Cyclopentanes; DNA, Complementary; Enzyme Activation; Erwinia; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Kinetics; Molecular Sequence Data; Oxylipins; Plant Diseases; RNA, Messenger; Salicylic Acid; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Solanum tuberosum; Substrate Specificity

Salicylic acid is a messenger molecule in the activation of defense responses in plants. In this study, we isolated four cDNA clones representing salicylic acid-induced genes in Chinese cabbage (Brassica rapa subsp. pekinensis) by subtractive hybridization. Of the four clones, the BC5-2 clone encodes a putative glucosyltransferase protein. The BC5-3 clone is highly similar to an Arabidopsis gene encoding a putative metal-binding farnesylated protein. The BC6-1 clone is a chitinase gene with similarities to a rapeseed class IV chitinase. Class IV chitinases have deletions in the chitin-binding and catalytic domains and the BC6-1 chitinase has an additional deletion in the catalytic domain. The BCP8-1 clone is most homologous to an Arabidopsis gene that contains a tandem array of two thiJ-like sequences. These four cabbage genes were barely expressed in healthy leaves, but were strongly induced by salicylic acid and benzothiadiazole. Expression of the three genes represented by the BC5-2, BC5-3 and BCP8-1 clones were also induced by Pseudomonas syringae pv. tomato, a nonhost pathogen that elicits a hypersensitive response in Chinese cabbage. None of these four genes, however, was strongly induced by methyl jasmonate or by ethylene.

Topics: Acetates; Amino Acid Sequence; Brassica rapa; Chitinases; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Glycosyltransferases; Molecular Sequence Data; Oxylipins; Pseudomonas; Salicylic Acid; Sequence Alignment; Sequence Homology, Amino Acid; Thiadiazoles

Expression of NpABC1, a gene encoding a plasma membrane ATP binding cassette (ABC) transporter in Nicotiana plumbaginifolia, is induced by sclareol, an antifungal diterpene produced at the leaf surface, as well as by sclareolide, a close analog. A genomic fragment including the 1282-bp region upstream of the NpABC1 transcription start was fused to the reporter beta-glucuronidase (gus) gene and introduced into N. tabacum BY2 cells for stable transformation. A 25-fold increase in gus expression was observed when cells were treated with sclareolide and some other terpenes. The combined use of 5'-deletion promoter analysis, gel mobility shift assays, DNase I footprinting, and site-directed mutagenesis allowed us to identify three cis-elements (sclareol box 1 (SB1), SB2, and SB3) located, respectively, within nucleotides -827 to -802, -278 to -243, and -216 to -190 upstream of the NpABC1 transcription start. In vivo evaluation of these elements on sclareolide-induced expression showed that mutation of SB1 reduced expression by twofold, while that of SB2 had no effect. On the other hand, SB3 had a marked effect as it completely abolished sclareolide-mediated expression. NpABC1-gus expression was not induced by the stress signals, salicylic acid and ethylene, but was mediated, to some extent, by methyl jasmonate, which is known to promote diterpene synthesis.

Topics: Acetates; ATP-Binding Cassette Transporters; Base Sequence; Cell Line; Cyclopentanes; Deoxyribonuclease I; Diterpenes; DNA Footprinting; DNA Mutational Analysis; Electrophoretic Mobility Shift Assay; Ethylenes; Gene Expression Regulation, Plant; Glucuronidase; Molecular Sequence Data; Nicotiana; Oxylipins; Plant Proteins; Promoter Regions, Genetic; Recombinant Fusion Proteins; Regulatory Sequences, Nucleic Acid; Salicylic Acid; Sequence Deletion; Sequence Homology, Nucleic Acid

Several abiotic stresses, including ethylene, methyl jasmonate, temperature, light, and wounding, were tested for their ability to induce accumulation of phenolic compounds and antioxidant capacity in purple-flesh potatoes (cv. All Blue). Results indicated that temperature, ethylene, methyl jasmonate, and light treatments did not significantly affect the accumulation of phenolic compounds compared to control samples. Only tubers with low initial anthocyanin levels treated with methyl jasmonate showed approximately 60% anthocyanin accumulation. Wounding induced the accumulation of phenolics compounds and an increase of PAL-activity in sliced tissue compared to the control. Total phenolics increased approximately 60% with a parallel 85% increase in antioxidant capacity. These results show that selection of appropriate abiotic stresses can enhance the nutritional and functional value of potatoes.

Topics: Acetates; Antioxidants; Cyclopentanes; Ethylenes; Oxylipins; Phenols; Plant Diseases; Solanum tuberosum; Temperature

Class I chitinase (Chi9) and beta-1,3-glucanase (GluB) genes are expressed in the micropylar endosperm cap of tomato (Lycopersicon esculentum) seeds just before radicle emergence through this tissue to complete germination. In gibberellin (GA)-deficient mutant (gib-1) seeds, expression of Chi9 and GluB mRNA and protein is dependent upon GA. However, as expression occurs relatively late in the germination process, we investigated whether the genes are induced indirectly in response to tissue wounding associated with endosperm cap weakening and radicle protrusion. Wounding and methyl jasmonate (MeJA) induced Chi9 expression, whereas ethylene, abscisic acid, sodium salicylate, fusicoccin, or beta-aminobutyric acid were without effect. Chi9 expression occurred only in the micropylar tissues when seeds were exposed to MeJA or were wounded at the chalazal end of the seed. Expression of Chi9, but not GluB, mRNA was reduced in germinating seeds of the jasmonate-deficient defenseless1 tomato mutant and could be restored by MeJA treatment. Chi9 expression during germination may be associated with "wounding" from cell wall hydrolysis and weakening in the endosperm cap leading to radicle protrusion, and jasmonate is involved in the signaling pathway for this response. Among these treatments and chemicals (other than GA), only MeJA and wounding induced a low level of GluB expression in gib-1 seeds. However, MeJA, wounding, and particularly ethylene induced both genes in leaves, whereas GA induced only Chi9 in leaves. Although normally expressed simultaneously during tomato seed germination, Chi9 and GluB genes are regulated distinctly and tissue specifically by hormones and wounding.

Topics: Abscisic Acid; Acetates; Chitinases; Cyclopentanes; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Germination; Gibberellins; Glucan Endo-1,3-beta-D-Glucosidase; Oxylipins; Plant Growth Regulators; Plant Leaves; RNA, Messenger; Seeds; Solanum lycopersicum; Stress, Mechanical; Substrate Specificity

The ATP-binding cassette (ABC) transporters are encoded by large gene families in plants. Although these proteins are potentially involved in a number of diverse plant processes, currently, very little is known about their actual functions. In this paper, through a cDNA microarray screening of anonymous cDNA clones from a subtractive library, we identified an Arabidopsis gene (AtPDR12) putatively encoding a member of the pleiotropic drug resistance (PDR) subfamily of ABC transporters. AtPDR12 displayed distinct induction profiles after inoculation of plants with compatible and incompatible fungal pathogens and treatments with salicylic acid, ethylene, or methyl jasmonate. Analysis of AtPDR12 expression in a number of Arabidopsis defense signaling mutants further revealed that salicylic acid accumulation, NPR1 function, and sensitivity to jasmonates and ethylene were all required for pathogen-responsive expression of AtPDR12. Germination assays using seeds from an AtPDR12 insertion line in the presence of sclareol resulted in lower germination rates and much stronger inhibition of root elongation in the AtPDR12 insertion line than in wild-type plants. These results suggest that AtPDR12 may be functionally related to the previously identified ABC transporters SpTUR2 and NpABC1, which transport sclareol. Our data also point to a potential role for terpenoids in the Arabidopsis defensive armory.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; ATP-Binding Cassette Transporters; Cloning, Molecular; Cyclopentanes; Diterpenes; DNA, Complementary; Ethylenes; Fungi; Gene Expression Regulation, Plant; Germination; Immunity, Innate; Membrane Transport Proteins; Mutation; Oligonucleotide Array Sequence Analysis; Oxylipins; Plant Diseases; Salicylic Acid; Seeds; Sequence Analysis, DNA; Signal Transduction

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

A novel ozone-sensitive mutant was isolated from Arabidopsis T-DNA tagging lines. This mutant revealed severe foliar injury and higher ethylene emission than the wild type under ozone exposure. The ozone-induced injury and ethylene emission were suppressed by pretreatment with aminoethoxyvinyl glycine, an inhibitor of ethylene biosynthesis, both in this mutant and wild-type plants. Pretreatment with methyl-jasmonate (MeJA) at 10 micro M, however, suppressed the ozone-induced ethylene emission and foliar injury only in the wild-type plants. This mutant was less sensitive to jasmonate than the wild type, estimated by the MeJA-induced inhibition of root elongation and ozone-induced expression of AtVSP1, a jasmonate-inducible gene. Thus, this mutant was named oji1 (ozone-sensitive and jasmonate-insensitive 1). These results suggest that the ozone sensitivity of oji1 is caused by the increase in ozone-induced emission of ethylene as a result of low sensitivity to jasmonate, which plays defensive roles under stress conditions.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Chromosome Mapping; Cyclopentanes; Endopeptidases; Ethylenes; Mutation; Oxylipins; Ozone; Plant Growth Regulators; Plant Leaves; Plant Roots

Jasmonates (JAs) regulate Arabidopsis thaliana (L.) Heynh. wound and defense responses, pollen development, and stress-related growth inhibition. Significantly, each of these responses requires COI1, an F-box protein. We fused firefly luciferase as a reporter to the JA-responsive promoter for the vegetative storage protein gene (VSP) and used this to screen for mutants that failed to express luciferase in the presence of JA, isolating a mutant designated coi1-16. Comparisons with coi1-1 and jar1-1 plants indicated that coi1-16 was only slightly more sensitive to JA than coi1-1 plants. However, whilst coi1-16 plants failed to produce viable pollen at 22 degrees C, they were fertile at 16 degrees C. Therefore, unlike the other coi1 mutants, coi1-16 could be maintained as a pure line and did not require selection. We have used coi1-16 seeds to define novel interactions between JA and other hormone signalling pathways in seed germination and in the development of young seedlings.

Topics: Abscisic Acid; Acetates; Alleles; Amino Acid Substitution; Animals; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Darkness; Endopeptidases; Ethylenes; Fertility; Hypocotyl; Leucine; Mutation; Mutation, Missense; Nucleotidyltransferases; Oxylipins; Phenylalanine; Plant Growth Regulators; Plant Roots; Plant Structures; Plants, Genetically Modified; Pollen; Promoter Regions, Genetic; Repetitive Sequences, Amino Acid; Seeds; Signal Transduction; Sodium Chloride; Stress, Mechanical; Temperature; Time Factors

The endoplasmic reticulum (ER) body is a characteristic structure derived from ER and is referred to as a proteinase-sorting system that assists the plant cell under various stress conditions. Fluorescent ER bodies were observed in transgenic plants of Arabidopsis expressing green fluorescent protein fused with an ER retention signal. ER bodies were widely distributed in the epidermal cells of whole seedlings. In contrast, rosette leaves had no ER bodies. We found that wound stress induced the formation of many ER bodies in rosette leaves. ER bodies were also induced by treatment with methyl jasmonate (MeJA), a plant hormone involved in the defense against wounding and chewing by insects. The induction of ER bodies was suppressed by ethylene. An electron microscopic analysis showed that typical ER bodies were induced in the non-transgenic rosette leaves treated with MeJA. An experiment using coi1 and etr1-4 mutant plants showed that the induction of ER bodies was strictly coupled with the signal transduction of MeJA and ethylene. These results suggested that the formation of ER bodies is a novel and unique type of endomembrane system in the response of plant cells to environmental stresses. It is possible that the biological function of ER bodies is related to defense systems in higher plants.

Topics: Acetates; Adaptation, Physiological; Arabidopsis; Cyclopentanes; Endoplasmic Reticulum; Ethylenes; Gene Expression Regulation, Plant; Green Fluorescent Proteins; Luminescent Proteins; Microscopy, Electron; Mutation; Oxylipins; Plant Epidermis; Plant Growth Regulators; Plant Leaves; Plants, Genetically Modified; Recombinant Fusion Proteins; Stress, Mechanical

The 22 kDa Kunitz-type potato proteinase inhibitor (22 kDa KPPI) was induced in tubers. However, the 27 kDa protein, which is immunologically related to the 22 kDa KPPI, was induced in leaves by wounding, hormones, and environmental stresses. The leaf-specific 27 kDa protein was induced in leaves that were treated with exogenous abscisic acid (ABA), ethephon, methyl jasmonate (MeJA), and water deficit. These results indicate that the 27 kDa protein in leaves could function as a defense protein against mechanical damages by herbivorous animals and abiotic environmental stresses that could induce plant hormones.

Topics: Abscisic Acid; Acetates; Cyclopentanes; Ethylenes; Molecular Weight; Organophosphorus Compounds; Oxylipins; Peptides; Plant Growth Regulators; Plant Leaves; Plant Proteins; Solanum tuberosum; Trypsin Inhibitors; Water

Ethylene-responsive element binding factors (ERF) proteins are plant-specific transcription factors, many of which have been linked to stress responses. We have identified four Arabidopsis ERF genes whose expression was specifically induced by avirulent and virulent strains of the bacterial pathogen Pseudomonas syringae pv tomato, with overlapping but distinct induction kinetics. However, a delay in ERF mRNA accumulation after infection with the virulent strain was observed when compared with the avirulent strain. The induction of ERF gene expression in most cases preceded the mRNA accumulation of a basic chitinase gene, a potential downstream target for one or more of these ERFs. The expression of the ERF genes was examined among different Arabidopsis tissues, in response to the signaling molecules ethylene, methyl jasmonate, and salicylic acid (SA), and in Arabidopsis mutants with decreased or enhanced susceptibility to pathogens, and significant differences were observed. For example, in seedlings, some of the ERF genes were not induced by SA in the wild-type but were SA responsive in the pad4-1 mutant, suggesting that PAD4-1, which acts upstream of SA accumulation, is also involved in repressing the SA-induced expression of specific ERF genes. The four ERF proteins were shown to contain transcriptional activation domains. These results suggest that transcriptional activation cascades involving ERF proteins may be important for plant defense to pathogen attack and that some ERF family members could be involved in the cross-talk between SA- and jasmonic acid-signaling pathways.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Regulation, Plant; Kinetics; Mutation; Nuclear Proteins; Oxylipins; Phylogeny; Plant Diseases; Plant Growth Regulators; Plant Proteins; Pseudomonas; RNA, Messenger; Salicylic Acid; Signal Transduction; Stress, Mechanical; Transcription Factors; Virulence

The Arabidopsis genome contains 28 genes with sequence homology to the Arabidopsis NDR1 gene and the tobacco HIN1 gene. Expression analysis of eight of these genes identified two (NHL25 and NHL3 for NDR1/HIN1-like) that show pathogen-dependent mRNA accumulation. Transcripts did not accumulate during infection with virulent Pseudomonas syringae pv. tomato DC3000 but did accumulate specifically when the bacteria carried any of the four avirulence genes avrRpm1, avrRpt2, avrB, or avrRps4. Furthermore, expression of avrRpt2 in plants containing the corresponding resistance gene, RPS2, was sufficient to induce transcript accumulation. However, during infection with an avirulent oomycete, Peronospora parasitica isolate Cala-2, only NHL25 expression was reproducibly induced. Salicylic acid (SA) treatment can induce expression of NHL25 and NHL3. Studies performed on nahG plants showed that, during interaction with avirulent bacteria, only the expression of NHL25 but not that of NHL3 was affected. This suggests involvement of separate SA-dependent and SA-independent pathways, respectively, in the transcriptional activation of these genes. Bacteria-induced gene expression was not abolished in ethylene- (etrl-3 and ein2-1) and jasmonate- (coil-1) insensitive mutants or in mutants impaired in disease resistance (ndr1-1 and pad4-1). Interestingly, NHL3 transcripts accumulated after infiltration with the avirulent hrcC mutant of Pseudomonas syringae pv. tomato DC3000 and nonhost bacteria but not with the virulent Pseudomonas syringae pv. tomato DC3000, suggesting that virulent bacteria may suppress NHL3 expression during pathogenesis. Hence, the expression patterns and sequence homology to NDR1 and HIN1 suggest one or more potential roles for these genes in plant resistance.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Carboxylic Ester Hydrolases; Cyclopentanes; DNA-Binding Proteins; Ethylenes; Gene Expression Regulation, Plant; Immunity, Innate; Mutation; Oomycetes; Oxylipins; Plant Diseases; Plant Proteins; Pseudomonas; RNA, Messenger; Salicylic Acid; Stress, Mechanical; Transcription Factors; Virulence

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

Glutathione S-transferases (GSTs) appear to be ubiquitous in plants and have defined roles in herbicide detoxification. In contrast, little is known about their roles in normal plant physiology and during responses to biotic and abiotic stress. Forty-seven members of the GST super-family were identified in the Arabidopsis genome, grouped into four classes, with amino acid sequence identity between classes being below 25%. The two small zeta (GSTZ) and theta (GSTT) classes have related GSTs in animals while the large phi (GSTF) and tau (GSTU) classes are plant specific. As a first step to functionally characterize this diverse super-family, 10 cDNAs representing all GST classes were cloned by RT-PCR and used to study AtGST expression in response to treatment with phytohormones, herbicides, oxidative stress and inoculation with virulent and avirulent strains of the downy mildew pathogen Peronospora parasitica. The abundance of transcripts encoding AtGSTF9, AtGSTF10, AtGSTU5, AtGSTU13 and AtGSTT1 were unaffected by any of the treatments. In contrast, AtGSTF6 was upregulated by all treatments while AtGSTF2, AtGSTF8, AtGSTU19 and AtGSTZ1 each showed a selective spectrum of inducibility to the different stresses indicating that regulation of gene expression in this super-family is controlled by multiple mechanisms. The respective cDNAs were over expressed in E. coli. All GSTs except AtGSTF10 formed soluble proteins which catalysed a specific range of glutathione conjugation or glutathione peroxidase activities. Our results give further insights into the complex regulation and enzymic functions of this plant gene super-family.

Topics: 2,4-Dichlorophenoxyacetic Acid; Acetates; Amino Acid Sequence; Arabidopsis; Blotting, Northern; Cloning, Molecular; Cyclopentanes; DNA, Complementary; Escherichia coli; Ethylenes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genetic Variation; Glutathione Transferase; Hydrogen Peroxide; Isoenzymes; Molecular Sequence Data; Multigene Family; Oomycetes; Oxylipins; Phylogeny; Plant Growth Regulators; Recombinant Proteins; RNA, Messenger; Salicylic Acid; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Substrate Specificity

In Arabidopsis, the rhizobacterial strain Pseudomonas fluorescens WCS417r triggers an induced systemic resistance (ISR) response that is effective against different types of pathogens. The ISR signaling pathway functions independent of salicylic acid, but requires responsiveness to jasmonate (JA) and ethylene. Using the genetic variability of ISR inducibility between Arabidopsis accessions, we recently identified a locus (ISR1) on chromosome III that is involved in ISR signaling. Accessions RLD and Wassilewskija (Ws) are recessive at the ISR1 locus and are, therefore, unable to develop ISR. Here we investigated whether the ISR1 locus is involved in JA or ethylene signaling. Compared with the ISR-inducible accession Columbia (Col), accessions RLD and Ws were not affected in JA-induced inhibition of root growth and expression of the JA-responsive gene Atvsp, suggesting that the ISR1 locus is not involved in JA signaling. However, RLD and Ws showed an affected expression of the triple response and a reduced expression of the ethylene responsive genes Hel and Pdf1.2 after exogenous application of the ethylene precursor 1-aminocyclopropane-1-carboxylate. Moreover, in contrast to Col, RLD and Ws did not develop resistance against P. syringae pv. tomato DC3000 after treatment of the leaves with 1-aminocyclopropane-1-carboxylate. Analysis of the F(2) and F(3) progeny of a cross between Col (ISR1/ISR1) and RLD (isr1/isr1) revealed that reduced sensitivity to ethylene cosegregates with the recessive alleles of the ISR1 locus. These results suggest that the ISR1 locus encodes a component of the ethylene response, which is required for the expression of rhizobacteria-mediated ISR.

Topics: Acetates; Arabidopsis; Base Sequence; Cyclopentanes; DNA Primers; Ethylenes; Germination; Immunity, Innate; Oxylipins; Plant Growth Regulators; Plant Roots; Pseudomonas fluorescens; Signal Transduction

Senescence is a sequence of biochemical and physiological events that constitute the final stage of development. The identification of genes that alter senescence has practical value and is helpful in revealing pathways that influence senescence. However, the genetic mechanisms of senescence are largely unknown. The leaf of the oresara9 (ore9) mutant of Arabidopsis exhibits increased longevity during age-dependent natural senescence by delaying the onset of various senescence symptoms. It also displays delayed senescence symptoms during hormone-modulated senescence. Map-based cloning of ORE9 identified a 693-amino acid polypeptide containing an F-box motif and 18 leucine-rich repeats. The F-box motif of ORE9 interacts with ASK1 (Arabidopsis Skp1-like 1), a component of the plant SCF complex. These results suggest that ORE9 functions to limit leaf longevity by removing, through ubiquitin-dependent proteolysis, target proteins that are required to delay the leaf senescence program in Arabidopsis.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Base Sequence; Carrier Proteins; Cyclopentanes; DNA Primers; Ethylenes; Genes, Plant; Molecular Sequence Data; Mutation; Oxylipins; Plant Leaves; Plant Proteins; Sequence Homology, Amino Acid

Antimicrobial proteins are a key feature underlying the deployment of both pre-formed and inducible defence responses. Probably the most well characterised class are the pathogenesis-related (PR) proteins, which are found in both basic and acidic isoforms. Here we describe the isolation and characterisation of a gene, designated AtPRB1, encoding a basic PR1-like protein from Arabidopsis. This protein showed high amino acid sequence identity with basic and acidic PR1 proteins from other plant species, for example PRB1 from Nicotiana tabacum and PR1 from Brassica napus, at 64% and 78% identity respectively. A genomic DNA fragment containing 2345 bp upstream from the putative transcriptional start site was fused to the gene encoding the luciferase (LUC) gene from Photinus pyralis in order to test for promoter activity. The resulting construct was transformed into Arabidopsis accession Col-0 and analysis of LUC activity, using an ultra-low-light imaging camera system, revealed that the AtPRB1 promoter established an exquisite organ-specific expression pattern. LUC activity was observed in flowers, stems and roots but not in leaf tissue. Superimposed upon this organ-specific expression pattern was responsiveness, in root tissue, to ethylene and methyl jasmonate (MeJA), important cues during the establishment of plant disease resistance. In contrast, AtPRB1::LUC gene expression was repressed in response to salicylic acid treatment. Analysis of a limited series of AtPRB1 5'-promoter deletion mutants, identified a number of promoter regions important for both the establishment of organ-specific expression and responsiveness to ethylene and MeJA. While AtPRB1 gene expression was not induced in response to an avirulent isolate of Peronospora parasitica in leaf tissue, this gene may contribute to horizontal resistance in other tissues and/or to MeJA- and ethylene-dependent defence responses engaged against necrotrophic pathogens in root tissue. It is anticipated that transgenic plants containing AtPRB1-based promoter::reporter constructs will provide useful tools for the future dissection of the cognate signalling networks regulating the expression of this gene.

Topics: Acetates; Amino Acid Sequence; Arabidopsis; Arabidopsis Proteins; Blotting, Northern; Cloning, Molecular; Cyclopentanes; DNA, Plant; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Luciferases; Molecular Sequence Data; Oxylipins; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Recombinant Fusion Proteins; RNA, Plant; Sequence Alignment; Sequence Analysis, DNA; Sequence Deletion; Sequence Homology, Amino Acid; Tissue Distribution

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

Recognition of avirulent microbial pathogens activates an oxidative burst leading to the accumulation of reactive oxygen intermediates (ROIs), which are thought to integrate a diverse set of defence mechanisms resulting in the establishment of plant disease resistance. A novel transgenic Arabidopsis line containing a gst1:luc transgene was developed and employed to report the temporal and spatial dynamics of ROI accumulation and cognate redox signalling in response to attempted infection by avirulent strains of Pseudomonas syringae pv. tomato (Pst). Strong engagement of the oxidative burst was dependent on the presence of functional Pst hrpS and hrpA gene products. Experiments employing pharmacological agents suggested that at least two distinct sources, including an NADPH oxidase and a peroxidase-type enzyme, contributed to the generation of redox cues. The analysis of gst1 and pal1 gene expression in nahG, coi1 and etr1 plants suggested that engagement of the oxidative burst and cognate redox signalling functioned independently of salicylic acid, methyl jasmonate and ethylene. In contrast, studies using a panel of protein kinase and phosphatase inhibitors and in-gel kinase assays in these mutant backgrounds suggested that a 48 kDa mitogen-activated protein kinase (MAPK) activity was required for the activation of gst1 and pal1 in response to redox cues. Thus the engagement of a bifurcating redox signalling pathway possessing a MAPK module may contribute both to the establishment of plant disease resistance, and to the development of cellular protectant mechanisms.

Topics: Acetates; Arabidopsis; Cyclopentanes; Enzyme Inhibitors; Ethylenes; Flavonoids; Gene Expression Regulation, Plant; Genetic Markers; Glutathione Transferase; Hydrogen Peroxide; Luciferases; Microscopy, Fluorescence; Mitogen-Activated Protein Kinase Kinases; Oxidation-Reduction; Oxygen; Oxylipins; Plants, Genetically Modified; Pseudomonas; Reactive Oxygen Species; Recombinant Fusion Proteins; Salicylic Acid; Signal Transduction; Time Factors

Climacteric Fuji apples were treated with 10 microL x L(-1) MCP (1-methylcyclopropene), 2 mmol x L(-1) MJ (methyl jasmonate), or a combination of 10 microL x L(-1) MCP and 2 mmol x L(-1) MJ. Fruit were kept at 20 degrees C for 15 days after treatment. Production of ethylene and other volatile compounds was measured prior to and 3, 7, 11, and 15 days after treatment. Ethylene production decreased 3 days following MJ treatment and then increased. MCP treatment alone or in combination with MJ inhibited ethylene production. MJ and MCP inhibited production of many volatile alcohols and esters. The production of individual alcohols and esters appears to be differentially inhibited by MJ or MCP. MJ and MCP inhibited not only production of alcohols but also formation of esters from alcohols.

Topics: Acetates; Cyclopentanes; Cyclopropanes; Ethylenes; Fruit; Oxylipins; Volatilization

Harpin, the product of the hrpN gene of Erwinia amylovora, elicits the hypersensitive response and disease resistance in many plants. Harpin and known inducers of systemic acquired resistance (SAR) were tested on five genotypes of Arabidopsis thaliana to assess the role of SAR in harpin-induced resistance. In wild-type plants, harpin elicited systemic resistance to Peronospora parasitica and Pseudomonas syringae pv. tomato, accompanied by induction of the SAR genes PR-1 and PR-2. However, in experiments with transgenic Arabidopsis plants containing the nahG gene which prevents accumulation of salicylic acid (SA), harpin neither elicited resistance nor activated SAR gene expression. Harpin also failed to activate SAR when applied to nim1 (non-inducible immunity) mutants, which are defective in responding to SA and regulation of SAR. In contrast, mutants compromised in responsiveness to methyl jasmonate and ethylene developed the same resistance as did wild-type plants. Thus, harpin elicits disease resistance through the NIM1-mediated SAR signal transduction pathway in an SA-dependent fashion. The site of action of harpin in the SAR regulatory pathway is upstream of SA.

Topics: Acetates; Anti-Bacterial Agents; Arabidopsis; Bacterial Outer Membrane Proteins; Cyclopentanes; Ethylenes; Mutation; Oomycetes; Oxylipins; Plant Diseases; Plant Proteins; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Pseudomonas; Salicylic Acid; Schizosaccharomyces pombe Proteins

Inoculation of wild-type Arabidopsis plants with the fungus Alternaria brassicicola results in systemic induction of genes encoding a plant defensin (PDF1.2), a basic chitinase (PR-3), and an acidic hevein-like protein (PR-4). Pathogen-induced induction of these three genes is almost completely abolished in the ethylene-insensitive Arabidopsis mutant ein2-1. This indicates that a functional ethylene signal transduction component (EIN2) is required in this response. The ein2-1 mutants were found to be markedly more susceptible than wild-type plants to infection by two different strains of the gray mold fungus Botrytis cinerea. In contrast, no increased fungal colonization of ein2-1 mutants was observed after challenge with avirulent strains of either Peronospora parasitica or A. brassicicola. Our data support the conclusion that ethylene-controlled responses play a role in resistance of Arabidopsis to some but not all types of pathogens.

Topics: Acetates; Alternaria; Arabidopsis; Arabidopsis Proteins; Botrytis; Cyclopentanes; Ethylenes; Gene Expression Regulation, Plant; Immunity, Innate; Oxylipins; Plant Growth Regulators; Plant Proteins; Receptors, Cell Surface; Signal Transduction

Converging data indicate the possible existence of a general adaptation syndrome (GAS) in which different types of stress evoke identical coping mechanisms. In Selyean terms, this implies a "co-stress" response whereby one type of stress resistance may impart co-resistance to others. Common coping denominators may be physiological or morphological. The former include oxy-free radical scavenging, osmoregulation, ABA, jasmonates, chaperones, HSPs, and phytochelatins. Morphological GAS adaptations include leaf pubescence, movements and stance, and rooting characteristics. The feasibility, with certain reservations, of the GAS hypothesis is discussed here.

Topics: Abscisic Acid; Acetates; Adaptation, Physiological; Antioxidants; Cyclopentanes; Environmental Pollution; Ethylenes; Free Radical Scavengers; Heat-Shock Proteins; Membrane Lipids; Nitric Oxide; Oxylipins; Plants; Temperature; Ubiquitins; Water; Water-Electrolyte Balance

Plants have the ability to acquire an enhanced level of resistance to pathogen attack after being exposed to specific biotic stimuli. In Arabidopsis, nonpathogenic, root-colonizing Pseudomonas fluorescens bacteria trigger an induced systemic resistance (ISR) response against infection by the bacterial leaf pathogen P. syringae pv tomato. In contrast to classic, pathogen-induced systemic acquired resistance (SAR), this rhizobacteria-mediated ISR response is independent of salicylic acid accumulation and pathogenesis-related gene activation. Using the jasmonate response mutant jar1, the ethylene response mutant etr1, and the SAR regulatory mutant npr1, we demonstrate that signal transduction leading to P. fluorescens WCS417r-mediated ISR requires responsiveness to jasmonate and ethylene and is dependent on NPR1. Similar to P. fluorescens WCS417r, methyl jasmonate and the ethylene precursor 1-aminocyclopropane-1-carboxylate were effective in inducing resistance against P. s. tomato in salicylic acid-nonaccumulating NahG plants. Moreover, methyl jasmonate-induced protection was blocked in jar1, etr1, and npr1 plants, whereas 1-aminocyclopropane-1-carboxylate-induced protection was affected in etr1 and npr1 plants but not in jar1 plants. Hence, we postulate that rhizobacteria-mediated ISR follows a novel signaling pathway in which components from the jasmonate and ethylene response are engaged successively to trigger a defense reaction that, like SAR, is regulated by NPR1. We provide evidence that the processes downstream of NPR1 in the ISR pathway are divergent from those in the SAR pathway, indicating that NPR1 differentially regulates defense responses, depending on the signals that are elicited during induction of resistance.

Topics: Acetates; Arabidopsis; Base Sequence; Cyclopentanes; DNA Primers; DNA, Plant; Ethylenes; Genes, Plant; Mutation; Oxylipins; Plant Diseases; Plant Growth Regulators; Pseudomonas; Pseudomonas fluorescens; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction

Activation of the plant defensin gene PDF1.2 in Arabidopsis by pathogens has been shown previously to be blocked in the ethylene response mutant ein2-1 and the jasmonate response mutant coi1-1. In this work, we have further investigated the interactions between the ethylene and jasmonate signal pathways for the induction of this defense response. Inoculation of wild-type Arabidopsis plants with the fungus Alternaria brassicicola led to a marked increase in production of jasmonic acid, and this response was not blocked in the ein2-1 mutant. Likewise, A. brassicicola infection caused stimulated emission of ethylene both in wild-type plants and in coi1-1 mutants. However, treatment of either ein2-1 or coi1-1 mutants with methyl jasmonate or ethylene did not induce PDF1.2, as it did in wild-type plants. We conclude from these experiments that both the ethylene and jasmonate signaling pathways need to be triggered concomitantly, and not sequentially, to activate PDF1.2 upon pathogen infection. In support of this idea, we observed a marked synergy between ethylene and methyl jasmonate for the induction of PDF1.2 in plants grown under sterile conditions. In contrast to the clear interdependence of the ethylene and jasmonate pathways for pathogen-induced activation of PDF1.2, functional ethylene and jasmonate signaling pathways are not required for growth responses induced by jasmonate and ethylene, respectively.

Topics: Acetates; Alternaria; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Defensins; Ethylenes; Gene Expression Regulation, Plant; Genes, Plant; Models, Biological; Mutation; Oxylipins; Paraquat; Plant Growth Regulators; Plant Proteins; Signal Transduction; Superoxides

Topics: Acetates; Culture Techniques; Cyclopentanes; Ethylenes; Mitosporic Fungi; Nicotiana; Nicotine; Oxylipins; Phytoalexins; Plant Extracts; Plants, Toxic; Rhizobium; Sesquiterpenes; Terpenes