methyl-jasmonate and Disease-Resistance

Priming by natural compounds is an interesting alternative for sustainable agriculture, which also contributes to explore the molecular mechanisms associated with stress tolerance. Although hosts and stress types eventually determine the mode of action of plant-priming agents, it highlights that many of them act on redox signalling. These include vitamins thiamine, riboflavin and quercetin; organic acids like pipecolic, azelaic and hexanoic; volatile organic compounds such as methyl jasmonate; cell wall components like chitosans and oligogalacturonides; H

Topics: Acetates; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Oxidation-Reduction; Oxylipins; Plant Diseases; Plant Immunity; Plants; Volatile Organic Compounds

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

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

GhMYB4 acts as a negative regulator in lignin biosynthesis, which results in alteration of cell wall integrity and activation of cotton defense response. Verticillium wilt of cotton (Gossypium hirsutum) caused by the soil-borne fungus Verticillium dahliae (V. dahliae) represents one of the most important constraints of cotton production worldwide. Mining of the genes involved in disease resistance and illuminating the molecular mechanisms that underlie this resistance is of great importance in cotton breeding programs. Defense-induced lignification in plants is necessary for innate immunity, and there are reports of a correlation between increased lignification and disease resistance. In this study, we present an example in cotton whereby plants with reduced lignin content also exhibit enhanced disease resistance. We identified a negative regulator of lignin synthesis, in cotton encoded in GhMYB4. Overexpression of GhMYB4 in cotton and Arabidopsis enhanced resistance to V. dahliae  with reduced lignin deposition. Moreover, GhMYB4 could bind the promoters of several genes involved in lignin synthesis, such as GhC4H-1, GhC4H-2, Gh4CL-4, and GhCAD-3, and impair their expression. The reduction of lignin content in GhMYB4-overexpressing cotton led to alterations of cell wall integrity (CWI) and released more oligogalacturonides (OGs) which may act as damage-associated molecular patterns (DAMPs) to stimulate plant defense responses. In support of this hypothesis, exogenous application with polygalacturonic acid (PGA) in cotton activated biosynthesis of jasmonic acid (JA) and JA-mediated defense against V. dahliae, similar to that described for cotton plants overexpressing GhMYB4. This study provides a new candidate gene for cotton disease-resistant breeding and an increased understanding of the relationship between lignin synthesis, OG release, and plant immunity.

Topics: Acetates; Arabidopsis; Ascomycota; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Gossypium; Lignin; Oxylipins; Pectins; Phylogeny; Plant Diseases; Plant Immunity; Plant Proteins; Plants, Genetically Modified; Salicylic Acid; Transcription Factors

Topics: Abscisic Acid; Acetates; Basidiomycota; Cyclopentanes; Disease Resistance; Microscopy, Confocal; Oxylipins; Plant Diseases; Plant Leaves; Plant Roots; Reverse Transcriptase Polymerase Chain Reaction; Salicylic Acid; Triticum

In this study, we used virus-mediated gene silencing technology and found that the HSP17.4 gene-silenced cultivar Sweet Charlie plants were more susceptible to Colletotrichum gloeosporioides than the wild-type Sweet Charlie, and the level of infection was even higher than that of the susceptible cultivar Benihopp. The results of differential quantitative proteomics showed that after infection with the pathogen, the expression of the downstream response genes NPR1, TGA, and PR-1 of the salicylic acid (SA) signalling pathway was fully up-regulated in the wild-type Sweet Charlie, and the expression of the core transcription factor MYC2 of the jasmonic acid (JA) pathway was significantly down-regulated. The expression of the proteins encoded by these genes did not change significantly in the HSP17.4-silenced Sweet Charlie, indicating that the expression of HSP17.4 activated the up-regulation of downstream signals of SA and inhibited the JA signal pathway. The experiments that used SA, methyl jasmonate, and their inhibitors to treat plants provide additional evidence that the antagonism between SA and JA regulates the resistance of strawberry plants to C. gloeosporioides.

Topics: Acetates; Colletotrichum; Cyclopentanes; Disease Resistance; Fragaria; Heat-Shock Proteins; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Salicylic Acid; Signal Transduction

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

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

Pink stem borer (PSB) causes considerable yield losses to maize. Plant-insect interactions have significant implications for sustainable pest management. The present study demonstrated that PSB feeding, mechanical wounding, a combination of mechanical wounding and PSB regurgitation and exogenous application of methyl jasmonate have induced phenolic compound mediated defense responses both at short term (within 2 days of treatment) and long term (in 15 days of treatment) in leaf and stalk tissues of maize. The quantification of two major defense related phenolic compounds namely p-Coumaric acid (p-CA) and ferulic acid (FA) was carried out through ultra-fast liquid chromatography (UFLC) at 2 and 15 days after imposing the above treatments. The p-CA content induced in leaf tissues of maize genotypes were intrinsically higher when challenged by PSB attack at V3 and V6 stages in short- and long-term responses. Higher p-CA content was observed in stalk tissues upon wounding and regurgitation in short- and long-term responses at V3 and V6 stages. Significant accumulation of FA content was also observed in leaf tissues in response to PSB feeding at V3 stage in long-term response while at V6 stage it was observed both in short- and long-term responses. In stalk tissues, methyl jasmonate induced higher FA content in short-term response at V3 stage. However, at V6 stage PSB feeding induced FA accumulation in the short-term while, wounding and regurgitation treatment-induced defense responses in the long-term. In general, the resistant (DMRE 63, CM 500) and moderately resistant genotypes (WNZ ExoticPool) accumulated significantly higher contents of p-CA and FA content than susceptible ones (CM 202, BML 6) in most of the cases. The study indicates that phenolic mediated defense responses in maize are induced by PSB attack followed by wounding and regurgitation compared to the other induced treatments. Furthermore, the study confirmed that induced defense responses vary with plant genotype, stage of crop growth, plant tissue and short and long-term responses. The results of the study suggested that the Phenolic acids i.e. p-CA and FA may contribute to maize resistance mechanisms in the maize-PSB interaction system.

Topics: Acetates; Animals; Cell Wall; Chromatography, Liquid; Coumaric Acids; Cyclopentanes; Disease Resistance; Fatty Acids; Moths; Oxylipins; Plant Leaves; Zea mays

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

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

Kiwifruit (Actinidia deliciosa cv. Jinkui) were treated with 0.1 mmol/L methyl jasmonate (MeJA) to investigate the effects on disease resistance to soft rot caused by Botryosphaeria dothidea. The results showed that MeJA treatment significantly reduced the diameter of lesions after inoculation with B. dothidea. This treatment significantly enhanced the activities of related antioxidant protective enzymes, defence-related enzymes including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), polyphenol oxidase (PPO), chitinase (CHI), β-1,3 glucanase (GLU) and increased the accumulation of total phenolic content, while the degree of membrane lipid peroxidation was reduced. MeJA treatment effectively enhanced gene expression of AcPOD, AcSOD, AcCHI and AcGLU. The results from this research suggest that MeJA treatment is a promising and safe strategy for controlling postharvest rot soft of kiwifruit.

Topics: Acetates; Actinidia; Ascomycota; Chitinases; Cyclopentanes; Disease Resistance; Fruit; Gene Expression; Lipid Peroxidation; Oxylipins; Peroxidase; Phenols; Superoxide Dismutase

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

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

The mechanism of SlMYC2, involved in methyl jasmonate (MJ)-induced tomato fruit resistance to pathogens, was investigated. The data indicated that MJ treatment enhanced the accumulation of total phenolics and flavonoids, as well as individual phenolic acids and flavonoids, which might be caused by the increased phenylalanine ammonia-lyase and polyphenol oxidase activities, induced pathogenesis-related gene (PR) expression, β-1,3-glucanase and chitinase activities, as well as α-tomatine, by inducing GLYCOALKALOID METABOLISM gene expression. These effects, induced by MJ, partly contributed to tomato fruit resistance to Botrytis cinerea. Nevertheless, the induction effects of MJ were almost counteracted by silence of SlMYC2, and the disease incidence and lesion diameter in MJ + SlMYC2-silenced fruit were higher than those in MJ-treated fruit. These observations are the first evidence that SlMYC2 plays vital roles in MJ-induced fruit resistance to Botrytis cinerea, possibly by regulating defence enzyme activities, SlPRs expression, α-tomatine, special phenolic acids and flavonoid compounds.

Topics: Acetates; Botrytis; Cyclopentanes; Disease Resistance; Flavonoids; Fruit; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Oxylipins; Phenylalanine Ammonia-Lyase; Plant Diseases; Plant Proteins; Solanum lycopersicum; Tomatine

Cultivated sweet potato (

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

Ubiquitin ligase VpRH2 is a negative regulator in the grape ABA pathway by inhibiting ABL1, PYR1 and GRP2A expressions, and its promoter is inhibited by ABA treatment. In higher plants, ubiquitin ligases play key roles in various cellular processes. As in our previous study (Wang et al. in J Exp Bot 68:1669-1687, 2017), grape RING-H2-type ubiquitin ligase gene VpRH2 and its promoter was induced by powdery mildew and showed resistance to the disease. Diverse small-molecule hormones, like salicylic acid (SA), methyl jasmonate (MeJA) or abscisic acid (ABA), play pivotal roles in plant resistance. Here we found that VpRH2 expression could be induced by SA and MeJA treatment, but inhibited by ABA treatment. The promoter of VpRH2 revealed a similar variation trend under exogenous hormone treatments as the gene expression by GUS activity assay. By a series of deletion fragments, the promoter fragment of VpRH2-P656 to VpRH2-P513 was necessary in response to MeJA treatment, and the inhibition of ABA treatment to the VpRH2 promoter was independent of the ABRE motif. Over-expression of VpRH2 in Arabidopsis thaliana plants displayed ABA-insensitive phenotypes at the germination stage compared to wild type plants. In VpRH2 over-expressing Vitis vinifera cv. Thompson Seedless plants after ABA treatments, the expression of the ABA pathway related genes ABL1 and PYR1 showed a suppresive trend. Moreover, VpGRP2A (an VpRH2-interacting protein) also showed a suppresive trend in response to ABA treatment in VpRH2-overexpressing plants. Our results demonstrate that VpRH2 is a negative regulator in the grape ABA signal pathway by inhibiting ABL1, PYR1 and GRP2A expressions, and its promoter was also inhibited by ABA treatment.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Germination; Ligases; Membrane Transport Proteins; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Salicylic Acid; Ubiquitin; Vitis

The family Sclerotiniaceae includes important phytopathogens, such as

Topics: Acetates; Ascomycota; Camellia; Cyclopentanes; Disease Resistance; Flowers; Gene Expression Regulation, Plant; Oxylipins; Plant Diseases; Plant Immunity; Time Factors

The effects of postharvest methyl jasmonate (MeJA) treatment (50 μmol L. The results indicated that MeJA treatment significantly restrained the development of gray mold decay in blueberries. The treatment induced a nitric oxide (NO) burst and increased the endogenous hydrogen peroxide (H. These results suggested that MeJA could induce the disease resistance of blueberries against B. cinerea by regulating the antioxidant enzymes, defense-related enzymes, and the phenylpropanoid pathway through the activation of signaling molecules.

Topics: Acetates; Blueberry Plants; Botrytis; Cyclopentanes; Disease Resistance; Fruit; Hydrogen Peroxide; Nitric Oxide; Oxylipins; Plant Diseases; Plant Proteins

Arginase plays key roles in methyl jasmonate (MeJA)-mediated quality maintenance in vegetables and fruits. MeJA treatment induced the Arginase 2 (SlARG2) expression, which is one of the most important encoding genes of arginase. In addition, the treatment with MeJA induced resistance to pathogenic infection in many plants. However, the functions of SlARG2 in MeJA-induced defense to Botrytis cinerea are unclear. In our work, control and SlARG2-silenced tomato fruits (Solanum lycopersicum) were treated with 0.05 mmoL L. Our results indicated that MeJA treatment induced both pathogenesis-related gene expression (PR1, PR2a, PR2b and PR3b), and the activity of defense-related enzymes, as well as upregulated arginine metabolism. Compared to control fruits, the treatment with MeJA also induced the activity of arginase, arginine decarboxylase (ADC) and ornithine aminotransferase (OAT), and expression of SlARG2, SlADC, ornithine decarboxylase (SlODC) and SlOAT, and consequently increased the accumulation of arginine, proline, glutamate, putrescine and spermine. However, the induction effects by MeJA were significantly reduced in fruits in which SlARG2 was silenced and severe disease symptoms were observed.. MeJA fumigation could inhibit disease development by inducing pathogenesis-related gene expression (PR1, PR2a, PR2b and PR3b) and defense-related enzymes activity, as well as upregulated arginine metabolism. In addition, SlARG2 silencing could inhibit the functions of MeJA in inducing the accumulation of the above substances. Overall, our study provided strong evidence that SlARG2 was essential for MeJA-induced tomato fruit defense responses to Botrytis cinerea. © 2020 Society of Chemical Industry.

Topics: Acetates; Botrytis; Cyclopentanes; Disease Resistance; Fruit; Gene Expression Regulation, Plant; Humans; Oxylipins; Plant Diseases; Plant Proteins; Solanum lycopersicum

The plant hormones salicylic acid (SA) and jasmonic acid (JA) regulate defense mechanisms capable of overcoming different plant stress conditions and constitute distinct but interconnected signaling pathways. Interestingly, several other molecules are reported to trigger stress-specific defense responses to biotic and abiotic stresses. In this study, we investigated the effect of 14 elicitors against diverse but pivotal types of abiotic (drought) and biotic (the chewing insect Ascia monuste, the hemibiotrophic bacterium Pseudomonas syringae DC 3000 and the necrotrophic fungus Alternaria alternata) stresses on broccoli and Arabidopsis. Among the main findings, broccoli pre-treated with SA and chitosan showed the highest drought stress recovery in a dose-dependent manner. Several molecules led to increased drought tolerance over a period of three weeks. The enhanced drought tolerance after triggering the SA pathway was associated with stomata control. Moreover, methyl jasmonate (MeJA) reduced A. monuste insect development and plant damage, but unexpectedly, other elicitors increased both parameters. GUS reporter assays indicated expression of the SA-dependent PR1 gene in plants treated with nine elicitors, whereas the JA-dependent LOX2 gene was only expressed upon MeJA treatment. Overall, elicitors capable of tackling drought and biotrophic pathogens mainly triggered the SA pathway, but adversely also induced systemic susceptibility to chewing insects. These findings provide directions for potential future in-depth characterization and utilization of elicitors and induced resistance in plant protection.

Topics: Acetates; Alternaria; Animals; Arabidopsis; Brassica; Butterflies; Cyclopentanes; Disease Resistance; Droughts; Gene Expression Regulation, Plant; Oxylipins; Plant Diseases; Plant Proteins; Pseudomonas syringae; Salicylic Acid

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

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

Panax notoginseng is a famous Chinese herbal medicine, but the root rot disease mainly caused by Fusarium solani severely reduces the yield and quality of its medicinal materials.. The defense priming in P. notoginseng through exogenous application of signaling molecule will supply theoretical support for the exogenous regulation of disease resistance in P. notoginseng.. In this study, the exogenous application of methyl jasmonate (MeJA) increased P. notoginseng's resistance to F. solani. Furthermore, the P. notoginseng transcriptome during F. solani infection was investigated through next-generation sequencing to uncover the resistance mechanism of P. notogingseng induced by MeJA.. The de novo assembly of transcriptome sequences produced 80,551 unigenes, and 36,771 of these unigenes were annotated by at least one database. A differentially expressed gene analysis revealed that a large number of genes related to terpenoid backbone biosynthesis, phenylalanine metabolism, and plant-pathogen interactions were predominantly up-regulated by MeJA. Moreover, jasmonic acid (JA) biosynthesis-related genes and the JA signaling pathway genes, such as linoleate 13S-lipoxygenase, allene oxide cyclase, allene oxide synthase, TIFY, defensin, and pathogenesis-related proteins, showed increased transcriptional levels after inoculation with F. solani. Notably, according to the gene expression analysis, JA and ethylene signaling pathways may act synergistically to positively regulate the defense responses of P. notoginseng to F. solani.. JA signaling appears to play a vital role in P. notoginseng responses to F. solani infection, which will be helpful in improving the disease resistance of P. notoginseng cultivars as well as in developing an environmentally friendly biological control method for root rot disease.

Topics: Acetates; Cyclopentanes; Disease Resistance; Fusarium; Gene Expression Profiling; Gene Expression Regulation, Plant; Oxylipins; Panax notoginseng; Plant Diseases; RNA-Seq; Transcriptome

Grape (Vitis vinifera L.) is one of the most widely cultivated and economically important fruits. Most cultivated varieties of grape are highly susceptible to fungal diseases, and one of the most pervasive is powdery mildew, caused by Uncinula necator. The jasmonate-ZIM domain (JAZ) family proteins are critical for plant responses to environmental stresses. Here, we report the characterization of VqJAZ4, a jasmonate-ZIM domain gene isolated from Vitis quinquangularis, a Chinese wild Vitis species that exhibits high tolerance to several kinds of fungi. Subcellular localization assay indicated that the VqJAZ4 protein is targeted to the nucleus. The VqJAZ4 gene was strongly induced by U. necator inoculation, as well as by the defense-related hormones methyl jasmonate (MeJA) and salicylic acid (SA). The upregulation of VqJAZ4 after inoculation was dependent on its promoter sequences. Expression of VqJAZ4 in Arabidopsis thaliana improved resistance to powdery mildew. Histochemical staining assays indicated that plants expressing VqJAZ4 displayed a larger number of dead cells and stronger reactive oxygen species (ROS) burst than non-transgenic control (NTC) plants. Expression analysis of several disease-related genes suggested that VqJAZ4 expression enhanced defense responses though SA and/or JA signaling pathways. We also found that VqJAZ4-expressing Arabidopsis showed increased susceptibility to Botrytis cinerea. Taken together, these results provide evidence that VqJAZ4 may play an important role in response to fungal pathogens in grape, and may represent a candidate for future grape molecular breeding for disease resistance.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Botrytis; Breeding; Cyclopentanes; Disease Resistance; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Reactive Oxygen Species; Salicylic Acid; Vitis

The jasmonic acid cascade plays a pivotal role in induced plant resistance to herbivores. There have been a number of investigations into the potential uses of derivatives of this hormone for pest management. Understanding the phenotypic plasticity of plant defense traits interactions in agricultural systems may facilitate the development of novel and improved management practices, which is desirable as management of insects in most agricultural systems is currently heavily reliant on insecticides. The rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, is a pest of rice, Oryza sativa, in the southern U.S. and globally. The effects of the jasmonic acid derivative, methyl jasmonate (MJ), on induced defenses to RWW in rice, and the potential costs of MJ-induced resistance to plant growth and fitness, were tested in a series of field and greenhouse trials. It was hypothesized that seed treatments with MJ would reduce densities of larval RWW. A second hypothesis was that MJ seed treatments would alter emergence, biomass accumulation, and yield of rice. The final hypothesis was that induction of plant resistance to the RWW would diminish as the time from seed treatment increased. In order to investigate these hypotheses, RWW densities were determined in greenhouse and field trials. Plant growth was measured in the field by assessing plant emergence, root and shoot biomass, time of heading, and yield (grain mass). Results indicated that MJ seed treatments induced resistance to RWW, although this effect decayed over time. Additionally, there were costs to plant growth and fitness; emergence and heading were delayed and biomass was reduced. Importantly, however, yields on a per-plant were not significantly reduced by MJ treatment. Overall, these results are promising and show the potential for the use of jasmonate elicitors as part of a pest management program in rice.

Topics: Acetates; Animals; Cyclopentanes; Disease Resistance; Insect Control; Larva; Oryza; Oxylipins; Plant Development; Plant Diseases; Plant Growth Regulators; Seeds; Weevils

Metacaspase, as hypersensitive response (HR) executors, has been identified in many plant species. Previously, the entire gene family of metacaspase has been uncovered, but there are still questions that remain unclear regarding HR-regulating gene members. In this study, based on metacaspase expression during different grapevine genotypes interacting with Plasmopara viticola, we identified MC2 and MC5 as candidates involved in HR. We overexpressed both metacaspases as GFP fusions in tobacco BY-2 cells to address subcellular localization and cellular functions. We found MC2 located at the ER, while MC5 was nucleocytoplasmic. In these overexpressor lines, cell death elicited by the bacterial protein harpin, is significantly enhanced, indicating MC2 and MC5 mediated defence-related programmed cell death (PCD). This effect was mitigated, when the membrane-located NADPH oxidase was inhibited by the specific inhibitor diphenylene iodonium, or when cells were complemented with methyl jasmonate, a crucial signal of basal immunity. Both findings are consistent with a role of MC2 and MC5 in cell death-related immunity. Using a dual-luciferase reporter system in grapevine cells we demonstrated both MC2 and MC5 promoter alleles from V. rupestris were more responsive to harpin than those from V. vinifera cv 'Müller-Thurgau', while they were not induced by MeJA as signal linked with basal immunity. These findings support a model, where MC2 and MC5 act specifically as executors of the HR.

Topics: Acetates; Bacterial Outer Membrane Proteins; Caspases; Cell Death; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Nicotiana; Oomycetes; Oxylipins; Phylogeny; Plant Cells; Plant Diseases; Plant Immunity; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Respiratory Burst; Vitis

The plant VQ motif-containing proteins are a recently discovered class of plant regulatory proteins interacting with WRKY transcription factors capable of modulate their activity as transcriptional regulators. The short VQ motif (FxxhVQxhTG) is the main element in the WRKY-VQ interaction, whereas a newly identified variable upstream amino acid motif appears to be determinant for the WRKY specificity. The VQ family has been studied in several species and seems to play important roles in a variety of biological processes, including response to biotic and abiotic stresses. Here, we present a systematic study of the VQ family in both diploid (Fragaria vesca) and octoploid (Fragaria x ananassa) strawberry species. Thus, twenty-five VQ-encoding genes were identified and twenty-three were further confirmed by gene expression analysis in different tissues and fruit ripening stages. Their expression profiles were also studied in F. ananassa fruits affected by anthracnose, caused by the ascomycete fungus Colletotrichum, a major pathogen of strawberry, and in response to the phytohormones salicylic acid and methyl-jasmonate, which are well established as central stress signals to regulate defence responses to pathogens. This comprehensive analysis sheds light for a better understanding of putative implications of members of the VQ family in the defence mechanisms against this major pathogen in strawberry.

Topics: Acetates; Amino Acid Motifs; Colletotrichum; Cyclopentanes; Diploidy; Disease Resistance; Fragaria; Fruit; Gene Expression Profiling; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Oxylipins; Phylogeny; Plant Growth Regulators; Plant Proteins; Polyploidy; Salicylic Acid; Transcription Factors

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

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

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

Expression of the TaMDC1 in transgenic tomato plants confer resistance to bacterial and fungal pathogens, as well as an insect pest and thus prove in planta function of the wheat cystatin. Cystatins are the polypeptides with cysteine proteinase inhibitory activities. Plant cystatins or phytocystatins are known to contribute to plant resistance against insect pests. Recently, increasing data proved that some of the phytocystatins also have antifungal activities in vitro. Here, we functionally characterized a wheat multidomain cystatin, TaMDC1, using in planta assays. Expression of TaMDC1 in wheat seedlings is up-regulated in response to methyl jasmonate and salicylic acid, indicating that TaMDC1 is involved in biotic stress responses mediated by these plant hormones. The TaMDC1 cDNA was integrated in tomato genome and expressed under cauliflower mosaic virus 35S promoter. Four transgenic plants that show high level of the transgene expression were selected by RNA gel blot and immunoblot analysis and utilized to assess biotic stress resistance against the bacterial pathogen Pseudomonas syringae, the fungal pathogens Botrytis cinerea and Alternaria alternata, and the insect pest Colorado potato beetle (CPB, Leptinotarsa decemlineata). Detached leaf inoculation assays revealed that the tomato plants expressing TaMDC1 showed high levels of resistance against P. syringae and A. alternata, and elevated tolerance against B. cinerea. Sustenance of L. decemlineata larvae to the transgenic plants demonstrated inhibition of CPB larvae growth. Inhibitory activity of TaMDC1 against selected pathogens was also demonstrated by in vitro assays with total protein extracted from transgenic tomato plants. Taken together, the presented data suggest that TaMDC1 is involved in a broad spectrum biotic stress resistance in planta.

Topics: Acetates; Animals; Anti-Bacterial Agents; Antifungal Agents; Botrytis; Coleoptera; Cyclopentanes; Cystatins; Disease Resistance; Gene Expression; Larva; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Pseudomonas syringae; Salicylic Acid; Solanum lycopersicum; Triticum

Methyl jasmonate (MeJA) and ethylene play important roles in mediating defense responses against Botrytis cinerea. Ethylene response factors (ERFs) are the final components of ethylene signal transduction; whether SlERF2 participates in disease resistance against Botrytis cinerea is unclear. The objective of this study was to investigate the role of SlERF2 in MeJA-mediated defense response by using both sense and antisense SlERF2 tomato fruit. Our results showed that both MeJA treatment and pathogen infection upregulated SlERF2 expression level. Overexpression of SlERF2 enhanced tomato fruit resistance against Botrytis cinerea. MeJA treatment increased ethylene production, promoted the activities of chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase, and peroxidase, and elevated pathogenesis-related protein content and total phenolic content. Moreover, the effects of MeJA on disease response were reinforced in sense SlERF2 tomato fruit, while they were weakened in antisense SlERF2 tomato fruit. These results indicated that SlERF2 was involved in MeJA-mediated disease resistance against Botrytis cinerea in tomato fruit.

Topics: Acetates; Botrytis; Cyclopentanes; Disease Resistance; Fruit; Gene Expression Regulation, Plant; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Solanum lycopersicum; Transcription Factors

How plants defend themselves from microbial infection is one of the most critical issues for sustainable crop production. Some TGA transcription factors belonging to bZIP superfamily can regulate disease resistance through NPR1-mediated immunity mechanisms in Arabidopsis. Here, we examined biological roles of OsTGA2 (grouped into the same subclade as Arabidopsis TGAs) in bacterial leaf blight resistance. Transcriptional level of OsTGA2 was accumulated after treatment with salicylic acid, methyl jasmonate, and Xathomonas oryzae pv. Oryzae (Xoo), a bacterium causing serious blight of rice. OsTGA2 formed homo- and hetero-dimer with OsTGA3 and OsTGA5 and interacted with rice NPR1 homologs 1 (NH1) in rice. Results of quadruple 9-mer protein-binding microarray analysis indicated that OsTGA2 could bind to TGACGT DNA sequence. Overexpression of OsTGA2 increased resistance of rice to bacterial leaf blight, although overexpression of OsTGA3 resulted in disease symptoms similar to wild type plant upon Xoo infection. Overexpression of OsTGA2 enhanced the expression of defense related genes containing TGA binding cis-element in the promoter such as AP2/EREBP 129, ERD1, and HOP1. These results suggest that OsTGA2 can directly regulate the expression of defense related genes and increase the resistance of rice against bacterial leaf blight disease.

Topics: Acetates; Basic-Leucine Zipper Transcription Factors; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Oryza; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Protein Binding; Response Elements; Salicylic Acid; Xanthomonas

The homeodomain-leucine zipper (HD-ZIP) is a plant-specific transcription factor family that plays important roles in plant developmental processes in response to multiple stressors. We previously isolated a cotton HD-ZIP class I transcription factor gene,

Topics: Acetates; Botrytis; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Genes, Plant; Glucuronidase; Gossypium; Homeodomain Proteins; Oxylipins; Plant Diseases; Plants, Genetically Modified; Transcription Factors; Verticillium

SBP-box (Squamosa-promoter binding protein) genes are a type of plant-specific transcription factor and play important roles in plant growth, signal transduction and stress response. However, little is known about the SBP-box genes in pepper (

Topics: Acetates; Capsicum; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Oxylipins; Phytophthora; Plant Diseases; Plant Leaves; Plant Proteins; Plant Roots; Plants, Genetically Modified; Salicylic Acid; Transcription Factors

A pathogenesis-related gene, ScPR10 , was isolated from sugarcane and its bio-function was characterized, demonstrating that ScPR10 was involved in plant defense responses to Sporisorium scitamineum , SrMV, SA, and MeJA stresses. Plant fungal and viral diseases are the major concerns in sugarcane industry. Many anti-fungal and antivirus components, including pathogenesis-related (PR) proteins, have been identified. The pathogenesis-related protein 10 (PR10) is the dominant group in PR families, involved in the plant defense mechanism. In this study, ScPR10 (GenBank Acc. No. KT887884), a 701-bp-length PR10 gene with a 483 bp-length open reading frame, was isolated from sugarcane. Its transient expression in the leaves of Nicotiana benthamiana indicated that the function role of ScPR10 is likely in the nucleus, and it increased the level of H

Topics: Acetates; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Hydrogen Peroxide; Mosaic Viruses; Nicotiana; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Saccharum; Stress, Physiological; Ustilaginales

Homeodomain-leucine zipper class I (HD-Zip I) transcription factors have been functionally characterized in plant responses to abiotic stresses, but their roles in plant immunity are poorly understood. Here, a HD-Zip I gene, CaHZ27, was isolated from pepper (Capsicum annum) and characterized for its role in pepper immunity. Quantitative real-time polymerase chain reaction showed that CaHDZ27 was transcriptionally induced by Ralstonia solanacearum inoculation and exogenous application of methyl jasmonate, salicylic acid, or ethephon. The CaHDZ27-green fluorescent protein fused protein was targeted exclusively to the nucleus. Chromatin immunoprecipitation demonstrated that CaHDZ27 bound to the 9-bp pseudopalindromic element (CAATAATTG) and triggered β-glucuronidase expression in a CAATAATTG-dependent manner. Virus-induced gene silencing of CaHDZ27 significantly attenuated the resistance of pepper plants against R. solanacearum and downregulated defense-related marker genes, including CaHIR1, CaACO1, CaPR1, CaPR4, CaPO2, and CaBPR1. By contrast, transient overexpression of CaHDZ27 triggered strong cell death mediated by the hypersensitive response and upregulated the tested immunity-associated marker genes. Ectopic CaHDZ27 expression in tobacco enhances its resistance against R. solanacearum. These results collectively suggest that CaHDZ27 functions as a positive regulator in pepper resistance against R. solanacearum. Bimolecular fluorescence complementation and coimmunoprecipitation assays indicate that CaHDZ27 monomers bind with each other, and this binding is enhanced significantly by R. solanacearum inoculation. We speculate that homodimerization of CaHZ27 might play a role in pepper response to R. solanacearum, further direct evidence is required to confirm it.

Topics: Acetates; Amino Acid Sequence; Capsicum; Cell Death; Cell Nucleus; Cyclopentanes; Disease Resistance; DNA, Plant; Gene Expression Regulation, Plant; Gene Silencing; Homeodomain Proteins; Leucine Zippers; Luminescence; Nicotiana; Organophosphorus Compounds; Oxylipins; Plant Diseases; Plant Immunity; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Protein Binding; Protein Multimerization; Protein Transport; Ralstonia solanacearum; Salicylic Acid; Transcriptional Activation; Up-Regulation

Plant defenses often involve specialized cells and tissues. In conifers, specialized cells of the bark are important for defense against insects and pathogens. Using laser microdissection, we characterized the transcriptomes of cortical resin duct cells, phenolic cells and phloem of white spruce (Picea glauca) bark under constitutive and methyl jasmonate (MeJa)-induced conditions, and we compared these transcriptomes with the transcriptome of the bark tissue complex. Overall, ~3700 bark transcripts were differentially expressed in response to MeJa. Approximately 25% of transcripts were expressed in only one cell type, revealing cell specialization at the transcriptome level. MeJa caused cell-type-specific transcriptome responses and changed the overall patterns of cell-type-specific transcript accumulation. Comparison of transcriptomes of the conifer bark tissue complex and specialized cells resolved a masking effect inherent to transcriptome analysis of complex tissues, and showed the actual cell-type-specific transcriptome signatures. Characterization of cell-type-specific transcriptomes is critical to reveal the dynamic patterns of spatial and temporal display of constitutive and induced defense systems in a complex plant tissue or organ. This was demonstrated with the improved resolution of spatially restricted expression of sets of genes of secondary metabolism in the specialized cell types.

Topics: Acetates; Animals; Cluster Analysis; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Insecta; Laser Capture Microdissection; Organ Specificity; Oxylipins; Phloem; Picea; Plant Bark; Plant Diseases; Plant Growth Regulators; Plant Proteins; Sequence Analysis, RNA; Terpenes; Transcriptome

RNA-seq analysis on whitebark pine needles demonstrated that methyl jasmonate (MeJA)-triggered transcriptome re-programming substantially overlapped with defense responses against insects and fungal pathogens in Pinus species, increasing current knowledge regarding induced systemic resistance (ISR) to pathogens and pests in whitebark pine. Many whitebark pine populations are in steep decline due to high susceptibility to mountain pine beetle and the non-native white pine blister rust (WPBR). Resistance, including induced systemic resistance (ISR), is not well characterized in whitebark pine, narrowing the current options for increasing the success of restoration and breeding programs. Exogenous jasmonates are known to trigger ISR by activating the plant's immune system through regulation of gene expression to produce chemical defense compounds. This study reports profiles of whitebark pine needle transcriptomes, following methyl jasmonate (MeJA) treatment using RNA-seq. A MeJA-responsive transcriptome was de novo assembled and transcriptome profiling identified a set of differentially expressed genes (DEGs), revealing 1422 up- and 999 down-regulated transcripts with at least twofold change (FDR corrected p < 0.05) in needle tissues in response to MeJA application. GO analysis revealed that these DEGs have putative functions in plant defense signalling, transcription regulation, biosyntheses of secondary metabolites, and other biological processes. Lineage-specific expression of defense-related genes was characterized through comparison with MeJA signalling in model plants. In particular, MeJA-triggered transcriptome re-programming substantially overlapped with defense responses against WPBR and insects in related Pinus species, suggesting that MeJA may be used to improve whitebark pine resistance to pathogens/pests. Our study provides new insights into molecular mechanisms and metabolic pathways involved in whitebark pine ISR. DEGs identified in this study can be used as candidates to facilitate identification of genomic variation contributing to host resistance and aid in breeding selection of elite genotypes with better adaptive fitness to environmental stressors in this endangered tree species.

Topics: Acetates; Basidiomycota; Breeding; Cyclopentanes; Disease Resistance; Gene Expression Profiling; Genotype; Oxylipins; Pinus; Plant Diseases; Plant Leaves; Sequence Analysis, RNA; Transcriptome; Trees

Bacterial wilt caused by Ralstonia solanacearum is a ruinous soilborne disease affecting more than 450 plant species. Efficient control methods for this disease remain unavailable to date. This study characterized a novel nucleotide-binding site-leucine-rich repeat resistance gene AhRRS5 from peanut, which was up-regulated in both resistant and susceptible peanut cultivars in response to R. solanacearum. The product of AhRRS5 was localized in the nucleus. Furthermore, treatment with phytohormones such as salicylic acid (SA), abscisic acid (ABA), methyl jasmonate (MeJA) and ethephon (ET) increased the transcript level of AhRRS5 with diverse responses between resistant and susceptible peanuts. Abiotic stresses such as drought and cold conditions also changed AhRRS5 expression. Moreover, transient overexpression induced hypersensitive response in Nicotiana benthamiana. Overexpression of AhRRS5 significantly enhanced the resistance of heterogeneous tobacco to R. solanacearum, with diverse resistance levels in different transgenic lines. Several defence-responsive marker genes in hypersensitive response, including SA, JA and ET signals, were considerably up-regulated in the transgenic lines as compared with the wild type inoculated with R. solanacearum. Nonexpressor of pathogenesis-related gene 1 (NPR1) and non-race-specific disease resistance 1 were also up-regulated in response to the pathogen. These results indicate that AhRRS5 participates in the defence response to R. solanacearum through the crosstalk of multiple signalling pathways and the involvement of NPR1 and R gene signals for its resistance. This study may guide the resistance enhancement of peanut and other economic crops to bacterial wilt disease.

Topics: Abscisic Acid; Acetates; Arachis; Base Sequence; Cell Nucleus; Cold Temperature; Cyclopentanes; Disease Resistance; Droughts; Gene Expression Regulation, Plant; Genes, Plant; Genetic Vectors; Nicotiana; Organophosphorus Compounds; Oxylipins; Phylogeny; Plant Diseases; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Ralstonia solanacearum; Salicylic Acid; Sequence Alignment; Stress, Physiological; Transcription Factors; Up-Regulation

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

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

Plant R2R3-MYB transcription factors play crucial roles in stress responses. We previously isolated a R2R3-MYB homolog from sweet cherry cv. Hong Deng, designated PacMYBA (GenBank accession No. KF974774). To explore the role of PacMYBA in the plant stress response, we heterologously expressed PacMYBA in transgenic Arabidopsis thaliana plants. In a previous study, we demonstrated that PacMYBA is mainly localized to the nucleus and could be induced by abscisic acid (ABA). Analysis of the promoter sequence of PacMYBA revealed that it contains several stress-related cis-elements. QPCR results showed that PacMYBA is induced by salt, salicylic (SA), and jasmonic acid (JA) in sweet cherry leaves. Transgenic Arabidopsis plants heterologously expressing PacMYBA exhibited enhanced salt-tolerance and increased resistance to Pseudomonas syringe pv. tomato (Pst) DC3000 infection. Overexpression of PacMYBA decreased the osmotic potential (OP), increased the free proline content, and increased the peroxidase content in transgenic Arabidopsis plants. Furthermore, overexpression of PacMYBA also affected the expression levels of salt stress- and pathogen defense-related genes in the transgenic plants. These results indicate that PacMYBA is a positive regulator of salt stress tolerance and pathogen resistance.

Topics: Acetates; Arabidopsis; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Genes, Plant; Oxylipins; Plant Diseases; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Prunus avium; Pseudomonas; Regulatory Sequences, Nucleic Acid; Salicylic Acid; Salt Tolerance; Signal Transduction; Sodium Chloride; Stress, Physiological; Transcription Factors; Up-Regulation

CaWRKY40 is a positive regulator of pepper (Capsicum annum) response to Ralstonia solanacearum inoculation (RSI), but the underlying mechanism remains largely unknown. Here, we functionally characterize CaCDPK15 in the defense signaling mediated by CaWRKY40. Pathogen-responsive TGA, W, and ERE boxes were identified in the CaCDPK15 promoter (pCaCDPK15), and pCaCDPK15-driven GUS expression was significantly enhanced in response to RSI and exogenously applied salicylic acid, methyl jasmonate, abscisic acid, and ethephon. Virus-induced gene silencing (VIGS) of CaCDPK15 significantly increased the susceptibility of pepper to RSI and downregulated the immunity-associated markers CaNPR1, CaPR1, and CaDEF1. By contrast, transient CaCDPK15 overexpression significantly activated hypersensitive response associated cell death, upregulated the immunity-associated marker genes, upregulated CaWRKY40 expression, and enriched CaWRKY40 at the promoters of its targets genes. Although CaCDPK15 failed to interact with CaWRKY40, the direct binding of CaWRKY40 to pCaCDPK15 was detected by chromatin immunoprecipitation, which was significantly potentiated by RSI in pepper plants. These combined results suggest that RSI in pepper induces CaCDPK15 and indirectly activates downstream CaWRKY40, which in turn potentiates CaCDPK15 expression. This positive-feedback loop would amplify defense signaling against RSI and efficiently activate strong plant immunity.

Topics: Abscisic Acid; Acetates; Capsicum; Cell Death; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Gene Silencing; Hydrogen Peroxide; Organophosphorus Compounds; Oxylipins; Plant Diseases; Plant Growth Regulators; Promoter Regions, Genetic; Protein Binding; Protein Kinases; Ralstonia solanacearum; Salicylic Acid; Signal Transduction; Transcription Factors

Plant often responds to fungal pathogens by expressing a group of proteins known as pathogenesis-related proteins (PRs). The expression of PR is mediated through pathogen-induced signal-transduction pathways that are fine-tuned by phytohormones such as methyl jasmonate (MeJA). Here, we report functional characterization of an Ocimum basilicum PR5 family member (ObTLP1) that was identified from a MeJA-responsive expression sequence tag collection. ObTLP1 encodes a 226 amino acid polypeptide that showed sequence and structural similarities with a sweet-tasting protein thaumatin of Thaumatococcus danielli and also with a stress-responsive protein osmotin of Nicotiana tabacum. The expression of ObTLP1 in O. basilicum was found to be organ-preferential under unstressed condition, and responsive to biotic and abiotic stresses, and multiple phytohormone elicitations. Bacterially-expressed recombinant ObTLP1 inhibited mycelial growth of the phytopathogenic fungi, Scleretonia sclerotiorum and Botrytis cinerea; thereby, suggesting its antifungal activity. Ectopic expression of ObTLP1 in Arabidopsis led to enhanced tolerance to S. sclerotiorum and B. cinerea infections, and also to dehydration and salt stress. Moreover, induced expression of the defense marker genes suggested up-regulation of the defense-response pathways in ObTLP1-expressing Arabidopsis upon fungal challenge. Thus, ObTLP1 might be useful for providing tolerance to the fungal pathogens and abiotic stresses in crops.

Topics: Acetates; Arabidopsis; Cyclopentanes; Disease Resistance; Fungi; Ocimum basilicum; Oxylipins; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Stress, Physiological

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

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

This study was conducted to characterize the forms of disease resistance induced by methyl jasmonate (MeJA) in harvested grape berries and to evaluate the impact of the induced resistance on fruit quality. The results showed that MeJA treatment at concentrations from 10 to 100μmol/L could effectively induce disease resistance against Botrytis cinerea and reduce disease incidence in grape berries. The induced disease resistance was tightly associated with increased H2O2 generation, enhanced expression of the defense-related gene VvNPR1.1 and accumulation of stilbene phytoalexins such as tran-resveratrol and its oligomer (trans-)ε-viniferin. The expression of the defense-related gene and synthesis of phytoalexins in 10μmol/L MeJA-treated grape berries were only significantly enhanced upon inoculating the berries with B. cinerea, whereas the 50 or 100μmol/L of MeJA treatment directly induced these defense responses. Hence, we deduce that the low concentration of MeJA (10μmol/L) triggered a priming defense mechanism, while higher concentrations of MeJA (50 or 100μmol/L) directly activated defense responses, thus enhancing disease resistance in grape berries. Moreover, the primed grape berries maintained higher contents of soluble sugars and higher DPPH radical scavenging activity and reducing power compared with those expressing direct defense responses. These results indicate that priming of defense is a cost-effective strategy to protect harvested grape berries from B. cinerea infection in terms of minimizing quality loss.

Topics: Acetates; Benzofurans; Botrytis; Cyclopentanes; Disease Resistance; Fruit; Gene Expression Regulation; Hydrogen Peroxide; Oxylipins; Plant Growth Regulators; Resveratrol; Stilbenes; Vitis

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

Methyl jasmonate (MeJA) was tested by seed treatment for its ability to protect tomato seedlings against fusarium wilt caused by the soil-borne fungal pathogen Fusarium oxysporum f.sp. lycopersici. Isolated from Solanum lycopersicon L. seeds, cv. Beta fungus was identified as F. oxysporum f.sp. lycopersici Race 3 fungus by using phytopathological and molecular methods. MeJA applied at 0.01, 0.1 and 1 mM reduced spore germination and mycelial growth in vitro. Soaking of tomato seeds in MeJA solution at 0.1 mM for 1 h significantly enhanced the resistance level against the tested fungus in tomato seedlings 4 weeks after inoculation. The extracts from leaves of 15-day-old seedlings obtained from previously MeJA soaked seeds had the ability to inhibit in vitro spore germination of tested fungus. In these seedlings a significant increase in the levels phenolic compounds such as salicylic acid (SA), kaempferol and quercetin was observed. Up-regulation of phenylalanine ammonia-lyase (PAL5) and benzoic acid/salicylic acid carboxyl methyltransferase (BSMT) genes and down-regulation of the isochorysmate synthase (ICS) gene in response to exogenous MeJA application indicate that the phenylalanine ammonia-lyase (PAL), not the isochorismate (IC) pathway, is the primary route for SA production in tomato. Moreover, the increased accumulation of the flavonols quercetin and kaempferol appears closely related to the increase of PAL5, chalcone synthase (CHS) and flavonol synthase/flavanone 3-hydroxylase-like (FLS) genes. Elevated levels of salicylic acid in seedlings raised from MeJA-soaked seeds were simultaneously accompanied by a decrease of jasmonic acid, the precursor of MeJA, and an increase of 12-oxo-phytodienoic acid (OPDA), the precursor of jasmonic acid. The present results indicate that the priming of tomato seeds with 0.1mM MeJA before sowing enables the seedlings grown from these seeds to reduce the attack of the soil-borne fungal pathogen F. oxysporum f.sp. lycopersici, so it can be applied in practice.

Topics: Acetates; Biosynthetic Pathways; Cyclopentanes; Disease Resistance; Fatty Acids, Unsaturated; Flavonols; Fusarium; Gene Expression Regulation, Plant; Genes, Plant; Oxylipins; Phenols; Plant Diseases; Plant Extracts; Plant Leaves; Salicylic Acid; Seedlings; Seeds; Solanum lycopersicum; Spores, Fungal

Cystathionine β-synthase (CBS) domain containing proteins (CDCPs) constitute a big family in plants and some members in this family have been implicated in a variety of biological processes, but the precise functions and the underlying mechanism of the majority of this family in plant immunity remain to be elucidated. In the present study, a CBS domain containing protein gene, OsCBSX3, is functionally characterized in rice resistance against Magnaporthe oryzae (M. oryzae). By quantitative real-time PCR, transcripts of OsCBSX3 are up-regulated significantly by inoculation of M. oryzae and the exogenously applied salicylic acid (SA) and methyl jasmonate (MeJA). OsCBSX3 is exclusively localized to the plasma membrane by transient expression of OsCBSX3 fused to green fluorescent protein (GFP) through approach of Agrobacterium infiltration in Nicotiana benthamiana leaves. The plants of homozygous T3 transgenic rice lines of over-expressing OsCBSX3 exhibit significant enhanced resistance to M. oryzae inoculation, manifested by decreased disease symptoms, and inhibition of pathogen growth detected in DNA. Consistently, the over-expression of OsCBSX3 enhances the transcript levels of immunity associated marker genes including PR1a, PR1b, PR5, AOS2, PAL, NH1, and OsWRKY13 in plants inoculated with M. oryzae. These results suggest that OsCBSX3 acts as a positive regulator in resistance of rice to M. oryzae regulated by SA and JA-mediated signaling pathways synergistically.

Topics: Acetates; Amino Acid Sequence; Cell Membrane; Cyclopentanes; Cystathionine beta-Synthase; Disease Resistance; Gene Expression Regulation, Plant; Magnaporthe; Molecular Sequence Data; Nicotiana; Oryza; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Proteins; Plants, Genetically Modified; Real-Time Polymerase Chain Reaction; Salicylic Acid; Sequence Alignment; Signal Transduction

The evolutionarily conserved Elongator complex functions in diverse biological processes including salicylic acid-mediated immune response. However, how Elongator functions in jasmonic acid (JA)/ethylene (ET)-mediated defense is unknown. Here, we show that Elongator is required for full induction of the JA/ET defense pathway marker gene PLANT DEFENSIN1.2 (PDF1.2) and for resistance to the necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola. A loss-of-function mutation in the Arabidopsis Elongator subunit 2 (ELP2) alters B. cinerea-induced transcriptome reprogramming. Interestingly, in elp2, expression of WRKY33, OCTADECANOID-RESPONSIVE ARABIDOPSIS AP2/ERF59 (ORA59), and PDF1.2 is inhibited, whereas transcription of MYC2 and its target genes is enhanced. However, overexpression of WRKY33 or ORA59 and mutation of MYC2 fail to restore PDF1.2 expression and B. cinerea resistance in elp2, suggesting that ELP2 is required for induction of not only WRKY33 and ORA59 but also PDF1.2. Moreover, elp2 is as susceptible as coronatine-insensitive1 (coi1) and ethylene-insensitive2 (ein2) to B. cinerea, indicating that ELP2 is an important player in B. cinerea resistance. Further analysis of the lesion sizes on the double mutants elp2 coi1 and elp2 ein2 and the corresponding single mutants revealed that the function of ELP2 overlaps with COI1 and is additive to EIN2 for B. cinerea resistance. Finally, basal histone acetylation levels in the coding regions of WRKY33, ORA59, and PDF1.2 are reduced in elp2 and a functional ELP2-GFP fusion protein binds to the chromatin of these genes, suggesting that constitutive ELP2-mediated histone acetylation may be required for full activation of the WRKY33/ORA59/PDF1.2 transcriptional cascade.

Topics: Acetates; Alternaria; Arabidopsis; Arabidopsis Proteins; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Botrytis; Chromatin; Cyclopentanes; Defensins; Disease Resistance; Gene Expression Regulation, Plant; Green Fluorescent Proteins; Histone Acetyltransferases; Mutation; Oxylipins; Plant Diseases; Plants, Genetically Modified; Receptors, Cell Surface; Transcription Factors

WRKY proteins are encoded by a large gene family and are linked to many biological processes across a range of plant species. The functions and underlying mechanisms of WRKY proteins have been investigated primarily in model plants such as Arabidopsis and rice. The roles of these transcription factors in non-model plants, including pepper and other Solanaceae, are poorly understood. Here, we characterize the expression and function of a subgroup IIe WRKY protein from pepper (Capsicum annuum), denoted as CaWRKY27. The protein localized to nuclei and activated the transcription of a reporter GUS gene construct driven by the 35S promoter that contained two copies of the W-box in its proximal upstream region. Inoculation of pepper cultivars with Ralstonia solanacearum induced the expression of CaWRKY27 transcript in 76a, a bacterial wilt-resistant pepper cultivar, whereas it downregulated the expression of CaWRKY27 transcript in Gui-1-3, a bacterial wilt-susceptible pepper cultivar. CaWRKY27 transcript levels were also increased by treatments with salicylic acid (SA), methyl jasmonate (MeJA) and ethephon (ETH). Transgenic tobacco plants overexpressing CaWRKY27 exhibited resistance to R. solanacearum infection compared to that of wild-type plants. This resistance was coupled with increased transcript levels in a number of marker genes, including hypersensitive response genes, and SA-, JA- and ET-associated genes. By contrast, virus-induced gene silencing (VIGS) of CaWRKY27 increased the susceptibility of pepper plants to R. solanacearum infection. These results suggest that CaWRKY27 acts as a positive regulator in tobacco resistance responses to R. solanacearum infection through modulation of SA-, JA- and ET-mediated signaling pathways.

Topics: Acetates; Capsicum; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Gene Silencing; Host-Pathogen Interactions; Nicotiana; Organophosphorus Compounds; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Ralstonia solanacearum; Reverse Transcriptase Polymerase Chain Reaction; Salicylic Acid; Time Factors; Transcription Factors

The effect of methyl jasmonate (MeJA) on changes in polyamines content and energy status and their relation to disease resistance was investigated. Freshly harvested loquat fruit were treated with 10 μmol l(-1) MeJA and wound inoculated with Colletotrichum acutatum spore suspension (1.0 × 10(5) spores ml(-1)) after 24h, and then stored at 20 °C for 6 days. MeJA treatment significantly reduced decay incidence. MeJA treated fruit manifested higher contents of polyamines (putrescine, spermidine and spermine) compared with the control fruit, during storage. MeJA treatment also maintained higher levels of adenosine triphosphate, and suppressed an increase in adenosine monophosphate content in loquat fruit. These results suggest that MeJA treatment may inhibit anthracnose rot by increasing polyamine content and maintaining the energy status.

Topics: Acetates; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Colletotrichum; Cyclopentanes; Disease Resistance; Eriobotrya; Food Microbiology; Fruit; Oxylipins; Plant Growth Regulators; Putrescine; Spermidine; Spermine

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

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

Jasmonate is an important endogenous chemical signal that plays a role in modulation of plant defense responses. To understand its mechanisms in regulation of rice resistance against the fungal pathogen Magnaporthe oryzae, comparative phenotype and proteomic analyses were undertaken using two near-isogenic cultivars with different levels of disease resistance. Methyl-jasmonate (MeJA) treatment significantly enhanced the resistance against M. oryzae in both cultivars but the treated resistant cultivar maintained a higher level of resistance than the same treated susceptible cultivars. Proteomic analysis revealed 26 and 16 MeJA-modulated proteins in resistant and susceptible cultivars, respectively, and both cultivars shared a common set of 13 proteins. Cumulatively, a total of 29 unique MeJA-influenced proteins were identified with many of them known to be associated with plant defense response and ROS accumulation. Consistent with the findings of proteomic analysis, MeJA treatment increased ROS accumulation in both cultivars with the resistant cultivar showing higher levels of ROS production and cell membrane damage than the susceptible cultivar. Taken together, our data add a new insight into the mechanisms of overall MeJA-induced rice defense response and provide a molecular basis of using MeJA to enhance fungal disease resistance in resistant and susceptible rice cultivars.

Topics: Acetates; Cell Death; Cyclopentanes; Disease Resistance; Magnaporthe; Oryza; Oxylipins; Plant Diseases; Plant Leaves; Plant Proteins; Proteome; Proteomics; Reactive Oxygen Species

Plant ferredoxin-like protein (PFLP) is a photosynthesis-type ferredoxin (Fd) found in sweet pepper. It contains an iron-sulphur cluster that receives and delivers electrons between enzymes involved in many fundamental metabolic processes. It has been demonstrated that transgenic plants overexpressing PFLP show a high resistance to many bacterial pathogens, although the mechanism remains unclear. In this investigation, the PFLP gene was transferred into Arabidopsis and its defective derivatives, such as npr1 (nonexpresser of pathogenesis-related gene 1) and eds1 (enhanced disease susceptibility 1) mutants and NAHG-transgenic plants. These transgenic plants were then infected with the soft-rot bacterial pathogen Pectobacterium carotovorum subsp. carotovorum (Erwinia carotovora ssp. carotovora, ECC) to investigate the mechanism behind PFLP-mediated resistance. The results revealed that, instead of showing soft-rot symptoms, ECC activated hypersensitive response (HR)-associated events, such as the accumulation of hydrogen peroxide (H2 O2 ), electrical conductivity leakage and expression of the HR marker genes (ATHSR2 and ATHSR3) in PFLP-transgenic Arabidopsis. This PFLP-mediated resistance could be abolished by inhibitors, such as diphenylene iodonium (DPI), 1-l-trans-epoxysuccinyl-leucylamido-(4-guanidino)-butane (E64) and benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk), but not by myriocin and fumonisin. The PFLP-transgenic plants were resistant to ECC, but not to its harpin mutant strain ECCAC5082. In the npr1 mutant and NAHG-transgenic Arabidopsis, but not in the eds1 mutant, overexpression of the PFLP gene increased resistance to ECC. Based on these results, we suggest that transgenic Arabidopsis contains high levels of ectopic PFLP; this may lead to the recognition of the harpin and to the activation of the HR and other resistance mechanisms, and is dependent on the protease-mediated pathway.

Topics: Acetates; Arabidopsis; Bacterial Proteins; Capsicum; Cyclopentanes; Disease Resistance; Ferredoxins; Mutation; Oxylipins; Pectobacterium carotovorum; Peptide Hydrolases; Plants, Genetically Modified; Salicylic Acid

The emerald ash borer (EAB; Agrilus planipennis Fairmaire) is causing widespread mortality of ash (Fraxinus spp.) in North America. To date, no mechanisms of host resistance have been identified against this pest. Methyl jasmonate was applied to susceptible North American and resistant Asian ash species to determine if it can elicit induced responses in bark that enhance resistance to EAB. In particular, phenolic compounds, lignin, and defense-related proteins were quantified, and compounds associated with resistance were subsequently tested directly against EAB larvae in bioassays with artificial diet. MeJA application decreased adult emergence in susceptible ash species, comparable to levels achieved by insecticide application. Concentration of the phenolic compound verbascoside sharply increased after MeJA application to green and white ash. When incorporated in an artificial diet, verbascoside decreased survival and growth of EAB neonates in a dose-dependent fashion. Lignin and trypsin inhibitors were also induced by MeJA, and analogs of both compounds reduced growth of EAB larvae in artificial diets. We conclude that the application of MeJA prior to EAB attack has the ability to enhance resistance of susceptible ash trees by inducing endogenous plant defenses, and report evidence that induction of verbascoside is a mechanism of resistance to EAB.

Topics: Acetates; Adaptation, Physiological; Animals; Coleoptera; Cyclopentanes; Disease Resistance; Fraxinus; Glucosides; Insecticides; Larva; Lignin; North America; Oxylipins; Phenols; Plant Growth Regulators; Species Specificity; Trypsin Inhibitors

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

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

Many important cell-to-cell communication events in multicellular organisms are mediated by peptides, but only a few peptides have been identified in plants. In an attempt to address the difficulties in identifying plant signaling peptides, we developed a novel peptidomics approach and used this approach to discover defense signaling peptides in plants. In addition to the canonical peptide systemin, several novel peptides were confidently identified in tomato (Solanum lycopersicum) and quantified to be induced by both wounding and methyl jasmonate (MeJA). A wounding or wounding plus MeJA-induced peptide derived from the pathogenesis-related protein 1 (PR-1) family was found to induce significant antipathogen and minor antiherbivore responses in tomato. This study highlights a role for PR-1 in immune signaling and suggests the potential application of plant endogenous peptides in efforts to defeat biological threats in crop production. As PR-1 is highly conserved across many organisms and the putative peptide from At-PR1 was also found to be bioactive in Arabidopsis thaliana, our results suggest that this peptide may be useful for enhancing resistance to stress in other plant species.

Topics: Acetates; Amino Acid Sequence; Chromatography, Liquid; Cyclopentanes; Disease Resistance; Host-Pathogen Interactions; Molecular Sequence Data; Oligonucleotide Array Sequence Analysis; Oxylipins; Peptides; Plant Diseases; Plant Growth Regulators; Plant Leaves; Plant Proteins; Proteome; Proteomics; Pseudomonas syringae; Reverse Transcriptase Polymerase Chain Reaction; Solanum lycopersicum; Stress, Mechanical; Tandem Mass Spectrometry; Transcriptome

Plant receptor-like protein kinases are thought to be involved in various cellular processes mediated by signal transduction pathways. There are about 45 lectin receptor kinases in Arabidopsis, but only a few have been studied. Here, we investigated the effect of the disruption and overexpression of a plasma membrane-localized L-type lectin-like protein kinase 1, AtLPK1 (At4g02410), on plant responses to abiotic and biotic stress. Expression of AtLPK1 was strongly induced by abscisic acid, methyl jasmonate, salicylic acid and stress treatments. Overexpression of AtLPK1 in Arabidopsis resulted in enhanced seed germination and cotyledon greening under high salinity condition, while antisense transgenic lines were more sensitive to salt stress. Activity of three abiotic stress responsive genes, RD29A, RD29B and COR15A, was elevated in AtLPK1-overexpressing plants than that in wild type (WT) plants with salt treatment, whereas the transcript level of these genes in antisense plants decreased compared with WT. Furthermore, AtLPK1-overexpressing plants displayed increased resistance to infection by Botrytis cinerea and exhibited stronger expression of a group of defense-related genes than did WT. The data implicates AtLPK1 plays essential roles at both abiotic and biotic stress response in Arabidopsis thaliana.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Botrytis; Cotyledon; Cyclopentanes; Disease Resistance; Droughts; Gene Expression; Gene Expression Regulation, Plant; Germination; Mutation; Oxylipins; Plant Diseases; Plant Growth Regulators; Plants, Genetically Modified; Protein Kinases; Recombinant Fusion Proteins; Salicylic Acid; Salinity; Seeds; Sodium Chloride; Stress, Physiological

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

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

Using rapid amplification of cDNA ends, a full-length cDNA sequence of a GDP-L-galactose phosphorylase-like gene was isolated from leaves infected by Erysiphe necator in the Chinese wild (Vitis pseudoreticulata) clone, 'Baihe-35-1', an E. necator-resistant genotype. The full-length cDNA, designated as VpVTC, comprised 1943 bp and putatively encodes a 453-amino acid polypeptide containing an HIT motif. The deduced amino acid sequence showed high similarity with that of VTC genes from other plants. The expression of VpVTC, determined by reverse transcriptase-polymerase chain reaction, was induced by E. necator and defense signaling molecules, including salicylic acid, methyl jasmonate, and ethephon, in 'Baihe-35-1', the V. quinquangularis genotype 'Shang-24', and the E. necator-susceptible V. pseudoreticulata genotype, 'Hunan-1'. Transcript levels of VpVTC correlated well with the degree of disease resistance in the 3 genotypes. Maximum induction of VpVTC by E. necator (>7-fold at 96 h post-inoculation) occurred in 'Baihe-35-1', which also showed the fastest response to signaling molecules. Upregulating the expression of VpVTC in 'Baihe-35-1' resulted in a gradual increase in the ascorbic acid concentration of leaves inoculated with E. necator. Furthermore, VpVTC was expressed in leaves, stems, inflorescence, tendrils, and fruit at all developmental stages, with the highest level occurring in fruit 35 days after flowering.

Topics: Acetates; Ascomycota; Base Sequence; China; Cloning, Molecular; Cyclopentanes; Disease Resistance; DNA, Plant; Gene Expression Regulation, Plant; Genes, Plant; Genotype; Molecular Sequence Data; Oxylipins; Plant Diseases; Plant Leaves; Plant Proteins; Salicylic Acid; Sequence Alignment; Sequence Analysis, DNA; Vitis

RING-finger proteins (RFP) function as ubiquitin ligases and play key roles in plant responses to biotic and abiotic stresses. However, little information is available on the regulation of RFP expression. Here, we isolate and characterize the RFP promoter sequence from the disease-resistant Chinese wild grape Vitis pseudoreticulata accession Baihe-35-1. Promoter-GUS fusion assays revealed that defense signaling molecules, powdery mildew infection, and heat stress induce VpRFP1 promoter activity. By contrast, the RFP1 promoter isolated from Vitis vinifera was only slightly induced by pathogen infection and heat treatment. By promoter deletion analysis, we found that the -148 bp region of the VpRFP1 promoter was the core functional promoter region. We also found that, in Arabidopsis, VpRFP1 expressed under its own promoter activated defense-related gene expression and improved disease resistance, but the same construct using the VvRFP1 promoter slightly improve disease resistance. Our results demonstrated that the -148 bp region of the VpRFP1 promoter plays a key role in response to pathogen and heat stress, and suggested that expression differences between VpRFP1 and VvRFP1 may be key for the differing disease resistance phenotypes of the two Vitis genotypes.

Topics: Acetates; Ascomycota; Base Sequence; Cyclopentanes; Disease Resistance; Fluorometry; Gene Expression Regulation, Plant; Glucuronidase; Host-Pathogen Interactions; Hot Temperature; Molecular Sequence Data; Oxylipins; Plant Diseases; Plant Growth Regulators; Plant Proteins; Plants, Genetically Modified; Promoter Regions, Genetic; Regulatory Sequences, Nucleic Acid; Salicylic Acid; Sequence Homology, Nucleic Acid; Species Specificity; Stress, Physiological; Ubiquitin-Protein Ligases; Vitis

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

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

Pathogenesis-related protein-4 (PR-4) family is a group of proteins with a Barwin domain in C-terminus and generally thought to be involved in plant defense responses. However, their detailed roles are poorly understood in defense of apple plant against pathogenic infection. In the present study, a new PR-4 gene (designated as MdPR-4) was identified from Malus domestica, and its roles in defense responses of apple were investigated. The open reading frame of MdPR-4 gene is of 447 bp encoding a protein of 148 amino acids with a Barwin domain in C-terminus and a signal peptide of 26 amino acids in N-terminus. Sequence and structural analysis indicated that MdPR-4 protein belongs to class II of PR-4 family. The high-level expression of MdPR-4 was observed in flowers and leaves as revealed by quantitative real time PCR. The temporal expression analysis demonstrated that MdPR-4 expression could be up-regulated by Botryosphaeria dothidea infection and salicylic acid (SA) or methyl jasmonate (MeJA) treatment, but suppressed by diethyldithiocarbamic acid (DIECA). In vitro assays, recombinant MdPR-4 protein exhibited ribonuclease activity specific for single strand RNA and significant inhibition to hyphal growth of three apple pathogenic fungi B. dothidea, Valsa ceratosperma and Glomerella cingulata. Moreover, the inhibition was reduced by the presence of 5'-ADP. Taken all together, the results indicate that MdPR-4 protein is involved in the defense responses of apple against pathogenic attack by directly inhibiting hyphal growth, and the inhibition is correlated with its ribonuclease activity, where as MdPR-4 expression is regulated by both SA and JA signaling pathway.

Topics: Acetates; Ascomycota; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Hyphae; Malus; Oxylipins; Plant Diseases; Plant Proteins; Salicylic Acid; Signal Transduction

Plant resistance (R) gene-mediated defense responses against biotic stresses include vast transcriptional reprogramming. In several plant-pathogen systems, members of the WRKY family of transcription factors have been demonstrated to act as both positive and negative regulators of plant defense transcriptional networks. To identify the possible roles of tomato (Solanum lycopersicum) WRKY transcription factors in defense mediated by the R gene Mi-1 against potato aphid, Macrosiphum euphorbiae, and root-knot nematode (RKN), Meloidogyne javanica, we used tobacco rattle virus (TRV)-based virus-induced gene silencing and transcriptionally suppressed SlWRKY70, a tomato ortholog of the Arabidopsis thaliana WRKY70 gene. Silencing SlWRKY70 attenuated Mi-1-mediated resistance against both potato aphid and RKN showing that SlWRKY70 is required for Mi-1 function. Furthermore, we found SlWRKY70 transcripts to be inducible in response to aphid infestation and RKN inoculation. Mi-1-mediated recognition of these pests modulates this transcriptional response. As previously described for AtWRKY70, we found SlWRKY70 transcript levels to be up-regulated by salicylic acid and suppressed by methyl jasmonate. This indicates that some aspects of WRKY70 regulation are conserved among distantly related eudicots.

Topics: Acetates; Agrobacterium tumefaciens; Amino Acid Sequence; Animals; Aphids; Cyclopentanes; Disease Resistance; Gene Expression Profiling; Gene Expression Regulation, Plant; Gene Silencing; Genes, Plant; Genetic Vectors; Molecular Sequence Data; Oxylipins; Plant Diseases; Plant Leaves; Plant Proteins; Plant Roots; RNA, Plant; Salicylic Acid; Solanum lycopersicum; Transcription Factors; Transcription, Genetic; Tylenchoidea

Most commercially grown apple cultivars are susceptible to fungal diseases. Malus hupehensis has high resistance to many diseases affecting apple cultivars. Understanding innate defence mechanisms would help to develop disease-resistant apple crops. Non-expressor of pathogenesis-related genes 1 (NPR1) plays a key role in regulating salicylic acid (SA)-mediated systemic acquired resistance (SAR). MhNPR1 cDNA, corresponding to genomic DNA and its 5' flanking sequences, was isolated from M. hupehensis. Sequence analysis showed that the regulatory mechanism for oligomer-monomer transition of the MhNPR1 protein in apple might be similar to that of GmNPR1 in soybean, but different from that of AtNPR1 in Arabidopsis. No significant differences in MhNPR1 expression were found in M. hupehensis after infection with Botryosphaeria berengeriana, showing that MhNPR1 might be regulated by pathogens at the protein level, as described for Arabidopsis and grapevine. SA treatment significantly induced MhNPR1 expression in leaves, stems and roots, while methyl jasmonate (MeJA) treatment induced MhNPR1 expression in roots, but not in leaves or stems. The expression of MhNPR1 was highly increased in roots, moderately in leaves, and did not change in stems after treatment with 1-aminocyclopropane-1-carboxylic acid (ACC). SAR marker genes (MhPR1 and MhPR5) were induced by SA, MeJA and ACC in leaves, stems and roots. Overexpression of MhNPR1 significantly induced the expression of pathogenesis-related genes (NtPR1, NtPR3 and NtPR5) in transgenic tobacco plants and resistance to the fungus Botrytis cinerea, suggesting that MhNPR1 orthologues are a component of the SA defence signalling pathway and SAR is induced in M. hupehensis.

Topics: Acetates; Amino Acids, Cyclic; Botrytis; Cloning, Molecular; Cyclopentanes; Disease Resistance; DNA, Plant; Gene Expression Regulation, Plant; Malus; Nicotiana; Oxylipins; Plant Diseases; Plant Proteins; Plants, Genetically Modified; Salicylic Acid; Sequence Analysis, DNA

'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

Interaction between the coiled-coil domain of rice blast resistance protein Pi36 and methyl-jasmonate (MeJA) was studied by fluorescence and UV-vis spectroscopic techniques. The quenching mechanism of fluorescence of MeJA by this domain was discussed to be a static quenching procedure. Fluorescence quenching was explored to measure the number of binding sites n and apparent binding constants K. The thermodynamics parameters ΔH, ΔG, ΔS were also calculated. The results indicate the binding reaction was not entropy-driven but enthalpy-driven, and hydrophobic binding played major role in the interaction. The binding sites of MeJA with the coiled-coil structural domain of rice blast resistance protein Pi36 were found to approach the microenvironment of both Tyr and Trp by the synchronous fluorescence spectrometry. The distance r between donor (the coiled-coil domain of rice blast resistance protein Pi36) and acceptor (MeJA) was obtained according to Förster theory of non-radioactive energy transfer.

Topics: Absorption; Acetates; Binding Sites; Cyclopentanes; Disease Resistance; Kinetics; Magnaporthe; Oryza; Oxylipins; Plant Diseases; Plant Proteins; Protein Structure, Tertiary; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Structure-Activity Relationship; Temperature; Thermodynamics

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

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

As a large family of regulatory proteins, WRKY transcription factors play essential roles in the processes of adaptation to diverse environmental stresses and plant growth and development. Although several studies have investigated the role of WRKY transcription factors during these processes, the mechanisms underlying the function of WRKY members need to be further explored, and research focusing on the WRKY family in cotton crops is extremely limited.. In the present study, a gene encoding a putative WRKY family member, GhWRKY15, was isolated from cotton. GhWRKY15 is present as a single copy gene, and a transient expression analysis indicated that GhWRKY15 was localised to the nucleus. Additionally, a group of cis-acting elements associated with the response to environmental stress and plant growth and development were detected in the promoter. Consistently, northern blot analysis showed that GhWRKY15 expression was significantly induced in cotton seedlings following fungal infection or treatment with salicylic acid, methyl jasmonate or methyl viologen. Furthermore, GhWRKY15-overexpressing tobacco exhibited more resistance to viral and fungal infections compared with wild-type tobacco. The GhWRKY15-overexpressing tobacco also exhibited increased RNA expression of several pathogen-related genes, NONEXPRESSOR OF PR1, and two genes that encode enzymes involved in ET biosynthesis. Importantly, increased activity of the antioxidant enzymes POD and APX during infection and enhanced expression of NtAPX1 and NtGPX in transgenic tobacco following methyl viologen treatment were observed. Moreover, GhWRKY15 transcription was greater in the roots and stems compared with the expression in the cotyledon of cotton, and the stems of transgenic plants displayed faster elongation at the earlier shooting stages compared with wide type tobacco. Additionally, exposure to abiotic stresses, including cold, wounding and drought, resulted in the accumulation of GhWRKY15 transcripts.. Overall, our data suggest that overexpression of GhWRKY15 may contribute to the alteration of defence resistance to both viral and fungal infections, probably through regulating the ROS system via multiple signalling pathways in tobacco. It is intriguing that GhWRKY15 overexpression in tobacco affects plant growth and development, especially stem elongation. This finding suggests that the role of the WRKY proteins in disease resistance may be closely related to their function in regulating plant growth and development.

Topics: Acetates; Amino Acid Sequence; Blotting, Northern; Cell Nucleus; Cloning, Molecular; Cyclopentanes; Disease Resistance; Droughts; Fusarium; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Genes, Plant; Gossypium; Molecular Sequence Data; Nicotiana; Oxidation-Reduction; Oxylipins; Paraquat; Plant Diseases; Plant Immunity; Plant Roots; Plants, Genetically Modified; Promoter Regions, Genetic; Reactive Oxygen Species; Regulatory Sequences, Nucleic Acid; Salicylic Acid; Stress, Physiological; Tobacco Mosaic Virus; Transcription Factors

NPR1 is a gene of Arabidopsis thaliana required for the perception of salicylic acid. This perception triggers a defense response and negatively regulates the perception of jasmonates. Surprisingly, the application of methyl jasmonate also induces resistance, and NPR1 is also suspected to be relevant. Since an allelic series of npr1 was recently described, the behavior of these alleles was tested in response to methyl jasmonate.. The response to methyl jasmonate of different npr1s alleles and NPR1 paralogs null mutants was measured by the growth of a pathogen. We have also tested the subcellular localization of some npr1s, along with the protein-protein interactions that can be measured in yeast. The localization of the protein in npr1 alleles does not affect the response to methyl jasmonate. In fact, NPR1 is not required. The genes that are required in a redundant fashion are the BOPs. The BOPs are paralogs of NPR1, and they physically interact with the TGA family of transcription factors.. Some npr1 alleles have a phenotype in this response likely because they are affecting the interaction between BOPs and TGAs, and these two families of proteins are responsible for the resistance induced by methyl jasmonate in wild type plants.

Topics: Acetates; Alleles; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Disease Resistance; Gene Expression Regulation, Plant; Oxylipins; Phenotype; Plants, Genetically Modified

We treated Norway spruce (Picea abies) stems with methyl jasmonate (MeJA) to determine possible quantitative and qualitative effects of induced tree defenses on pheromone emission by the spruce bark beetle Ips typographus. We measured the amounts of 2-methyl-3-buten-2-ol and (S)-cis-verbenol, the two main components of the beetle's aggregation pheromone, released from beetle entrance holes, along with phloem terpene content and beetle performance in MeJA-treated and untreated Norway spruce logs. As expected, phloem terpene levels were higher and beetle tunnel length was shorter (an indication of poor performance) in MeJA-treated logs relative to untreated logs. Parallel to the higher phloem terpene content and poorer beetle performance, beetles in MeJA-treated logs released significantly less 2-methyl-3-buten-2-ol and (S)-cis-verbenol, and the ratio between the two pheromone components was significantly altered. These results suggest that host resistance elicited by MeJA application reduces pheromone emission by I. typographus and alters the critical ratio between the two main pheromone components needed to elicit aggregation. The results also provide a mechanistic explanation for the reduced performance and attractivity observed in earlier studies when bark beetles colonize trees with elicited host defenses, and extend our understanding of the ecological functions of conifer resistance against bark beetles.

Topics: Acetates; Animals; Coleoptera; Cyclopentanes; Disease Resistance; Ecosystem; Norway; Oxylipins; Pheromones; Plant Bark; Plant Diseases; Plant Growth Regulators; Terpenes