jasmonic-acid and azelaic-acid

Efficient communication between the pest-colonised and non-colonised organs is vital for the timely manifestation of defences that restrict systemic spread of pests. The vasculature provides an important conduit for translocation of signals that contribute to long-distance communication within a plant. Airborne signals also contribute to this process. In recent years, major advances have been made in identifying metabolites that are candidate systemic signals in plant defence against pathogens. Methyl salicylate, jasmonates, azelaic acid and a diterpenoid have been implicated as mobile signals associated with the activation of systemic acquired resistance (SAR), which confers enhanced resistance against a broad spectrum of pathogens. By contrast, auxins probably contribute to negative regulation of systemic defences.

Topics: Cyclopentanes; Dicarboxylic Acids; Diterpenes; Host-Pathogen Interactions; Immunity, Innate; Oxylipins; Plants; Pseudomonas syringae; Salicylates; Signal Transduction; Xanthomonas

Barley (Hordeum vulgare) is the fourth crop cultivated in the world for human consumption and animal feed, making it important to breed healthy and productive plants. Among the threats for barley are lodging, diseases, and pathogens. To avoid lodging, dwarf and semi-dwarf mutants have been selected through breeding processes. Most of these mutants are affected on hormonal biosynthesis or signalling. Here, we present the metabolic characterization of a brassinosteroid insensitive semi-dwarf mutant, BW312. The hormone profile was determined through a targeted metabolomics analysis by UHPLC-triple quadrupole-MS/MS, showing an induction of gibberellic acid and jasmonic acid in the semi-dwarf mutant. A non-targeted metabolomics analysis by UHPLC-QTOF-MS/MS revealed a differential metabolic profile, with 16 and 9 metabolites showing higher intensities in the mutant and wild-type plants respectively. Among these metabolites, azelaic acid was identified. Gibberellic acid, jasmonic acid, and azelaic acid are involved in pathogen resistance, showing that this semi-dwarf line has an enhanced basal pathogen resistance in absence of pathogens, and therefore is of interest in breeding programs to fight against lodging, but also probably to increase pathogen resistance.

Topics: Brassinosteroids; Chromatography, High Pressure Liquid; Cyclopentanes; Dicarboxylic Acids; Gibberellins; Hordeum; Metabolome; Metabolomics; Mutation; Oxylipins; Phenotype; Plant Breeding; Plant Proteins; Tandem Mass Spectrometry

Feeding by insect herbivores activates plant signaling pathways, resulting in the enhanced production of secondary metabolites and other resistance-related traits by injured plants. These traits can reduce insect fitness, deter feeding, and attract beneficial insects. Organic and inorganic chemicals applied as a foliar spray, seed treatment, or soil drench can activate these plant responses. Azelaic acid (AA), benzothiadiazole (BTH), gibberellic acid (GA), harpin, and jasmonic acid (JA) are thought to directly mediate plant responses to pathogens and herbivores or to mimic compounds that do. The effects of these potential elicitors on the induction of plant defenses were determined by measuring the weight gains of fall armyworm, Spodoptera frugiperda (J. E. Smith) (FAW) (Lepidoptera: Noctuidae) larvae on four crop plants, cotton, corn, rice, and soybean, treated with the compounds under greenhouse conditions. Treatment with JA consistently reduced growth of FAW reared on treated cotton and soybean. In contrast, FAW fed BTH- and harpin-treated cotton and soybean tissue gained more weight than those fed control leaf tissue, consistent with negative crosstalk between the salicylic acid and JA signaling pathways. No induction or inconsistent induction of resistance was observed in corn and rice. Follow-up experiments showed that the co-application of adjuvants with JA failed to increase the effectiveness of induction by JA and that soybean looper [Chrysodeixis includens (Walker)], a relative specialist on legumes, was less affected by JA-induced responses in soybean than was the polyphagous FAW. Overall, the results of these experiments demonstrate that the effectiveness of elicitors as a management tactic will depend strongly on the identities of the crop, the pest, and the elicitor involved.

Topics: Animals; Crops, Agricultural; Cyclopentanes; Dicarboxylic Acids; Disease Resistance; Gibberellins; Glycine max; Gossypium; Herbivory; Oryza; Oxylipins; Spodoptera; Thiadiazoles; Zea mays

Plants induce long-lasting systemic immunity after local pathogen attack by emitting resistance-priming signals from infection sites. A number of plant molecules have been proposed as mobile factors for this response, but many do not fully satisfy criteria for timing and action in systemic immunity. Azelaic acid has been identified as a pathogen-induced metabolite in Arabidopsis vascular sap that has several properties of a long-distance resistance-priming signal.

Topics: Arabidopsis; Arabidopsis Proteins; Bacteria; Carrier Proteins; Cyclopentanes; Dicarboxylic Acids; Fatty Acid-Binding Proteins; Host-Pathogen Interactions; Immunity, Innate; Models, Biological; Oxylipins; Plant Diseases; Plant Leaves; Salicylic Acid; Signal Transduction