methyl-jasmonate and methyl-salicylate

The role played by phytohormone signaling in the modulation of DNA repair gene and the resulting effects on plant adaptation to genotoxic stress are poorly investigated. Information has been gathered using the Arabidopsis ABA (abscisic acid) overly sensitive mutant abo4-1, defective in the DNA polymerase ε function that is required for DNA repair and recombination. Similarly, phytohormone-mediated regulation of the Ku genes, encoding the Ku heterodimer protein involved in DNA repair, cell cycle control and telomere homeostasis has been demonstrated, highlighting a scenario in which hormones might affect genome stability by modulating the frequency of homologous recombination, favoring plant adaptation to genotoxic stress. Within this context, the characterisation of Arabidopsis AtKu mutants allowed disclosing novel connections between DNA repair and phytohormone networks. Another intriguing aspect deals with the emerging correlation between plant defense response and the mechanisms responsible for genome stability. There is increasing evidence that systemic acquired resistance (SAR) and homologous recombination share common elements represented by proteins involved in DNA repair and chromatin remodeling. This hypothesis is supported by the finding that volatile compounds, such as methyl salicylate (MeSA) and methyl jasmonate (MeJA), participating in the plant-to-plant communication can trigger genome instability in response to genotoxic stress agents. Phytohormone-mediated control of genome stability involves also chromatin remodeling, thus expanding the range of molecular targets. The present review describes the most significant advances in this specific research field, in the attempt to provide a better comprehension of how plant hormones modulate DNA repair proteins as a function of stress.

Topics: Abscisic Acid; Acetates; Cyclopentanes; DNA Repair; Gibberellins; Models, Biological; Oxylipins; Plant Growth Regulators; Salicylates; Salicylic Acid; Signal Transduction

The effects of postharvest treatments with γ-aminobutyric acid (GABA), methyl jasmonate (MeJA) or methyl salicylate (MeSA) on antioxidant systems and sensory quality of blood oranges during cold storage were evaluated (150 days at 3 °C plus 2 days at 20 °C, shelf life). Fruit firmness, titratable acidity (TA), total antioxidant activity (TAA) and ascorbic acid (AA) decreased during cold storage, all these changes being delayed in treated fruit, with the greatest differences observed with the 50 µmol L

Topics: Acetates; Anthocyanins; Catechol Oxidase; Citrus sinensis; Cold Temperature; Cyclopentanes; Food Preservation; Fruit; gamma-Aminobutyric Acid; Glucosides; Nutritive Value; Oxylipins; Phenylalanine Ammonia-Lyase; Salicylates

After herbivore attack, plants express inducible resistance-related traits activated by hormones, mainly jasmonic acid (JA) and salicylic acid (SA). Methyl jasmonate (MeJa) is a biologically active methyl ester of JA. Exogenous applications of JA, SA, and MeJa induce responses similar to herbivory by insects. In this study, rice, Oryza sativa L. (Poaceae), plants were treated with two concentrations of MeJa (2 and 5 mmol L. Nymphs developing on plants treated with SA 16 mmol L. Rice plants possess defense mechanisms that can be elicited using hormones as elicitors, mainly SA 16 mmol L

Topics: Acetates; Animals; Cyclopentanes; Herbivory; Heteroptera; Nymph; Oryza; Oxylipins; Plant Growth Regulators; Salicylates; Salicylic Acid; Volatile Organic Compounds

Blood orange is sensitive to chilling injury (CI) depending on cultivar and storage temperature. Postharvest treatments with γ-aminobutyric acid (GABA), methyl jasmonate (MeJA), or methyl salicylate (MeSA) are known to alleviate CI. γ-Aminobutyric acid aqueous solution, applied at 20 and 40 mM, was vacuum-infiltrated at 30 kPa for 8 min at 20 °C. Methyl jasmonate or MeSA vapor treatments were applied separately at 50 and 100 μM by putting the fruit in 20 L plastic containers for 18 h at 20 °C. There have been no reports about postharvest treatments of GABA, MeJA, or MeSA on enhancing the tolerance of 'Moro' blood orange to chilling during long-term cold storage at 3 °C for 150 days, which was the subject of this study.. All treatments significantly alleviated CI symptoms of blood orange manifested by lower electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H

Topics: Acetates; Ascorbate Peroxidases; Catalase; Citrus sinensis; Cold Temperature; Cyclopentanes; Food Preservation; Food Preservatives; Food Storage; Fruit; gamma-Aminobutyric Acid; Oxylipins; Plant Proteins; Salicylates

Low temperatures are often used to reduce metabolic processes and extend the storage life of fruit; however, in the case of avocado, a temperature below 3 °C will often result in the development of physiological disorders associated with chilling injury. The objective of this study was to investigate the ability of methyl jasmonate (MeJA) and methyl salicylate (MeSA) vapours to alleviate chilling injury in 'Hass' avocado fruit kept at 2 °C for 21 days followed by 6-7 days of shelf-life at 20 °C, simulating supply chain conditions.. The incidence and severity of chilling injury were significantly reduced in MeJA- and MeSA-exposed fruit, especially at 100 µmol L. MeJA and MeSA have the potential for being used with 'Hass' avocado fruit shipped at low temperature to reduce its susceptibility to chilling injury. © 2017 Society of Chemical Industry.

Topics: Acetates; Cold Temperature; Cyclopentanes; Fatty Acids; Food Preservation; Food Preservatives; Food Storage; Fruit; Oxylipins; Persea; Salicylates

Development of anthracnose disease caused by Colletotrichum gloeosporioides Penz. is one of the major issues within the avocado supply chain. Exposure to methyl jasmonate (MeJA) and methyl salicylate (MeSA) vapours at 10 and 100µmoll

Topics: Acetates; Colletotrichum; Cyclopentanes; Fruit; Fungicides, Industrial; Oxylipins; Persea; Plant Diseases; Salicylates

The known members of plant methyl esterase (MES) family catalyze the hydrolysis of a C-O ester linkage of methyl esters of several phytohormones including indole-3-acetic acid, salicylic acid and jasmonic acid. The genome of grapevine (Vitis vinifera) was found to contain 15 MES genes, designated VvMES1-15. In this report, VvMES5 was selected for molecular, biochemical and structural studies. VvMES5 is most similar to tomato methyl jasmonate esterase. E. coli-expressed recombinant VvMES5 displayed methyl jasmonate (MeJA) esterase activity, it was renamed VvMJE1. Under steady-state conditions, VvMJE1 exhibited an apparent Km value of 92.9 μM with MeJA. VvMJE1 was also shown to have lower activity with methyl salicylate (MeSA), another known substrate of the MES family, and only at high concentrations of the substrate. To understand the structural basis of VvMJE1 in discriminating MeJA and MeSA, a homolog model of VvMJE1 was made using the X-ray structure of tobacco SABP2, which encodes for methyl salicylate esterase, as a template. Interestingly, two bulky residues at the binding site and near the surface of tobacco SABP2 are replaced by relatively small residues in VvMJE1. Such a change enables the accommodation of a larger substrate MeJA in VvMJE1. The expression of VvMJE1 was compared in control grape plants and grape plants treated with one of the three stresses: heat, cold and UV-B. While the expression of VvMJE1 was not affected by heat treatment, its expression was significantly up-regulated by cold treatment and UV-B treatment. This result suggests that VvMJE1 has a role in response of grape plants to these two abiotic stresses.

Topics: Acetates; Aldehyde-Lyases; Crystallography, X-Ray; Cyclopentanes; Nicotiana; Oxylipins; Plant Proteins; Salicylates; Stress, Physiological; Structural Homology, Protein; Vitis

Vegetation emits a class of oxygenated hydrocarbons--the green leaf volatiles (GLVs)--under stress or damage. Under foggy conditions GLVs might be a source of secondary organic aerosol (SOA) via aqueous reactions with hydroxyl radical (OH), singlet oxygen ((1)O2*), and excited triplet states ((3)C*). To examine this, we determined the aqueous kinetics and SOA mass yields for reactions of (3)C* and (1)O2* with five GLVs: methyl jasmonate (MeJa), methyl salicylate (MeSa), cis-3-hexenyl acetate (HxAc), cis-3-hexen-1-ol (HxO), and 2-methyl-3-butene-2-ol (MBO). Second-order rate constants with (3)C* and (1)O2* range from (0.13-22) × 10(8) M(-1) s(-1) and (8.2-60) × 10(5) M(-1) s(-1) at 298 K, respectively. Rate constants with (3)C* are independent of temperature, while values with (1)O2* show significant temperature dependence (Ea = 20-96 kJ mol(-1)). Aqueous SOA mass yields for oxidation by (3)C* are (84 ± 7)%, (80 ± 9)%, and (38 ± 18)%, for MeJa, MeSa, and HxAc, respectively; we did not measure yields for other conditions because of slow kinetics. The aqueous production of SOA from GLVs is dominated by (3)C* and OH reactions, which form low volatility products at a rate that is approximately half that from the parallel gas-phase reactions of GLVs.

Topics: Acetates; Aerosols; Cyclopentanes; Hexanols; Hydroxyl Radical; Kinetics; Oxygen; Oxylipins; Pentanols; Plant Leaves; Salicylates; Singlet Oxygen; Temperature; Volatile Organic Compounds; Volatilization; Water

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

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

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

Coniferous trees have both constitutive and inducible defences that deter or kill herbivores and pathogens. We investigated constitutive and induced monoterpene responses of jack pine (Pinus banksiana Lamb.) to a number of damage types: a fungal associate of the mountain pine beetle (Dendroctonus ponderosae Hopkins), Grosmannia clavigera (Robinson-Jeffrey & R.W. Davidson); two phytohormones, methyl jasmonate (MJ) and methyl salicylate (MS); simulated herbivory; and mechanical wounding. We only included the fungal, MJ and mechanical wounding treatments in the field experiments while all treatments were part of the greenhouse studies. We focused on both constitutive and induced responses between juvenile and mature jack pine trees and differences in defences between phloem and needles. We found that phytohormone applications and fungal inoculation resulted in the greatest increase in monoterpenes in both juvenile and mature trees. Additionally, damage types differentially affected the proportions of individual monoterpenes: MJ-treated mature trees had higher myrcene and β-pinene than fungal-inoculated mature trees, while needles of juveniles inoculated with the fungus contained higher limonene than MJ- or MS-treated juveniles. Although the constitutive monoterpenes were higher in the phloem of juveniles than mature jack pine trees, the phloem of mature trees had a much higher magnitude of induction. Further, induced monoterpene concentrations in juveniles were higher in phloem than in needles. There was no difference in monoterpene concentration between phytohormone applications and G. clavigera inoculation in mature trees, while in juvenile trees MJ was different from both G. clavigera and simulated herbivory in needle monoterpenes, but there was no difference between phytohormone applications and simulated herbivory in the phloem.

Topics: Acetates; Animals; Ascomycota; Coleoptera; Cyclopentanes; Monoterpenes; Oxylipins; Phloem; Pinus; Plant Diseases; Plant Growth Regulators; Plant Immunity; Plant Leaves; Salicylates; Trees

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

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

Ca(2+) plays a critical role as second messenger in the signal-response coupling of plant defence responses, and methyl-jasmonate and methyl-salicylate are important components of signal transduction cascades activating plant defences. When intact axenic non-induced seedling roots of sunflower were treated with different Ca(2+) concentrations up to 1 mM, there was no significant increase in O(2)(*-) generation or DMAB-MBTH peroxidase (extracellular, ECPOX) activities in the apoplast, probably because these roots had enough Ca(2+) in their exo- and endocellular reservoirs. Both activities were strongly inhibited by the RBOH-NADPH oxidase inhibitor DPI and by the Ca(2+) surrogate antagonist La(3+), but the voltage-dependent Ca(2+) channel blocker verapamil was only inhibitory at concentrations higher than those active on animal L-type Ca(2+) channels. Concentrations >5 mM EGTA (chelating Ca(2+) in the apoplast) and Li(+) (inhibiting PI cycle dependent endogenous Ca(2+) fluxes) also inhibited both activities. W7, inhibitor of binding of Ca-CaM to its target protein, enhanced both activities, but the inactive analogue W5 showed a similar effect. Our data suggest that Ca(2+) from exocellular and, to a lesser extent, from endocellular stores is involved in oxidative activities, and that RBOH-NADPH oxidase is the main system supporting them. Ca(2+) activation of the PM cytosolic side of RBOH-NADPH oxidase is probably the key to Ca(2+) involvement in these processes. Roots induced by MeJA or MeSA showed significant enhancement of both oxidative activities, as corresponding to the oxidative burst evoked by the two phytohormones in the root apoplast. But while ECPOX activity showed a response to the effectors similar to that described above for non-induced roots, O(2)(*-) generation activity in the apoplast of induced roots was insensitive to EGTA, verapamil and Li(+), the inhibitors of exogenous and endogenous Ca(2+) fluxes; only DPI and La(3+) were inhibitory. As exogenously added 0.1 mM Ca(2+) also increased O (2) (.-) generation, we propose that, in these roots, activation of RBOH-NADPH oxidase by Ca(2+) could be regulated by Ca(2+) sensors in the apoplast.

Topics: Acetates; Calcium Signaling; Cyclopentanes; Helianthus; Oxidation-Reduction; Oxylipins; Plant Roots; Reactive Oxygen Species; Salicylates

Methyl jasmonate (MeJA) and methyl salicylate (MeSA) are important signaling molecules that induce plant defense against insect herbivores and microbial pathogens. We tested the hypothesis that allelopathy is an inducible defense mechanism, and that the JA and SA signaling pathways may activate allelochemicals release. Exogenous application of MeJA and MeSA to rice (Oryza sativa L.) enhanced rice allelopathic potential and led to accumulation of phenolics, an increase in enzymatic activities, and gene transcription of phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H), two key enzymes in the phenylpropanoid pathway. Aqueous extracts of the leaves of rice IAC165, a putative allelopathic variety, treated with MeSA (5 mM) or MeJA (0.05 mM), showed increased inhibitory effects (25 and 21%, respectively) on root growth of barnyardgrass (Echinochloa crus-galli L.), and increased inhibitory effects (18 and 23%, respectively) on shoot growth. Aqueous extracts from leaves of Huajingxian 1 rice, a putative nonallelopathic variety treated with MeJA and MeSA, caused 63 and 24% inhibition of root growth in barnyardgrass seedlings. The root exudates of both IAC165 and Huajingxian 1 plants treated with MeJA and MeSA for 48 hr also showed significant increases in their inhibitory effects on root growth of barnyardgrass seedlings. At the four-leaf stage, levels of 3,4-hydroxybenzoic acid, vanillic acid, coumaric acid, and ferulic acid that accumulated in the leaves were 5.3-, 31.3-, 2.2-, and 1.7-fold higher in response to MeJA exposure, and 3.3-, 13.1-, 2.0-, and 2.2-fold higher in response to MeSA. Treatments of MeSA and MeJA enhanced the PAL activity in the rice leaves up to 52.3 and 80.1%, respectively, whereas C4H activity was increased by 40.2 and 67%. Gene transcription of PAL and C4H in rice leaves significantly increased after the plants were subjected to treatment with MeJA and MeSA. These results suggest that allelopathy may be an active defense mechanism, and that plant signaling compounds are potentially valuable in its regulation.

Topics: Acetates; Carboxylic Acids; Cyclopentanes; Echinochloa; Oryza; Oxylipins; Phenylalanine Ammonia-Lyase; Pheromones; Plant Extracts; Plant Leaves; Plant Roots; Plant Shoots; Plant Stems; Salicylates; Trans-Cinnamate 4-Monooxygenase

AtPep1, a 23-aa peptide encoded by Arabidopsis PROPEP1, a member of a small, six-member gene family, activates expression of the defense gene PDF1.2 (encoding defensin) and its own precursor gene, PROPEP1, through the jasmonate/ethylene signaling pathway, mediated by a cell-surface receptor, PEPR1. Overexpression of two family members, PROPEP1 and PROPEP2, enhances resistance of Arabidopsis plants against the pathogen Pythium irregulare, and PROPEP2 and PROPEP3 are expressed at highly elevated levels in Arabidopsis in response to pathogen infections and to several pathogen-associated molecules (general elicitors). Here, we report that PDF1.2, PR-1 (pathogenesis protein), and PROPEP genes were differentially expressed in the leaves of intact plants sprayed with methyl jasmonate and methyl salicylate and in excised leaves supplied through cut petioles with peptides derived from the C terminus of each of the encoded proteins. The expression of PDF1.2 and PR-1 elicited by the peptides was blocked in mutant plants deficient in the jasmonate/ethylene and salicylate pathways, and in wild-type plants by treatment with diphenylene iodonium chloride, an inhibitor of hydrogen peroxide production. PROPEP1, PROPEP 2, and PROPEP3 genes appear to have roles in a feedback loop that amplifies defense signaling pathways initiated by pathogens.

Topics: Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Defensins; Gene Expression Regulation, Plant; Genes, Plant; Immunity, Innate; Models, Biological; Oxylipins; Plant Growth Regulators; Salicylates; Signal Transduction

Methyl salicylate (MeSA) vapor increased resistance against chilling injury (CI) in freshly harvested pink tomatoes. The expression patterns of alternative oxidase (AOX) before and during the chilling period demonstrated that pre-treatment of tomato fruit with MeSA vapor increased the transcript levels of AOX. We used 4 EST tomato clones of AOX from the public database that belong to two distinctly related families, 1 and 2 defined in plants. Three clones were designated as LeAOX1a, 1b and 1c and the fourth clone as LeAOX2. Using RT-PCR, 1a and 1b genes were found to be expressed in leaf, root and fruit tissues, but 1c was expressed preferentially in roots. RNA transcript from LeAOX1a of AOX subfamily 1 was present in much greater abundance than 1b or 1c. The presence of longer AOX transcripts detected by RNA gel blot analysis in cold-stored tomato fruit was confirmed to be the un-spliced pre-mRNA transcripts of LeAOX1a and LeAOX1b genes. Intron splicing of LeAOX1c gene was also affected by cold storage when it was detected in roots. This alternative splicing event in AOX pre-mRNAs molecules occurred, preferentially at low temperature, regardless of mRNA abundance. Transcript levels of several key genes involved in RNA processing (splicing factors: 9G8-SR and SF2-SR, fibrillarin and DEAD box RNA helicase) were also affected by changes in storage temperature. The aberrant splicing event in AOX pre-mRNA and its possible association with the change in expression of genes involved in RNA processing in tomato fruit having chilling disorder was discussed.

Topics: Acetates; Alternative Splicing; Cyclopentanes; Freezing; Gene Expression Regulation, Plant; Mitochondrial Proteins; Oxidoreductases; Oxylipins; Plant Proteins; RNA, Messenger; Salicylates; Solanum lycopersicum

Two distinct full-length cDNAs from rough lemon that encoded miraculin-like proteins were isolated by random amplification of cDNA ends (RACEs), based on sequence information from subtractive PCR previously described, and designated as RlemMLP1 and RlemMLP2. The transcripts of both RlemMLP1 and RlemMLP2 were not detected in leaves, or stems but accumulated in fruits. Transcripts accumulated to higher levels in leaves after wounding, inoculation with conidia of Alternaria alternata, or treatment with methyl jasmonate vapors. Treatment with methyl salicylate antagonized the signaling pathway of wounding. Treatment with methyl salicylate at 2 h after wounding significantly reduced wounding-induced gene expression of both RlemMLP1 and RlemMLP2. Protein products of these genes were obtained by using a prokaryotic expression system, and had protease inhibitor activity. RlemMLP2, but not RlemMLP1, contained a thaumatin motif, and only RlemMLP2 showed anti-fungal activity against Alternaria citri. Cellular localization analysis with RlemMLP1 or RlemMLP2 fused to a green fluorescence protein gene following transient translation using a particle bombardment in onion cells indicated that both RlemMLP1 and RlemMLP2 were localized to the cytosol. These evidences revealed that rough lemon RlemMLPs are likely to have defensive function against pathogens at least when host cells are broken by their infections.

Topics: Acetates; Amino Acid Sequence; Base Sequence; Citrus; Cloning, Molecular; Cyclopentanes; DNA, Complementary; DNA, Plant; Gene Expression Regulation, Plant; Molecular Sequence Data; Oxylipins; Plant Growth Regulators; Plant Proteins; RNA, Messenger; RNA, Plant; Salicylates

A tobacco peroxidase gene tpoxN1 was reported to be expressed within 1 h after wounding in leaves [Hiraga et al. (2000a) Plant Cell Physiol. 41: 165]. We describe here further results on the wound-induced tpoxN1 expression. The quick tpoxN1 induction occurred preferentially in stems and petioles, but was negligible in leaf blades even 8 h after wounding. Induced GUS activity was also detected rapidly after wounding in the stem of transgenic tobacco plants carrying the tpoxN1 promoter::GUS fusion gene, localized mainly in the vascular systems where it was maintained this level for 14 d or more. Strong GUS activity was also found in the petiole and veinlet as well as the epidermal tissue in the stem. Treatment of known inducers for wound-responsive genes such as jasmonate, 1-aminocyclopropane-1-carboxylate, spermine, phytohormones and other stress treatments did not enhance wound-induced tpoxN1 gene expression in stems at all, but rather repressed it in some cases. Studies using metabolic inhibitors suggested that phosphorylation and dephosphorylation of proteins together with de novo protein synthesis are likely to be involved in the wound-induced tpoxN1 expression as well as some other wound-responsive genes. Thus, tpoxN1 is a unique wound-inducible and possible wound-healing gene which is rapidly expressed being maintained for a long time in veins via an unknown wound-signaling pathway(s).

Topics: Acetates; Amino Acids, Cyclic; Brassinosteroids; Cholestanols; Cyclopentanes; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Histocytochemistry; Naphthaleneacetic Acids; Nicotiana; Oxylipins; Peroxidase; Phosphorylation; Plant Epidermis; Plant Growth Regulators; Plant Stems; Plants, Genetically Modified; RNA, Plant; Salicylates; Signal Transduction; Spermine; Steroids, Heterocyclic; Stress, Mechanical

Treatment of tomato (Lycopersicon esculentum L. cv. Beefstake) fruit with low concentrations of (0.01 mM) methyl jasmonate (MeJA) or methyl salicylate (MeSA) substantially enhanced their resistance to chilling temperature and decreased the incidence of decay during low-temperature storage. While studying the expression of pathogenesis-related (PR) protein genes, different accumulation patterns of PR-protein mRNAs in tomato fruit were observed. MeJA substantially increased the accumulation of PR-2b transcripts encoding intracellular beta-1,3-glucanase and enhanced the mRNA levels of PR-2a and PR-3b encoding extracellular beta-1,3-glucanase and intracellular chitinase, respectively. MeSA substantially increased accumulation of PR-2b and PR-3a mRNAs and slightly increased PR-3b mRNA accumulation. Chilling temperature did not appreciably enhance the accumulation of PR-protein mRNAs in untreated fruit. However, the accumulation of PR-3b mRNAs in MeSA-treated fruit was enhanced following low-temperature storage. Transcript abundance of catalase genes also was investigated in different pretreated tomatoes. The accumulation of cat1 mRNA was increased substantially by MeJA, while it was reduced by MeSA treatment. These results suggest that the pre-treatment of tomato fruit with MeSA or MeJA induces the synthesis of some stress proteins, such as PR proteins, which leads to increased chilling tolerance and resistance to pathogens, thereby decreasing the incidence of decay.

Topics: Acetates; beta-Glucosidase; Catalase; Chitinases; Cyclopentanes; Dose-Response Relationship, Drug; Freezing; Gene Expression Regulation, Plant; Glucan 1,3-beta-Glucosidase; Immunity, Innate; Oxylipins; Plant Proteins; RNA, Messenger; Salicylates; Solanum lycopersicum

In response to herbivore damage, several plant species emit volatiles that attract natural predators of the attacking herbivores. Using spider mites (Tetranychus urticae) and predatory mites (Phytoseiulus persimilis), it has been shown that not only the attacked plant but also neighbouring plants are affected, becoming more attractive to predatory mites and less susceptible to spider mites. The mechanism involved in such interactions, however, remains elusive. Here we show that uninfested lima bean leaves activate five separate defence genes when exposed to volatiles from conspecific leaves infested with T. urticae, but not when exposed to volatiles from artificially wounded leaves. The expression pattern of these genes is similar to that produced by exposure to jasmonic acid. At least three terpenoids in the volatiles are responsible for this gene activation; they are released in response to herbivory but not artificial wounding. Expression of these genes requires calcium influx and protein phosphorylation/dephosphorylation.

Topics: Acetates; Animals; Cyclopentanes; Egtazic Acid; Fabaceae; Female; Gene Expression Regulation, Plant; Lipoxygenase; Mites; Oils, Volatile; Oxylipins; Plant Oils; Plant Proteins; Plants, Medicinal; Salicylates; Terpenes; Transcriptional Activation; Volatilization