2-(2--pyridyldithio)benzyldiazoacetate and jasmonic-acid

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

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

Peroxisome-localized oxo-phytodienoic acid (OPDA) reductases (OPR) are enzymes converting 12-OPDA into jasmonic acid (JA). However, the biochemical and physiological functions of the cytoplasmic non-JA producing OPRs remain largely unknown. Here, we generated Mutator-insertional mutants of the maize OPR2 gene and tested its role in resistance to pathogens with distinct lifestyles. Functional analyses showed that the opr2 mutants were more susceptible to the (hemi)biotrophic pathogens Colletotrichum graminicola and Ustilago maydis, but were more resistant to the necrotrophic fungus Cochliobolus heterostrophus. Hormone profiling revealed that increased susceptibility to C. graminicola was associated with decreased salicylic acid (SA) but increased JA levels. Mutation of the JA-producing lipoxygenase 10 (LOX10) reversed this phenotype in the opr2 mutant background, corroborating the notion that JA promotes susceptibility to this pathogen. Exogenous SA did not rescue normal resistance levels in opr2 mutants, suggesting that this SA-inducible gene is the key downstream component of the SA-mediated defences against C. graminicola. Disease assays of the single and double opr2 and lox10 mutants and the JA-deficient opr7opr8 mutants showed that OPR2 negatively regulates JA biosynthesis, and that JA is required for resistance against C. heterostrophus. Overall, this study uncovers a novel function of a non-JA producing OPR as a major negative regulator of JA biosynthesis during pathogen infection, a function that leads to its contrasting contribution to either resistance or susceptibility depending on pathogen lifestyle.

Topics: Cyclopentanes; Gene Expression Regulation, Plant; Oxidoreductases; Oxylipins; Salicylic Acid

Different plant species employ different jasmonates to activate a conserved signalling pathway in land plants, where (+)-7-iso-JA-Ile (JA-Ile) is the ligand for the COI1/JAZ receptor in angiosperms and dn-cis-OPDA, dn-iso-OPDA and Δ

Topics: Biosynthetic Pathways; Cyclopentanes; Isoleucine; Ligands; Oxylipins; Phylogeny; Plants

In plant, APETALA2/ethylene-responsive factor (AP2/ERF)-domain transcription factors are important in regulating abiotic stress tolerance. In this study, ZmEREB57 encoding a AP2/ERF transcription factor was identified and its function was investigated in maize. ZmEREB57 is a nuclear protein with transactivation activity induced by several abiotic stress types. Furthermore, two CRISPR/Cas9 knockout lines of ZmEREB57 showed enhanced sensitivity to saline conditions, whereas the overexpression of ZmEREB57 increased salt tolerance in maize and Arabidopsis. DNA affinity purification sequencing (DAP-Seq) analysis revealed that ZmEREB57 notably regulates target genes by binding to promoters containing an O-box-like motif (CCGGCC). ZmEREB57 directly binds to the promoter of ZmAOC2 involved in the synthesis of 12-oxo-phytodienoic acid (OPDA) and jasmonic acid (JA). Transcriptome analysis revealed that several genes involved in regulating stress and redox homeostasis showed differential expression patterns in OPDA- and JA-treated maize seedlings exposed to salt stress compared to those treated with salt stress alone. Analysis of mutants deficient in the biosynthesis of OPDA and JA revealed that OPDA functions as a signalling molecule in the salt response. Our results indicate that ZmEREB57 involves in salt tolerance by regulating OPDA and JA signalling and confirm early observations that OPDA signalling functions independently of JA signalling.

Topics: Arabidopsis; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins; Salt Tolerance; Transcription Factors; Zea mays

13-Lipoxygenases (LOXs) initiate the synthesis of jasmonic acid (JA), the best-understood oxylipin hormone in herbivory defense. However, the roles of 9-LOX-derived oxylipins in insect resistance remain unclear. Here, we report a novel anti-herbivory mechanism mediated by a tonoplast-localized 9-LOX, ZmLOX5, and its linolenic acid-derived product, 9-hydroxy-10-oxo-12(Z),15(Z)-octadecadienoic acid (9,10-KODA). Transposon-insertional disruption of ZmLOX5 resulted in the loss of resistance to insect herbivory. lox5 knockout mutants displayed greatly reduced wound-induced accumulation of multiple oxylipins and defense metabolites, including benzoxazinoids, abscisic acid (ABA), and JA-isoleucine (JA-Ile). However, exogenous JA-Ile failed to rescue insect defense in lox5 mutants, while applications of 1 μM 9,10-KODA or the JA precursor, 12-oxo-phytodienoic acid (12-OPDA), restored wild-type resistance levels. Metabolite profiling revealed that exogenous 9,10-KODA primed the plants for increased production of ABA and 12-OPDA, but not JA-Ile. While none of the 9-oxylipins were able to rescue JA-Ile induction, the lox5 mutant accumulated lower wound-induced levels of Ca

Topics: Abscisic Acid; Animals; Cyclopentanes; Hormones; Insecta; Lipoxygenases; Oxylipins; Zea mays

The links between wound-response electrical signalling and the activation of jasmonate synthesis are unknown. We investigated damage-response remodelling of jasmonate precursor pools in the Arabidopsis thaliana leaf vasculature. Galactolipids and jasmonate precursors in primary veins from undamaged and wounded plants were analysed using MS-based metabolomics and NMR. In parallel, DAD1-LIKE LIPASEs (DALLs), which control the levels of jasmonate precursors in veins, were identified. A novel galactolipid containing the jasmonate precursor 12-oxo-phytodienoic acid (OPDA) was identified in veins: sn-2-O-(cis-12-oxo-phytodienoyl)-sn-3-O-(β-galactopyranosyl) glyceride (sn-2-OPDA-MGMG). Lower levels of sn-1-OPDA-MGMG were also detected. Vascular OPDA-MGMGs, sn-2-18:3-MGMG and free OPDA pools were reduced rapidly in response to damage-activated electrical signals. Reduced function dall2 mutants failed to build resting vascular sn-2-OPDA-MGMG and OPDA pools and, upon wounding, dall2 produced less jasmonoyl-isoleucine (JA-Ile) than the wild-type. DALL3 acted to suppress excess JA-Ile production after wounding, whereas dall2 dall3 double mutants strongly reduce jasmonate signalling in leaves distal to wounds. LOX6 and DALL2 function to produce OPDA and the non-bilayer-forming lipid sn-2-OPDA-MGMG in the primary vasculature. Membrane depolarizations trigger rapid depletion of these molecules. We suggest that electrical signal-dependent lipid phase changes help to initiate vascular jasmonate synthesis in wounded leaves.

Topics: Arabidopsis; Cyclopentanes; Oxylipins

Cis-(+)-12-oxophytodienoic acid (cis-(+)-OPDA) is a bioactive jasmonate, a precursor of jasmonic acid, which also displays signaling activity on its own. Modulation of cis-(+)-OPDA actions may be carried out via biotransformation leading to metabolites of various functions. This work introduces a methodology for the synthesis of racemic cis-OPDA conjugates with amino acids (OPDA-aa) and their deuterium-labeled analogs, which enables the unambiguous identification and accurate quantification of these compounds in plants. We have developed a highly sensitive liquid chromatography-tandem mass spectrometry-based method for the reliable determination of seven OPDA-aa (OPDA-Alanine, OPDA-Aspartate, OPDA-Glutamate, OPDA-Glycine, OPDA-Isoleucine, OPDA-Phenylalanine, and OPDA-Valine) from minute amount of plant material. The extraction from 10 mg of fresh plant tissue by 10% aqueous methanol followed by single-step sample clean-up on hydrophilic-lipophilic balanced columns prior to final analysis was optimized. The method was validated in terms of accuracy and precision, and the method parameters such as process efficiency, recovery and matrix effects were evaluated. In mechanically wounded 30-day-old Arabidopsis thaliana leaves, five endogenous (+)-OPDA-aa were identified and their endogenous levels were estimated. The time-course accumulation revealed a peak 60 min after the wounding, roughly corresponding to the accumulation of cis-(+)-OPDA. Our synthetic and analytical methodologies will support studies on cis-(+)-OPDA conjugation with amino acids and research into the biological significance of these metabolites in plants.

Topics: Amino Acids; Cyclopentanes; Diazonium Compounds; Oxylipins

12-oxo-phytodienoic acid (OPDA) is a biosynthetic precursor of jasmonic acid and triggers multiple biological processes from plant development to stress responses. However, the OPDA signaling and relevant regulatory networks were largely unknown in basal land plants. Using an integrated multi-omics technique, we investigated the global features in metabolites and transcriptional profiles of an Antarctic moss (

Topics: Bryophyta; Bryopsida; Cyclopentanes; Gene Expression Regulation, Plant; Oxylipins

Jasmonates are phytohormones that regulate defense and developmental processes in land plants. Despite the chemical diversity of jasmonate ligands in different plant lineages, they are all perceived by COI1/JAZ co-receptor complexes, in which the hormone acts as a molecular glue between the COI1 F-box and a JAZ repressor. It has been shown that COI1 determines ligand specificity based on the receptor crystal structure and the identification of a single COI1 residue, which is responsible for the evolutionary switch in ligand binding. In this work, we show that JAZ proteins contribute to ligand specificity together with COI1. We propose that specific features of JAZ proteins, which are conserved in bryophytes and lycophytes, enable perception of dn-OPDA ligands regardless the size of the COI1 binding pocket. In vascular plant lineages beyond lycophytes, JAZ evolved to limit binding to JA-Ile, thus impeding dn-OPDA recognition by COI1.

Topics: Ligands; Oxylipins; Plant Growth Regulators

Topics: Basic Helix-Loop-Helix Transcription Factors; Cyclopentanes; Diazonium Compounds; Marchantia; Oxylipins; Pyridines

Light-dependent seed germination is induced by gibberellins (GA) and inhibited by abscisic acid (ABA). The widely accepted view of the GA/ABA ratio controlling germination does not, however, explain the fact that seeds deficient in ABA still germinate poorly under shade conditions that repress germination. In Arabidopsis, MOTHER-OF-FT-AND-TFL1 (MFT) acts as a key negative regulator of germination, modulating GA and ABA responses under shade conditions. Under full light the oxylipin cis-12-oxo-phytodienoic acid (OPDA), a precursor of the stress-related phytohormone jasmonic acid, interacts with ABA and MFT to repress germination. Here, we show that under shade conditions both OPDA and ABA repress germination to varying extents. We demonstrate that the level of shade-induced MFT expression influences the ability of OPDA and/or ABA to fully repress germination. We also found that MFT expression decreases with seed age and this again correlates with the response of seeds to OPDA and ABA. We conclude that OPDA plays an essential role alongside ABA in repressing germination in response to shade and the combined effect of these phytohormones is integrated to a significant extent through MFT.

Topics: Abscisic Acid; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Diazonium Compounds; Gene Expression Regulation, Plant; Germination; Gibberellins; Light; Oxylipins; Plant Growth Regulators; Pyridines; Seeds

Jasmonates (JAs) are plant hormones that integrate external stress stimuli with physiological responses. (+)-7-iso-JA-L-Ile is the natural JA ligand of COI1, a component of a known JA receptor. The upstream JA biosynthetic precursor cis-(+)-12-oxo-phytodienoic acid (cis-(+)-OPDA) has been reported to act independently of COI1 as an essential signal in several stress-induced and developmental processes. Wound-induced increases in the endogenous levels of JA/JA-Ile are accompanied by two to tenfold increases in the concentration of OPDA, but its means of perception and metabolism are unknown. To screen for putative OPDA metabolites, vegetative tissues of flowering Arabidopsis thaliana were extracted with 25% aqueous methanol (v/v), purified by single-step reversed-phase polymer-based solid-phase extraction, and analyzed by high throughput mass spectrometry. This enabled the detection and quantitation of a low abundant OPDA analog of the biologically active (+)-7-iso-JA-L-Ile in plant tissue samples. Levels of the newly identified compound and the related phytohormones JA, JA-Ile and cis-(+)-OPDA were monitored in wounded leaves of flowering Arabidopsis lines (Col-0 and Ws) and compared to the levels observed in Arabidopsis mutants deficient in the biosynthesis of JA (dde2-2, opr3) and JA-Ile (jar1). The observed cis-(+)-OPDA-Ile levels varied widely, raising questions concerning its role in Arabidopsis stress responses.

Topics: Arabidopsis; Cyclopentanes; Diazonium Compounds; Fatty Acids, Unsaturated; Flowers; Isoleucine; Oxylipins; Plant Growth Regulators; Plant Leaves; Pyridines; Stereoisomerism

The endophytic fungus Piriformospora indica colonizes Arabidopsis thaliana roots and promotes plant performance, growth and resistance/tolerance against abiotic and biotic stress. Here we demonstrate that the benefits for the plant increase when the two partners are co-cultivated under stress (limited access to nutrient, exposure to heavy metals and salt, light and osmotic stress, pathogen infection). Moreover, physical contact between P. indica and Arabidopsis roots is necessary for optimal growth promotion, and chemical communication cannot replace the physical contact. Lower nutrient availability down-regulates and higher nutrient availability up-regulates the plant defense system including the expression of pathogenesis-related genes in roots. High light, osmotic and salt stresses support the beneficial interaction between the plant and the fungus. P. indica reduces stomata closure and H2O2 production after Alternaria brassicae infection in leaves and suppresses the defense-related accumulation of the phytohormone jasmonic acid. Thus, shifting the growth conditions toward a stress promotes the mutualistic interaction, while optimal supply with nutrients or low stress diminishes the benefits for the plant in the symbiosis.

Topics: Arabidopsis; Basidiomycota; Cyclopentanes; Diazonium Compounds; Host-Pathogen Interactions; Isoleucine; Light; Metals, Heavy; Nitrates; Osmotic Pressure; Oxylipins; Phosphates; Plant Roots; Plant Shoots; Pyridines; Seedlings; Stress, Physiological; Sulfates

Arginase induction can play a defensive role through the reduction of arginine availability for phytophageous insects. Arginase activity is also induced during gall growth caused by Plasmodiophora brassicae infection in roots of Arabidopsis thaliana; however, its possible role in this context has been unclear. We report here that the mutation of the arginase-encoding gene ARGAH2 abrogates clubroot-induced arginase activity and results in enhanced gall size in infected roots, suggesting that arginase plays a defensive role. Induction of arginase activity in infected roots was impaired in the jar1 mutant, highlighting a link between the arginase response to clubroot and jasmonate signaling. Clubroot-induced accumulation of the principal amino acids in galls was not affected by the argah2 mutation. Because ARGAH2 was previously reported to control auxin response, we investigated the role of ARGAH2 in callus induction. ARGAH2 was found to be highly induced in auxin/cytokinin-triggered aseptic plant calli, and callus development was enhanced in argah2 in the absence of the pathogen. We hypothesized that arginase contributes to a negative control over clubroot symptoms, by reducing hormone-triggered cellular proliferation.

Topics: Amidohydrolases; Amino Acids; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Diazonium Compounds; Enzyme Induction; Hydroxylation; Isoleucine; Mutation; Organ Specificity; Oxylipins; Plant Epidermis; Plant Roots; Plant Tumors; Plasmodiophorida; Pyridines

Nitric oxide-associated protein 1 (NOA1) is involved in various abiotic stress responses and is required for plant resistance to pathogen infections. However, the role of NOA1 in plant-herbivore interactions has not been explored. We created NOA1-silenced Nicotiana attenuata plants (irNaNOA1). Compared with wild-type (WT) plants, irNaNOA1 plants had highly decreased photosynthesis rates. We further examined various traits important for plant defense against its specialist herbivore Manduca sexta by treating WT and irNaNOA1 plants with mechanical wounding and M. sexta oral secretions (OS). NOA1-silenced plants showed elevated levels of herbivory-induced jasmonic acid (JA), but decreased JA-isoleucine conjugate (JA-Ile) levels. The decreased JA-Ile levels did not result from compromised JAR (jasmonic acid resistant) activity in irNOA1 plants. Moreover, nitrogen-rich defensive compounds, nicotine and trypsin proteinase inhibitors, did not differ between WT and irNaNOA1 plants. In contrast, concentrations of most carbon-based defensive compounds were lower in these plants than in WT plants, although the levels of chlorogenic acid were not changed. Therefore, silencing NOA1 alters the allocation of carbon resources within the phenylpropanoid pathway. These data suggest the involvement of NOA1 in N. attenuata's defense against M. sexta attack, and highlight its role in photosynthesis, and biosynthesis of jasmonates and secondary metabolites.

Topics: Animals; Carbon; Chlorophyll; Cloning, Molecular; Cyclopentanes; Diazonium Compounds; Feeding Behavior; Gene Expression Regulation, Plant; Gene Silencing; Isoleucine; Larva; Manduca; Nicotiana; Oxylipins; Photosynthesis; Plant Proteins; Pyridines; RNA, Messenger

Plant defensive strategies bring into play blends of compounds dependent on the type of attacker and coming from different synthesis pathways. Interest in the field is mainly focused on volatile organic compounds (VOCs) and jasmonic acid (JA). By contrast, little is known about the oxidized polyunsaturated fatty acids (PUFAs), such as PUFA-hydroperoxides, PUFA-hydroxides, or PUFA-ketones. PUFA-hydroperoxides and their derivatives might be involved in stress response and show antimicrobial activities. Hydroperoxides are also precursors of JA and some volatile compounds. In this paper, the differential biochemical response of a plant against insects with distinct feeding behaviours is characterized not only in terms of VOC signature and JA profile but also in terms of their precursors synthesized through the lipoxygenase (LOX)-pathway at the early stage of the plant response. For this purpose, two leading pests of potato with distinct feeding behaviours were used: the Colorado Potato Beetle (Leptinotarsa decemlineata Say), a chewing herbivore, and the Green Peach Aphid (Myzus persicae Sulzer), a piercing-sucking insect. The volatile signatures identified clearly differ in function with the feeding behaviour of the attacker and the aphid, which causes the smaller damages, triggers the emission of a higher number of volatiles. In addition, 9-LOX products, which are usually associated with defence against pathogens, were exclusively activated by aphid attack. Furthermore, a correlation between volatiles and JA accumulation and the evolution of their precursors was determined. Finally, the role of the insect itself on the plant response after insect infestation was highlighted.

Topics: Animals; Aphids; Coleoptera; Cyclopentanes; Diazonium Compounds; Feeding Behavior; Kinetics; Linoleic Acids; Lipid Peroxides; Lipoxygenase; Oxylipins; Pyridines; Solanum tuberosum; Volatile Organic Compounds

Octadecanoid pathway components, 12-oxo-phytodieonic acid (OPDA) and jasmonic acid (JA), are key biologically active regulators of plant self-defense response(s). However, to date these compounds have been studied mostly in dicots, and used large (1-10 g fresh weight, FW) samples for quantification, even when examined in mature rice plants, which is a drawback considering their rapid responsiveness to stress. Focusing on rice--a monocot cereal crop research model--this work describes an efficient and simultaneous quantification of both OPDA and JA using a minimum amount of 200mg FW seedling leaf tissue upon wounding (by cut) and treatment with fungal elicitor, chitosan (CT) by high-pressure liquid chromatography-turboionspray tandem mass spectrometry. Transient OPDA/JA "burst" was consistently and reproducibly detected within 3 min in wounded and CT treated leaves. OPDA peaked dramatically around 5 min and returned to its basal level within 15 min, whereas JA induction upon wounding and CT treatment were in parallel to OPDA production, peaking at 30 and 60 min, respectively. Present results mark a major advance in our understanding of key inducible octadecanoid pathway components in rice, and strongly suggest a role for the octadecanoid pathway downstream of perception of at least these two fundamentally different extracellular stimuli.

Topics: Antigens, Fungal; Chitin; Chitosan; Cyclopentanes; Diazonium Compounds; Oryza; Oxylipins; Plant Leaves; Pyridines; Signal Transduction; Wound Healing; Wounds and Injuries