Volatile Methyl Jasmonate Research Articles

Volatile methyl jasmonate from roots triggers host-beneficial soil microbiome biofilms

The rhizosphere is a niche surrounding plant roots, where soluble and volatile molecules mediate signaling between plants and the associated microbiota. The preferred lifestyle of soil microorganisms is in the form of biofilms. However, less is known about whether root volatile organic compounds (rVOCs) can influence soil biofilms beyond the 2–10 mm rhizosphere zone influenced by root exudates. We report that rVOCs shift the microbiome composition and growth dynamics of complex soil biofilms. This signaling is evolutionarily conserved from ferns to higher plants. Methyl jasmonate (MeJA) is a bioactive signal of rVOCs that rapidly triggers both biofilm and microbiome changes. In contrast to the planktonic community, the resulting biofilm community provides ecological benefits to the host from a distance via growth enhancement. Thus, a volatile host defense signal, MeJA, is co-opted for assembling host-beneficial biofilms in the soil microbiota and extending the sphere of host influence in the rhizosphere.

Air-assisted liquid-liquid microextraction and enantioselective gas chromatography-tandem mass spectrometry quantification of methyl jasmonate stereoisomers in tea (Camellia sinensis L.)

Different stereoisomers of phytohormones may have different roles in plants while the quantification for stereoisomers still remains a challenge. The chiral separation method for methyl jasmonate (MeJA) in tea (Camellia sinensis L.) was developed by air-assisted liquid-liquid microextraction (AALLME) with enantioselective gas chromatography-mass spectrometry (Es-GC-MS/MS). The Plackett-Burman factorial design was introduced to optimize the multiple parameters of AALLME. Sensitive Es-GC-MS/MS enabled the quantification of the MeJA stereoisomers, which were separated from each other with resolutions of 3.5, 2.7, and 2.5. The linearities were R2 > 0.9971, the limits of detection were 0.08–0.12 ng/mL, the limits of quantification (LOD) were 0.28–0.39 ng/mL, and the recovery range was 80.60–107.03%. The method was applied to analyze the MeJA stereoisomer profiles in tea plants after geometrid feeding and mechanical wounding. (+)-MeJA appeared to be the main bio-active monomer that responded to injury stress. (+)-MeJA similarly increased in tea shoots at only 30 s after geometrid attack or mechanical wounding. The proposed method is superior as air-assisted liquid-liquid microextraction could induce the loss of volatile MeJA in a much shorter time, compared to the conventional enrichment procedure. A novel assay protocol for relative quantification of MeJA stereoisomers in plants responding to different injuries was applied.

Biosynthesis of orchid-like volatile methyl jasmonate in tea (Camellia sinensis) leaves in response to multiple stresses during the shaking process of oolong tea

Methyl jasmonate (MeJA), a significant fatty acid derivative, contributes to the main floral aroma of oolong tea. However, in tea plants, the mechanism of MeJA biosynthesis and the enzymes that participate in its formation is still unclear. In this study, the full length of the first jasmonic acid carboxyl methyltransferase (JMT) gene from Camellia sinensis was amplified and the biochemical function of the recombinant C. sinensis JMT (CsJMT) protein was studied after coexpression in Escherichia coli. The recombinant CsJMT protein could transfer the methyl groups to jasmonic acid to produce orchid-like volatile 1R, 2R-MeJA in vitro. Volatile 1R, 2R-MeJA was detected by gas chromatography–mass spectrometry during the shaking process of oolong tea, and the accumulation of 1R, 2R-MeJA was found to correlate with CsJMT expression. Further investigation showed that the mechanical injury and low-temperature stress could significantly induce CsJMT expression and MeJA accumulation after harvest. These results demonstrated that CsJMT catalyzed the production of MeJA in tea plants and provided a basis for studying the formation and accumulation of orchid-like volatile MeJA during the shaking process of oolong tea.

No place to run

Plants never had it easy. When their ancestors colonized the land about 460 M years ago during the Ordovician period, they were immediately followed by crustaceans—which eventually developed into insects—that found plants a ready source of food. Ever since plants have been at the bottom of the food chain for pathogens and predators from viruses to mammalian herbivores. Unlike animals, plants cannot run away, having given up motility to maximize their surface exposed to sunlight. In lieu, they became masters in chemical warfare and communication to recognize and fend off pathogens and herbivores. Their “claws and teeth” are a dazzling arsenal of chemicals, metabolic and regulatory pathways, producing sensing and communication molecules that attract increasing interest from chemists and biologists for their potential use in medicine and agriculture. > Humans have also learned to use toxic compounds such as digitalis, atropine, opium or nicotine for medicinal, cosmetic or recreational use. Among these molecules are many spices, including the pungent piperine and capsaicin from peppers, or the glucosinolates from mustard and horseradish, and the bitter polyphenols, flavonoids or terpenes from red grapes, coffee beans, tea or cabbage. Humans have long come to appreciate these tastes—that originally evolved as a warning signal to herbivores—for centuries, spices were the most valuable commodity in global trade. Humans have also learned to use toxic compounds such as digitalis, atropine, opium or nicotine for medicinal, cosmetic or recreational use. The alkaloid taxol from the bark of the Pacific yew is a potent chemotherapeutic drug for cancer treatment; artemisinin, isolated from the plant Artemisia annua, or sweet wormwood, has long been employed in Chinese herbal medicine and been refined into a treatment for malaria. The metabolic pathways of plant compounds with medicinal value are therefore an active field of research with the objective of engineering these into E. coli or …

Volatile methyl jasmonate is a transmissible form of jasmonate and its biosynthesis is involved in systemic jasmonate response in wounding

Volatile organic compounds (VOCs) easily diffuse due to their high hydrophobicity. Because of this physical property, VOCs are able to act as crucial signalling molecules mediating intercellular and interplant communication. Methyl jasmonate (MeJA) is a volatile ester form of jasmonic acid (JA) that is involved in interplant communication in response to biotic and abiotic stresses. Despite its function in interplant communication, the specific role of MeJA in the regulation of intercellular jasmonate responses have been poorly understood. In this study, we demonstrated that MeJA is much more effective than JA in inducing jasmonate response, and the higher efficacy of MeJA relies on its volatile property. To understand the function of MeJA in the regulation of the jasmonate response, we analysed function of JMT gene, Jasmonic acid Methyl Transferase using its knockout mutant (jmt) and overexpressing plants (35S:JMT). Mutant plants that lack JMT expression exhibited reduced jasmonate response, while JMT-overexpressing plants exhibited a higher jasmonate response to JA treatment compared to wild-type plants. In this study, we also showed that JMT is specifically expressed in the phloem, the main vascular system for the transport of phytohormones, and that JMT expression affects systemic jasmonate response in wounding. These results suggest the volatile MeJA is a transmissible form of jasmonate and that its biosynthesis is involved in systemic jasmonate response in wounding.

Effects of systemic potato response to wounding and jasmonate on the aphid Macrosiphum euphorbiae (Sternorryncha: Aphididae)

AbstractPlant induced responses are activated by multiple biotic and abiotic stresses, and may affect the interactions between a plant and phytophagous insects. The objective of this work was to evaluate the effects of different stresses inflicted to potato plants (Solanum tuberosum) on the potato aphid (Macrosiphum euphorbiae). Abiotic wounding, biotic wounding by Leptinotarsa decemlineata and treatment with volatile methyl jasmonate (MeJA) were evaluated with regard to the orientation behaviour, the feeding behaviour and the development of the potato aphids. Dual‐choice olfactometry showed that plants treated with MeJA lost their attractiveness for the potato aphids, while both abiotic and biotic wounding did not alter the orientation of aphids. Electropenetrography revealed that the feeding behaviour of aphids was only slightly disturbed by a previous L. decemlineata wounding, while it was highly disturbed by mechanical wounding and MeJA treatment. Aphid nymph survival was reduced on mechanically wounded plants, the pre‐reproductive period was lengthened and the fecundity reduced on plants treated with MeJA. Our results bring new information about the effects of various stresses inflicted to S. tuberosum on M. euphorbiae. We showed that wounding and MeJA treatment induced an antixenosis resistance in potato plants against M. euphorbiae, which may influence aphid colonization processes.

Volatile 1-octen-3-ol induces a defensive response in Arabidopsis thaliana

1-Octen-3-ol is a major volatile metabolite produced by mold fungi. When Arabidopsis plants were treated with 1-octen-3-ol, some defense genes that are turned on by wounding or ethylene/jasmonic acid signaling were induced. The treatment also enhanced resistance of the plant against Botrytis cinerea. When the induction of defense genes with 1-octen-3-ol was compared with that by volatile methyl jasmonate (MeJA) and methyl salicylate treatments, the induction pattern was similar to that caused by MeJA. Thus, Arabidopsis seems to recognize 1-octen-3-ol and consequently activates its defense response.

Lepidopteran herbivory and oral factors induce transcripts encoding novel terpene synthases in Medicago truncatula

Terpenes are an important class of defense compounds that accumulate in plants after pathogen infection or arthropod injury. Sequences predicted to encode terpene synthases were selected from an expressed sequence tag (EST) database of Medicago truncatula. Four putative terpene synthase clones (MtTps1-MtTps4), originating from a chewing insect-damaged M. truncatula leaf cDNA library, were isolated. Transcript levels of each gene examined increased in response to artificial wounding, Spodoptera exigua herbivory, and treatment with volatile methyl jasmonate (meJA). Addition of S. exigua regurgitant to wound sites triggered transcript accumulation of MtTps1 and levels increased with higher concentrations of regurgitant. Furthermore, induction of MtTps1 occurred after application of N-linolenoyl-glutamate or N-linoleoyl-glutamate, factors found in lepidopteran regurgitant. Genomic DNA blots indicate that each of the putative proteins is encoded by a single-copy gene or a small gene family. Proteins encoded by MtTps3 and MtTps4 are imported into the soluble fraction of chloroplasts in in vitro assays, whereas proteins encoded by MtTps1 and MtTps2 are not imported into chloroplasts. Combined with sequence comparisons of multiple plant terpene synthases, the import data indicate that MtTps1 and MtTps2 likely encode sesquiterpene synthases and that MtTps3 and MtTps4 encode mono- or di-terpene synthases. In addition to serving as a valuable model legume species for genomic studies, M. truncatula should prove a valuable source of novel terpene-producing enzymes. Induction of wound-responsive genes by insect oral factors suggests that M. truncatula senses biotic damage through the presence of elicitors originating in the herbivore.

Plant–Plant Signaling: Application of trans- or cis-Methyl Jasmonate Equivalent to Sagebrush Releases Does Not Elicit Direct Defenses in Native Tobacco

Nicotiana attenuata plants growing in close proximity to damaged sagebrush (Artemisia tridentata ssp. tridentata) suffer less herbivory than plants near undamaged sagebrush. Sagebrush constitutively releases methyl jasmonate (MeJA), a compound that when applied directly to N. attenuata, elicits herbivore resistance and the direct defense traits [protease inhibitors (PIs), nicotine]. Damage increases the release of volatile MeJA, primarily in the cis epimer, suggesting that cis-MeJA may mediate this apparent interplant signaling. We characterized sagebrush's MeJA plume before and after damage in nature and in the laboratory, and compared the activity of trans- and cis-MeJA in inducing PIs, nicotine, and Manduca sexta resistance in N. attenuata. We used both lanolin applications and aqueous sprays that mimic natural exposures, and we determined the amount of volatilized MeJA required to elicit a nicotine response in open-grown plants. Wounding rapidly and transiently increased cis-MeJA emissions from damaged parts (but not systemically), and the released plume did not rapidly dissipate in nature. cis-MeJA was not consistently more active than trans-MeJA, and the order of exposure (trans- then cis-) did not influence activity. We conclude that volatile MeJA, either trans- or cis-, when applied at levels consistent with those released by sagebrush does not elicit direct defenses in N. attenuata.

Identification and quantification of methyl jasmonate in leaf volatiles of Arabidopsis thaliana using solid-phase microextraction in combination with gas chromatography and mass spectrometry.

Static headspace sampling with solid-phase microextraction has been used in combination with GC-FID and GC-MS for the specific enrichment, identification and quantification of volatile methyl jasmonate secreted by wounded leaves of Arabidopsis thaliana. The microsample method of analysis was found to be precise, accurate, sensitive and rapid. The detection limit of the procedure is 1.5 ppb (approximately 1.3 ng) per injection, which is of adequate sensitivity to detect the natural baseline levels of methyl jasmonate (approximately 10-100 ng/g) present in plant tissues. The method can be applied to most plants, requires a minimum of sample material, and shows the additional advantage that it is suitable for automation and could thus be used for high-throughput screening.

Methyl jasmonate is blowing in the wind, but can it act as a plant–plant airborne signal?

Abstract Interplant communication in nature is beginning to look like a reality with the field demonstration that tobacco plants downwind of damaged sagebrush suffer less herbivory, a response that appears to be mediated by an airborne signal. Sagebrush constitutively releases methyl jasmonate (MeJA), a compound that is highly active in inducing a number of physiological responses in plants. Damage increases the absolute quantity of the MeJA released as well as the proportion of MeJA in the isomeric cis form. Several studies have shown that volatile MeJA, when released in sufficient quantities, can simulate responses elicited by direct MeJA applications. Additionally, the thermodynamically unstable cis isomer, which is responsible for the characteristic jasmine odor, is thought to be the biologically active form of MeJA. To examine the hypothesis that the cis-MeJA release is responsible for the apparent inter-plant communication, we developed methods to: (1) entrain sagebrush constituents in water which preserved the isomeric shift in the MeJA released after damage; (2) chemically manipulate the MeJA trans : cis ratio; and (3) isolate nearly pure cis-MeJA by HPLC. These treatments were applied as aqueous sprays to a natural population of tobacco plants, however, an outbreak of specialist herbivores consumed all treated plants and chemical analysis on previously harvested treated leaf material was inconclusive. The hypothesis is currently being carefully investigated with laboratory experiments.

Methyl jasmonate protects Norway spruce [Picea abies (L.) Karst.] seedlings against Pythium ultimum Trow.

The effect of methyl jasmonate (MeJA) was tested on the resistance of Picea abies seedlings against Pythium ultimum. Treatments with volatile MeJA during 3 days (25 μl 100 l−1air) protected seedlings up to 75%. This effect was unlikely to result from a direct fungitoxic effect of MeJA, as under the same conditions of treatment, growth in vitro of Pythium ultimum was not affected. Observations of possible changes on histological barriers such as lignin deposits showed no differences between control and treated plants. MeJA induced the accumulation of free salicylic acid (SA) in all parts of the seedlings, whereas bound SA only increased in hypocotyls and cotyledons. An increase in chitinase activity was detected in cotyledons already 2 days after exposure to MeJA. The results suggest that MeJA acts by stimulating defence responses of the host plant. No increase in endogenous jasmonic acid was found in spruce seedlings inoculated with Pythium nor MeJA.

Effect of Volatile Methyl Jasmonate on the Oxylipin Pathway in Tobacco, Cucumber, and Arabidopsis

The effect of atmospheric methyl jasmonate on the oxylipin pathway was investigated in leaves of tobacco (Nicotiana tabacum L.), cucumber (Cucumis sativa L.), and Arabidopsis thaliana (L.). Differential sensitivities of test plants to methyl jasmonate were observed. Thus, different concentrations of methyl jasmonate were required for induction of changes in the oxylipin pathway. Arabidopsis was the least and cucumber the most sensitive to methyl jasmonate. Methyl jasmonate induced the accumulation of lipoxygenase protein and a corresponding increase in extractable lipoxygenase activity. Atmospheric methyl jasmonate additionally induced hydroperoxide lyase activity and the enhanced production of several volatile six-carbon products. It is interesting that lipid hydroperoxidase activity, which is a measure of hydroperoxide lyase plus allene oxide synthase plus possibly other lipid hydroperoxide-metabolizing activities, was not changed by methyl jasmonate treatment. Methyl jasmonate selectively altered the activity of certain enzymes of the oxylipin pathway (lipoxygenase and hydroperoxide lyase) and increased the potential of leaves for greatly enhanced six-carbon-volatile production.

Induction of soybean vegetative storage proteins and anthocyanins by low-level atmospheric methyl jasmonate.

Soybean seedlings were exposed to atmospheric methyl jasmonate (MJ) to determine if low levels of this compound could regulate the expression and accumulation of the vegetative storage proteins (VSPs) in soybeans. Low levels of atmospheric MJ induced the accumulation of three VSPs with molecular masses of 27 kDa, 29 kDa, and 94 kDa (vsp27, vsp29, and vsp94, respectively). Atmospheric MJ caused vsp94 to be accumulated in all above-ground organs of the seedling uniformly after just 3 days of exposure. vsp27 preferentially accumulated in shoot tips and primary leaves, whereas vsp29 preferentially accumulated in the cotyledons. In addition to these effects, MJ also induced the biosynthesis of anthocyanins in light-grown seedlings but inhibited anthocyanin biosynthesis in etiolated seedlings. It is concluded that low levels of atmospheric MJ regulate anthocyanin biosynthesis and the organspecific accumulation of VSPs in developing soybean seedlings. The organ-specific differential accumulation may reflect changes in the pattern of nitrogen partitioning between various compounds and/or organs. These results lend substance to the hypothesis that volatile MJ may act as a gaseous messenger or growth regulator in plants.

Pennsylvania builds tunnel at Baltimore

Methyl jasmonate (MeJA), a significant fatty acid derivative, contributes to the main floral aroma of oolong tea. However, in tea plants, the mechanism of MeJA biosynthesis and the enzymes that participate in its formation is still unclear. In this study, the full length of the first jasmonic acid carboxyl methyltransferase (JMT) gene from Camellia sinensis was amplified and the biochemical function of the recombinant C. sinensis JMT (CsJMT) protein was studied after coexpression in Escherichia coli. The recombinant CsJMT protein could transfer the methyl groups to jasmonic acid to produce orchid-like volatile 1R, 2R-MeJA in vitro. Volatile 1R, 2R-MeJA was detected by gas chromatography–mass spectrometry during the shaking process of oolong tea, and the accumulation of 1R, 2R-MeJA was found to correlate with CsJMT expression. Further investigation showed that the mechanical injury and low-temperature stress could significantly induce CsJMT expression and MeJA accumulation after harvest. These results demonstrated that CsJMT catalyzed the production of MeJA in tea plants and provided a basis for studying the formation and accumulation of orchid-like volatile MeJA during the shaking process of oolong tea.