Concentrations Of Methyl Jasmonate Research Articles

Transcriptome analysis of Artemisia argyi following methyl jasmonate (MeJA) treatment and the mining of genes related to the stress resistance pathway.

Artemisia argyi Lev. et Vant. (A. argyi) is a perennial grass in the Artemisia family, the plant has a strong aroma. Methyl jasmonate (MeJA) is critical to plant growth and development, stress response, and secondary metabolic processes. The experimental material Artemisia argyi was utilized in this study to investigate the treatment of A. argyi with exogenous MeJA at concentrations of 100 and 200μmol/L for durations of 9 and 24h respectively. Transcriptome sequencing was conducted using the Illumina HiSeq platform to identify stress resistance-related candidate genes. Finally, a total of 102.43Gb of data were obtained and 162,272 unigenes were identified. Differential analysis before and after MeJA treatment resulted in the screening of 20,776 differentially expressed genes. The GO classification revealed that the annotated unigenes were categorized into three distinct groups: cellular component, molecular function, and biological process. Notably, binding, metabolic process, and cellular process emerged as the most prevalent categories among them. The results of KEGG pathway statistical analysis revealed that plant hormone signal transduction, MAPK signaling pathway-plant, and plant-pathogen interaction were significant transduction pathways in A. argyi's response to exogenous MeJA-induced abiotic stress. With the alteration of exogenous MeJA concentration and duration, a significant upregulation was observed in the expression levels of calmodulin CaM4 (ID: EVM0136224) involved in MAPK signaling pathway-plant and auxin response factor ARF (ID: EVM0055178) associated with plant-pathogen interaction. The findings of this study establish a solid theoretical foundation for the future development of highly resistant varieties of A. argyi.

Exogenous methyl jasmonate affects genes involved in monoterpene biosynthetic pathway, phyto-biochemical accumulation, and enzymatic activity of Satureja hortensis L.

Satureja hortensis L. (SH) is a medicinal and aromatic herb utilized markedly in the food, pharmaceutical, and cosmetic industries because of its specific secondary metabolites (SMs), especially monoterpenoids. However, the impact of elicitors on the expression of monoterpene synthase genes in SH remains unexplored. Therefore, the supreme objective of this research was to elucidate the phyto-biochemical and targeted genes expression responses of SH to the exogenous application of methyl jasmonate (MeJA). Accordingly, having chosen four concentrations of MeJA, they sprayed at the five-leaf stage for two weeks, and then leaves were harvested at two exposure times of 24 and 48 hrs for further analysis, using spectrophotometric, real time-quantitative polymerase chain reaction (RT-qPCR), and gas chromatography−mass spectrometric (GC–MS) methods. The results highlight that not only were the highest contents of phenolic, flavonoids, peroxidase, superoxide dismutase, proline, and malondialdehyde in the elicited SHs but also the highest expression of β-farnesene synthase (BFS) and 1-deoxy-D-xylulose 5-phosphate reductase (DXR) genes together with the highest amount of carvacrol were up-regulated in them compared to their respective control. In conclusion, these findings demonstrate the great industrial potential of MeJA in improving the production of phytochemicals in medicinal plants, particularly in SH.

Study on the impact of exogenously applied methyl jasmonate concentrations on Solanum lycopersicum under low temperature stress

BackgroundTo decipher the capability of Methyl Jasmonate (MeJA) in resisting cold stress in Solanum lycopersicum assessment regarding various physiological parameters in response to diverse doses of MeJA was done. Low temperature (LT) were given to the plants with MeJA (J1C, J2C, J3C) or without MeJA (LT) application. MeJA in the form of foliar spray was given before stress, during stress and after stress. Three concentrations of MeJA were used under normal and LT stress conditions that includes of J1 (0.5 µM), J2 (10 µM), and J3 (15 µM).ResultsOxidative stress, growth characteristics, stress tolerance parameters, antioxidant response and photosynthetic parameters were investigated. In our current study we observed that oxidative stress markers declined by MeJA supplementation under cold stress conditions. MeJA boosted antioxidant enzyme activity along with photosynthetic parameters. The best concentration of MeJA was J2 based on results obtained. This is the first study related to MeJA best dose screening in Solanum lycopersicum under LT stress conditions.ConclusionThe LT stress in the Solanum lycopersicum plant was reduced by MeJA. The adverse consequences of LT stress can be significantly attenuated by the J2 concentration of MeJA. So, the optimal concentration of MeJA supplied exogenously to LT stressed Solanum lycopersicum can be a smart strategy to mitigate harmful impact of LT stress on detox system and overall growth of plant.

Methyl jasmonate and iron oxide nanoparticles act as elicitors to stimulate production of bioactive antioxidants and metabolites in the in vitro callus cultures of Bergenia ciliata (haw.) Sternb

In vitro callus cultures of Berginia ciliata were used to evaluate different ratios of iron oxide nanoparticles and methyl jasmonate for elicitation, with the goal of improving callus morphological features and bergenin biosynthesis. Shoot explants were cultured using MS (Murashige and Skoog) media supplemented with three elicitation concentrations of iron oxide nanoparticles (30, 60, and 90 ug/l) and three elicitation concentrations of methyl jasmonate (50, 75, and 100 uM). The results were compared to the control without elicitor treatment. All the elicitation treatments significantly enhanced the phytochemical contents. In vitro callus elicitation with 75 uM MeJ and 90 ug/l iron oxide nanoparticles proved as the best among tested elicitation concentrations. The elicitation improved the water contents and fresh and dry weights of the callus. The callus elicitation with 90 ug/l iron oxide nanoparticles increased the callus moisture contents by 16%. The elicitation treatments affected callus color traits and improved the callus compactness. Callus elicitation increased the activities of bioactive antioxidants such as phenylalanine ammonia-lyase, superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase. The contents of bergenin, a major phytochemical, were found enhanced under elicitor treatments. Furthermore, contents of total phenolics and flavonoids improved upon elicitation. The in vitro callus elicitation resulted in better antioxidant potential for B. ciliata as assessed through the DPPH free radical scavenging protocol. The callus elicitation with 90 ug/l iron oxide nanoparticles increased DPPH scavenging percentage by 68%. In vitro callus elicitation with iron oxide nanoparticles and methyl jasmonate is an effective measure to enhance bergenin contents and bioactive antioxidants in the callus cultures of B. ciliata.

Impact of paclobutrazol on storage root number and yield of sweet potato (Ipomoea batatas L.)

Increasing storage root number is an important way to improve the yield of sweet potato. Here, two-year field experiments were conducted to study the effect of 0 (CK), 10, 20 and 30 mg kg−1 paclobutrazol (PBZ) on the phytohormones and lignin biosynthesis, and root growth and yield of sweet potato. The current study found that PBZ10 decreased the concentration of phytohormones gibberellin 3 (GA3), indole acetic acid (IAA) and abscisic acid (ABA) in the subterranean stem, whereas increased the concentration of zeatin riboside (ZR) and methyl jasmonate (MeJA), resulting in lower root length, volume and tip number at 3 and 5 days after planting (DAP). At 5 DAP, PBZ10 decreased GA3, MeJA and ABA concentration in adventitious root, and increased IAA and ZR concentrations, resulting in increased root length, volume, tip number and surface area at 10 DAP. By 5–30 DAP, PBZ10 decreased the concentration of GA3 and ABA in potential storage roots and increased the concentration of IAA, ZR and MeJA, thus increasing root number. At 10–20 DAP, PBZ10 decreased the lignin concentration in the potential storage root along with the expression of IbEXP1 and the enzymatic activities of phenylalanine ammonialyase, 4-coumaric acid CoA ligase and peroxidase, which are involved in the regulation of lignin biosynthesis, resulting in increased potential storage root diameter; interestingly, the opposite pattern was observed by 25–30 DAP. Then, PBZ10 increased the SR number at 40 DAP, and the yield of sweet potato at harvest time, and no PBZ was detected in SRs of PBZ10. But excessive concentration of PBZ is unfavorable to root development and led to a decrease of yield. These results indicated that a moderate PBZ (10 mg kg−1) application could reasonably regulate phytohormones and lignin biosynthesis, then increase storage root number and yield of sweet potato.

Effect of stress hormones on the metabolome of a suspension culture of the aromatic medicinal plant Cymbopogon schoenanthus subsp. proximus

The current study aimed to evaluate and compare the effect of different concentrations (0.0–200.0 µM) of jasmonic acid (JA), methyl jasmonate (MeJA), and salicylic acid (SA) on suspension culture mass production and untargeted metabolic profiling of the medicinal plant Cymbopogon schoenanthus subsp. proximus. The addition of 50 µM MeJA improved the fresh weight of embryogenic tissue significantly. MeJA and SA did not affect tissue dry weight, whereas JA significantly decreased it. Based on 1H and 1H–13C NMR data and NMR databases, 50 compounds were identified. The addition of stress hormones resulted in the biosynthesis of novel metabolites like theophylline and syringate that were absent in control samples. In addition, significant variations in the concentrations of numerous compounds, including sugars, amino acids, organic acids, phenols, and alkaloids, were observed. The upregulation of trigonelline concentration was observed upon the addition of a higher concentration of MeJA (200 µM), whereas all tested concentrations of SA resulted in its upregulation. Addition of JA and SA causes significant changes in aminoacyl-tRNA biosynthesis pathway and amino acid metabolism pathways, such as alanine-aspartate and glutamate metabolism and arginine and proline metabolism. MeJA had significant impacts on glycolysis and starch-glucose metabolism pathways in addition to amino acids metabolism pathways. The present findings were successful in demonstrating a correlation and distinction between the effects of JA, MeJA, and SA, on the metabolome of Cymbopogon schoenanthus, a valuable medicinal plant. The identified metabolites and their associated pathways would be valuable in future biotechnology applications of the genus Cymbopogon.

Methyl jasmonate, salicylic acid, and oxalic acid affects growth, inducible defenses, and pine weevil resistance in Norway spruce.

The large pine weevil (Hylobius abietis) is a major regeneration pest in commercial forestry. Pesticide application has historically been the preferred control method, but pesticides are now being phased out in several countries for environmental reasons. There is, thus, a need for alternative plant protection strategies. We applied methyl jasmonate (MeJA), salicylic acid (SA) or oxalic acid (OxA) on the stem of 2-year-old Norway spruce (Picea abies) plants to determine effects on inducible defenses and plant growth. Anatomical examination of stem cross-sections 9 weeks after application of 100 mM MeJA revealed massive formation of traumatic resin ducts and greatly reduced sapwood growth. Application of high concentrations of SA or OxA (500 and 200 mM, respectively) induced much weaker physiological responses than 100 mM MeJA. All three treatments reduced plant height growth significantly, but the reduction was larger for MeJA (~55%) than for SA and OxA (34-35%). Lower MeJA concentrations (5-50 mM) induced comparable traumatic resin duct formation as the high MeJA concentration but caused moderate (and non-significant) reductions in plant growth. Two-year-old spruce plants treated with 100 mM MeJA showed reduced mortality after exposure to pine weevils in the field, and this enhanced resistance-effect was statistically significant for three years after treatment.

Changes in Phytohormone and Antioxidant Enzyme Activities during the Healing Process of Different Crabapple Rootstock–Scion Combinations

By measuring the changes in phytohormones and related enzyme activities of Malus ‘Huabiao’ scions and different rootstocks during the healing process of grafting, this study aims to analyze the effects of different rootstocks on the physiological metabolism of the grafting healing site, thereby providing reference for the selection of M. ‘Huabiao’ grafting rootstocks. The live seedlings of 1-0 M. hupehensis, M. robusta and M. baccata were chosen as rootstocks, and M. ‘Huabiao’ scions were grafted with these seedlings in spring by pasting method. The dynamic changes in activities of indole acetic acid, zeatin riboside, methyl jasmonate content and peroxidase, polyphenol oxidase and L-phenylalanine ammonia-lyase at the healing site of grafting were measured, and the effects of different grafting combinations on the phytohormone and related enzyme activities at the grafted site were investigated. It was found that the M. ‘Huabiao’/M. hupehensis and M. ‘Huabiao’/M. robusta grafting combinations had significantly higher survival rate than M. ‘Huabiao’/M. baccata which only had a success rate of 63%. At the beginning of graft healing, the contents of three phytohormones in healing sites of all the three grafting combinations exhibited a significant decrease. However, in the mid and late stages, great differences were shown in phytohormone content. During the grafting healing process, the changes in three enzyme activities in healing sites of the three grafting combinations showed some regularities. In conclusion, M. hupehensis and M. robusta have strong grafting compatibility with M. ‘Huabiao’; thus, they are suitable to be selected as rootstocks for grafting and propagation of M. ‘Huabiao’. In addition, the changes in phytohormone content and enzyme activity in different grafting combinations reflect the strong affinity relationship between rootstock and scion grafting.

Putrescin modulates metabolic and physiological characteristics of Thymus daenensis under drought stress

This experiment was conducted to understand the protective impact of exogenous putrescine (Put) in Thymus daenensis under drought stress. Plants of T. daenensis were subjected to drought stress (15% polyethylene glycol) and Put (0.2 mM). Drought stress lowered growth attributes and photosynthetic pigments in T. daenensis plants. The increase in the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) as oxidative stress indicators showed that drought stress caused oxidative stress in T. daenensis plants. Drought stress augmented proline content, phenylalanine ammonia-lyase activity, tyrosine ammonia-lyase activity, indole-3-acetic acid content and methyl jasmonate content in T. daenensis plants. Put treatment improved growth and regulated adaptative mechanisms in T. daenensis plants. Decrease in H2O2 and lipid peroxidation (MDA content) by Put displayed that Put helped to alleviate drought-trigged oxidative stress in T. daenensis plants. Put application strengthened the antioxidant system as a resistance response in the drought-treated T. daenensis plants thereby induction in enzymes activities (superoxide dismutase, catalase and peroxidase) and non-enzymatic antioxidants (total phenol and flavonoid). Put treatment increased coumaric acid and resveratrol content in stressed plants. These results propose a multifaceted contribution of Put on adaptative mechanisms in T. daenensis plants under drought stress.

The Impact of Chemical Fertilizer Application on Ascorbic Acid-Glutathione Cycle, Methyl Jasmonate and Nitrosoglutathione Related Substances of Antioxidant Systems in Tobacco

The unreasonable application of chemical fertilizer as abiotic stress can affect the production of reactive oxygen species (ROS) and the synthesis of related substances, thereby affecting the antioxidant systems mediated by Ascorbate-glutathione (AsA-GSH) cycle, Methyl jasmonate (MeJA), S-Nitrosothiols (SNOs) in tobacco plants. Up to now, further research is needed on the impact of chemical fertilizer application on the above antioxidant system in tobacco plants. In this study, the flue-cured tobacco cultivar ‘Yunyan 87’ (Nicotiana tabacum L.) was used as the material. The content of non-enzyme antioxidants and related enzyme activities of AsA-GSH cycle system, the content of MeJA and SNOs in tobacco leaves, as well as tobacco yield were detected, to study the effects of different amount of fertilizer application (T1 = 30 g/plant, T2 = 45 g/plant, T3 = 60 g/plant) on related indicators of antioxidant system. The results indicated that the content of non-enzymatic antioxidants (AsA and GSH) and the activities of related enzymes in the AsA-GSH cycle, including ascorbate peroxidase (APX), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) exhibited first increased and then decreased with increasing amount of fertilizer application. Most of the treatments showed significant differences. T3 treatment markedly reduced MeJA content compared to T1 and T2 treatments. With the increase of fertilizer application, the content of SNOs and the activity of S-Nitrosoglutathione reductase (GSNOR) in tobacco leaves exhibited an initial increase, followed by a decrease, and finally increasing trend, with notable differences among most treatments. Tobacco yield markedly decreased in the T1 treatment compared to the T2 and T3 treatments; however, no obvious difference between T2 and T3 treatments. Altogether, the fertilizer application of T1 (30 g/plant) was too low, which was not conducive to the synthesis of antioxidant substances in tobacco leaves. However, the fertilizer application amount of T3 (60 g/plant) was attributed to excessive application, which caused high salt stress on the growth of tobacco plants. This study provides a basic reference for optimizing fertilizer application in tobacco production.

Methyl jasmonate (MeJA) enhances salt tolerance of okra (Abelmoschus esculentus L.) plants by regulating ABA signaling, osmotic adjustment substances, photosynthesis and ROS metabolism

Methyl jasmonate (MeJA), as a plant growth regulator, which is involves in many morphological and physiological processes, plays an important role in defense systems of plants under stress conditions. However, the roles of physiological and biochemical mechanisms of enhancing salt tolerance of okra plants based on application of MeJA is poorly understood. In this study, the application of the investigated 50 μM MeJA significantly improved salt tolerance of okra plants based on the germination rates and culture pot experiment under salt stress. Based on optimal concentration of MeJA inducing salt tolerance of okra plants, application of 5 mM diphenyleneiodonium (NADPH oxidase inhibitor, DPI) and 50 μM MeJA + 5 mM DPI, respectively, significantly increased salt tolerance of okra plants. Assays on the content of component matter indicated the significant increases of JA, ABA, proline, soluble protein, soluble sugar, photosynthetic pigment and relative water, glutathione (GSH) and ascorbic acid (AsA) content and the significant decreases of hydrogen peroxide (H2O2), superoxide radicals (O2−) and malondialdehyde (MDA) content and electrolyte leakage rates were observed in okra plants with 50 μM MeJA under salt stress. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX) and peroxidase (POD) related to ROS scavenging were also enhanced in okra plants by applied MeJA under salt stress. Furthermore, the marked decreases of H2O2, O2- and MDA content, and the significant increases of CAT, GR and APX activities and GSH and ASA content involved in ASA-GSH cycle were observed in MeJA-okra, DPI-okra and MeJA+DPI-okra plants under salt stress. H2O2 acted a toxic accumulation of ROS rather than as a second messenger for signal transduction in okra plants. These results demonstrate that exogenous MeJA increases the accumulation of JA, ABA and proline, which enhances salt tolerance of okra plants, by regulating osmotic balance and protecting membrane integrity and photosynthesis and activating ROS scavenging system. As a conclusion, treating okra plants with 50 μM MeJA could alleviate the harmful effects of abiotic stresses.

Concentration-dependent impacts of exogenous methyl jasmonate (MeJA) on chlorophyll degradation of apple fruit during ripening

Although jasmonates (JAs) have been proved to regulate degreening of apple fruit, the relevant molecular mechanisms have not yet been clarified. Previous reports revealed that the effects of JAs on degreening of harvested horticultural crops might be dependent on concentration applied. Whether a similar result can be obtained from apple fruit is still unclear. This research explored the impacts of different concentrations of methyl jasmonate (MeJA) treatment on chlorophyll (Chl) degradation of postharvest apple fruit. Apples (Malus × domestica Borkh.) of commercial maturity were treated with 10 or 1500 µM MeJA and then stored at 20 ± 0.5 °C. The results indicated that exogenous 10 µM MeJA delayed degreening and ripening of apple fruit, whereas 1500 µM MeJA treatment had the opposite effects. Treatment with 10 µM MeJA alleviated Chl-oxidation by reducing Chl-peroxidase (POX) activity and reactive oxygen species (ROS) levels in chloroplast of apple peel during ripening, whereas 1500 µM MeJA treatment had the opposite effects. Activities of Magnesium-dechelatase (MDcase) and pheophytinase (PPH) in apple peel were differentially suppressed by 10 µM MeJA treatment while promoted by 1500 µM MeJA treatment during ripening. Application of 10 µM MeJA delayed the peak of endogenous jasmonic acid (JA) content, reduced jasmonate resistant 1 (JAR1) content and allene oxide synthase (AOS) activity, and differentially down-regulated expression of MdNYC3, MdNYE1a, MdPPH1, MdPAO6, MdPAO8, MdRCCR2 and MdMYC2a in apple peel during ripening, whereas opposite results were obtained from the 1500 µM MeJA-treated apple fruit. At the late ripening stage, MdHCAR expression in apple peel was promoted by 10 µM MeJA treatment while reduced by 1500 µM MeJA treatment. Transcript levels of MdNYC1 and MdNOL2 were generally reduced by both treatments at the late ripening stage. Transient overexpression of MdMYC2a accelerated Chl degradation of apple peel by promoting PPH and MDcase activities and enhancing expression of the above Chl catabolic genes (CCGs), except MdHCAR whose expression was down-regulated by it during ripening. The AOS activity, JA and JAR1 contents in apple peel were increased after transient overexpression of MdMYC2a during ripening. These data indicated that the PAO pathway and Chl-oxidation were regulated by JA signal in apple peel during ripening, and exogenous MeJA regulated Chl degradation of apple fruit in a concentration-dependent manner.

The Stimulation of the Anticancer Chemical Taxol in Taxus baccata

Abstract Taxol is an anticancer drug that is widely used in cancer treatment worldwide. Since the source of the drug is a plant, the increase in its production is one of the concerns of researchers. One way to increase the production of Taxol is to use stimulants for secondary metabolite production. Therefore, in this study, methyl jasmonate was used as a bioelicitor, and its effect on Taxol production was evaluated. For this purpose, Taxus baccata was elicited for 48 and 72 hours with concentrations at 0, 100, 250, and 500 μM methyl jasmonate, and the quantities of Taxol in the leaf and stem explants were measured by high-performance liquid chromatography (HPLC). The results showed that among the leaf and stem explants, a tremendous amount of Taxol production is related to the leaf, which is a great advantage in reducing the number of trees cut down to obtain Taxol. In addition, the 48-hour elicitation time demonstrated the best result in the production of Taxol. The optimal concentration of methyl jasmonate was also estimated at 500 μM and 0.326 mg/g of dried leaf biomass. The results of this experiment showed that methyl jasmonate has the potential to be used as a biological elicitor to produce considerable amounts of Taxol in Taxus baccata.

Foliar methyl jasmonate (MeJA) application increased 2-acetyl-1-Pyrroline (2-AP) content and modulated antioxidant attributes and yield formation in fragrant rice

Endogenous methyl jasmonate (MeJA) mediates abiotic and biotic stresses in plants. Exogenous MeJA application can stimulate and defend plant gene expression and induce plant chemical defense. The effects of foliar MeJA application on yield and 2-acetyl-1-pyrroline (2-AP) biosynthesis of fragrant rice are scarcely investigated. The pot experiment was conducted by spraying different concentrations of MeJA (0, 1, and 2 μM; denoted as CK, MeJA-1, and MeJA-2) at the initial heading stage of two fragrant rice cultivars, Meixiangzhan and Yuxiangyouzhan. The results showed that foliar MeJA application significantly increased the grain 2-AP content by 32.1% and 49.7%, respectively, following MeJA-1 and MeJA-2 treatments, and the two cultivars showed the highest 2-AP content upon MeJA-2 treatment. However, the grain yield was increased in MeJA-1 as compared with MeJA-2 treatment for all rice cultivars and no significant differences were observed in yield and yield-related traits compared with CK. The aroma was improved by foliar MeJA application which was strongly associated with the regulation of the precursors and enzymes involved in 2-AP biosynthesis. In particular, the contents of proline, pyrroline-5-carboxylic acid, and pyrroline at maturity, as well as the activities of proline dehydrogenase, ornithine aminotransferase, and pyrroline-5-carboxylic acid synthetase, were positively correlated with grain 2-AP content. On the other hand, foliar MeJA application improved the contents of soluble protein, chlorophyll a and b, and carotenoid, and increased the activity of antioxidant enzymes. Moreover, peroxidase activity and leaf chlorophyll contents were significantly positively correlated to 2-AP content following foliar MeJA application. Therefore, our results implied that foliar MeJA application increased aroma and influenced yield by regulating the physio-biochemistry characters and resistance, and suggested that the optimal concentration of MeJA for the best positive effect on the yield and aroma was 1 μM. However, further study is required to evaluate the metabolic level and molecular basis of the regulatory mechanism of foliar MeJA application on 2-AP in fragrant rice.

Methyl jasmonate treatment alleviates chilling injury and improves antioxidant system of okra pod during cold storage.

Okra pod is sensitive to low temperature, which results in chilling injury under improper low-temperature storage. This study aimed to evaluate the effect of different concentrations of methyl jasmonate (MeJA) treatment on okra pod stored at 4 ± 1°C for 12 days and illuminate the mechanism of MeJA alleviating chilling injury. Compared to the control, MeJA treatments maintained lower relative electric conductivity (REC), chilling injury (CI) degree, and lignin content, as well as higher total soluble solids, total soluble sugar, pectin content, and chlorophyll content. The factor analysis was applied to comprehensively evaluate the effects of MeJA so that 1μmol/L MeJA was screened as the optimum concentration to maintain the okra quality throughout the storage time. In contrast with control, MeJA not only accelerated the generation of antioxidant substances (phenolics and flavonoids) but also increased the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) activity, inhibited malondialdehyde (MDA), hydrogen peroxide (H2O2) content accumulation, and the polyphenol oxidase (PPO) activity. This work confirmed that MeJA could effectively alleviate chilling injury and maintain the quality during cold-stored by regulating reactive oxygen species (ROS) metabolism. These results provide theoretical guidance for the application of MeJA in okra storage and preservation.

Expression Analysis of CoHMGS in Cornus officinalis and Subcellular Localization of the Enzyme It Encodes.

Cornus officinalis is a perennial deciduous tree or shrub. Its mature fruits are extracted and used in Traditional Chinese Medicine, called Shanzhuyu. The characteristic active components of C. officinalis include loganin and morroniside, which belong to iridoid glycosides. 3-Hydroxy-3-methylglutaryl-CoA synthase (HMGS) is a key enzyme in the cytoplasmic mevalonate pathway providing the precursor molecules isopentenyl pyrophosphate and dimethylallyl pyrophosphate for isoprenoid biosynthesis such as sterols, triterpenes, and their derivatives such as iridoid glycosides. Different concentrations of methyl jasmonate (MeJA) and ethephon (ETH) solutions were sprayed on C. officinalis seedlings, and the effect of hormones on CoHMGS gene expression was detected by real-time fluorescence quantitative PCR. The quantitative real-time PCR results showed that 750 mg/L ETH treatment had the most significant induction effect on CoHMGS gene expression. The HPLC analysis of extracts revealed that the treatment could also significantly increase the content of morroniside and loganin in the leaves of C. officinalis. By use of a CoHMGS-green fluorescent protein (GFP) fusion construct for heterologous expression in tobacco, laser scanning confocal microscopy revealed a cytoplasmic localization. This preliminary study of the CoHMGS gene could prepare the ground for more precisely elucidating the synthesis of secondary metabolite in C. officinalis.

Effects of Methyl Jasmonate Fumigation on the Growth and Detoxification Ability of Spodoptera litura to Xanthotoxin.

Methyl jasmonate (MeJA) is a volatile substance derived from jasmonic acid (JA), and it responds to interbiotic and abiotic stresses by participating in interplant communication. Despite its function in interplant communication, the specific role of MeJA in insect defense responses is poorly understood. In this study, we found that carboxylesterase (CarE) activities, glutathione-S-transferase (GSTs) activities, and cytochrome mono-oxygenases (P450s) content increased more after the feeding of diets containing xanthotoxin, while larvae exposed to MeJA fumigation also showed higher enzyme activity in a dose-dependent manner: lower and medium concentrations of MeJA induced higher detoxification enzyme activities than higher concentrations of MeJA. Moreover, MeJA improved the growth of larvae fed on the control diet without toxins and diets with lower concentrations of xanthotoxin (0.05%); however, MeJA could not protect the larvae against higher concentrations of xanthotoxin (0.1%, 0.2%). In summary, we demonstrated that MeJA is effective at inducing S. litura defense response, but the enhanced detoxifying ability could not overcome the strong toxins.

Effect of Methyl Jasmonate Elicitation on Triterpene Production and Evaluation of Cytotoxic Activity of Mycelial Culture Extracts of Ganoderma applanatum (Pers.) Pat.

Abiotic elicitation, a well-known strategy in mushroom biotechnology, promotes increased accumulation of secondary metabolites in mycelial cultures. The study aimed the effects of methyl jasmonate (MeJA) on the production of triterpenes in submerged cultures of Ganoderma applanatum. Further, the study evaluated the cytotoxic activity of the extract corresponding to the optimal elicitation variant in selected human cancer cell lines as well as the selectivity against normal cells. MeJA was added on days 1, 4, 6, and 8 in the 10-day growth cycle at concentrations of 10, 50, 100, 150, and 200 µM MeJA. The HPLC-DAD was used to analyze the triterpenes. The cytotoxic activity was tested using the MTTFc assay in grouped panels of skin, prostate, and gastrointestinal cancer cells. The results of the quantitative analyses confirmed the stimulating effect of MeJA on the production of ganoderic acid A and ganoderic acid C. The greatest increase in total triterpenes was found on day 6 of the culture cycle compared to the control group-with the concentration of MeJA-150 µM. Compared to the control samples, mycelial culture extract after the most productive elicitation variant showed significant cytotoxic activity against prostate cancer cells and moderate effects on melanoma cells. Ganoderma applanatum mycelial cultures can be proposed as a model to study the dynamics of the accumulation of compounds with therapeutic values through abiotic elicitation.

Understanding the Sensitivity of Grape Terpenes to Jasmonates Using In Vitro Culture and In Vivo Vineyard Experiments.

Terpene volatiles define the flavor of terpenic grape cultivars. However, grape terpene concentrations can vary 2- to 3-fold across seasons and vineyards, impacting vintage quality. The plant hormone methyl jasmonate (MeJA) stimulates grape terpene production but is expensive and can decrease berry weight and maturity. The synthetic jasmonate prohydrojasmon (PDJ) is cost-effective yet has not been evaluated on grape maturity and terpene production. Here, we performed in vitro (berry culture) and in vivo (vineyard) experiments using Gewürztraminer (Vitis vinifera L.) to evaluate the time- and concentration-dependent sensitivity of maturity parameters and terpene content to MeJA and PDJ. In vitro berry weight was reduced by high MeJA and PDJ concentration across timings. Terpenes were most sensitive to low MeJA concentration at veraison (increased 24-fold) in vitro. Moderate PDJ concentration applied at veraison doubled (increased twofold) terpene concentration in vivo without impacting berry weight or maturity. In conclusion, PDJ may provide a solution to mitigate seasonal variability in terpene production in terpenic grape cultivars.

Exogenous methyl jasmonate induced cassava defense response and enhanced resistance to Tetranychus urticae

Exogenous application of methyl jasmonate (MeJA) could activate plant defense response against the two-spotted spider mite (TSSM), Tetranychus urticae Koch,in different plants. However, whether MeJA can also serve as an elicitor in cassava (Manihot esculenta Crantz) remains unknown. In this study, induced defense responses were investigated in TSSM-resistant cassava variety C1115 and TSSM-susceptible cassava variety KU50 when applied with MeJA. The performance of TSSM feeding on cassava plants that werepre-treated with various concentrations of MeJA was first evaluated. Subsequently, the activities of antioxidative enzymes (superoxide dismutase and catalase), detoxification enzymes (glutathione S-transferase, cytochrome P450 and carboxylesterase) and digestive enzymes (protease, amylase and invertase) in TSSM were analyzed at days 1, 2, 4 and 8 post-feeding. The results showed that MeJA treatment can induce cassava defense responses to TSSM in terms of reducing egg production and adult longevity as well as slowing development and prolonging theegg stage. Noticeably, C1115 exhibited stronger inhibition of TSSM development and reproduction than KU50. In addition, the activities of all the tested enzymes were induced in both C1115 and KU50, the most in C1115. We conclude that exogenous methyl jasmonate can induce cassava defense responses and enhance resistance to TSSM.