Application Of Methyl Jasmonate Research Articles

Foliar Methyl Jasmonate Application Activates Antioxidant Mechanisms to Counteract Water Deficits and Aluminum Stress in Vaccinium corymbosum L.

Due to climate change, water deficits (WDs) and aluminum (Al) toxicity are increasing, affecting plants, especially crops such as blueberries (Vaccinium corymbosum L.). The application of methyl jasmonate (MeJA) could mitigate these effects. This work aimed to evaluate the effective MeJA dose to overcome oxidative stress provoked by combined WD+Al stress in blueberries. Plants of Al-sensitive (Star) and Al-resistant (Legacy) cultivars were exposed to control (Al at 65 mg/Kg, 80% field capacity), WD+Al (50% field capacity; Al at 1665 mg/Kg), and WD+Al treatment with different foliar MeJA doses (10, 50, and 100 μM) during 7 and 21 days. Data revealed that plants exposed to WD+Al and treated with 50 µM MeJA reduced Al up to 3.2-fold in roots and 2.7-fold in leaves and improved water potential (Ψw) up to 2.5-fold. The sensitive cultivar decreased the relative growth rate under WD+Al, increasing by 1.9-fold with 50 µM MeJA. Under WD+Al stress, all MeJA doses mitigated the decrease in relative water content in Al-resistant cultivars, restoring values like control plants. In the sensitive cultivar, 50 µM MeJA increased photosynthesis (1.5-fold) and stomatal conductance (1.4-fold), without changes in transpiration. Lipid peroxidation decreased (1.2-fold) and increased antioxidant activity (1.8-fold), total phenols (1.6-fold), and superoxide dismutase activity (3.3-fold) under WD+Al and 50 µM-MeJA. It was concluded that the most effective dose to alleviate the WD+Al stress was 50 µM MeJA due to the activation of antioxidants in blueberry plants. Therefore, the MeJA application could be a potential strategy for enhancing the resilience of V. corynbosum exposed to WD+Al stress.

Effects of foliar applications of methyl jasmonate alone or with urea on anthocyanins content during grape ripening

Anthocyanins, the main phenolic compounds responsible for the color of red grapes and wines, exhibit antioxidant and antimicrobial properties and offer various health benefits for humans. Currently, climate change can affect grape quality by causing a decoupling between the technological and phenolic maturities of the grapes. Foliar application of methyl jasmonate (MeJ) and urea (Ur) can be a tool to mitigate the global warming effects in the vineyard. The aim of this work was to study i) the development of anthocyanin content in ‘Tempranillo’ grapes along the ripening process, and ii) the effect of foliar application of MeJ and MeJ+Ur on these phenolic compounds over two vintages (2019 and 2020). Overall, in the first vintage, anthocyanins peaked in their concentrations in the pre-harvest or harvest moments; whereas in the second vintage, the highest contents of these phenolic compounds were reached at harvest time, after that, a maintenance or decreased of their concentrations was observed. In both vintages, non-acylated anthocyanins was the most abundant family of anthocyanins. Foliar application of MeJ+Ur was more effective in enhancing anthocyanin biosynthesis than MeJ treatment, which also increased anthocyanin content compared to control grapes. Therefore, MeJ and Ur foliar treatment could present a synergy in anthocyanin biosynthesis by the plant. Moreover, the impact of these applications varied across vintages, and also the content of anthocyanins in grapes, probably due to different climatological conditions. Consequently, the two foliar treatments, MeJ and MeJ+Ur, could be a suitable tool to increase anthocyanins biosynthesis in grapes, and thus improve grape quality.

Foliar Application of Methyl Jasmonate and Chitosan Improve Growth, Yield, and Quality of Guar (Cyamopsis tetragonoloba L.) Under Water-Deficit Stress.

Guar (Cyamopsis tetragonoloba L.), a summer legume, is becoming increasingly important as an industrial crop due to its high gum and viscosity content. This study investigated the effects of methyl jasmonate (MeJA), chitosan (CH), and their combination on the growth, yield, and quality of guar under irrigation regimes. A greenhouse experiment was conducted using a factorial design to evaluate the effect of foliar spraying with MeJA (5, 25, and 50 µM), CH (100, 150, and 200 mg/L), their combination (25 µM MeJA + 150 mg/L CH), and control on two commercial guar varieties (RGC-986 and BR-2017) under different irrigation regimes (100%, 70%, and 40% field capacity). The results showed that the exogenous application of MeJA and CH, individually and in combination, significantly enhanced various morphological traits and yield components in guar, including plant height, pod characteristics, seed yield, and root development. Additionally, the combination treatments improved seed quality parameters, such as gum percentage and viscosity content. Leaf analysis revealed increased levels of total phenolic content, total flavonoid, and anthocyanin contents. The BR-2017 variety showed superior performance in most morphological and qualitative traits, demonstrating greater resistance to irrigation regimes. It maintained yield and quality characteristics under water-deficit conditions, particularly when treated with 25 µM MeJA and 150 mg/L CH. The highest gum percentage (33.67%) and viscosity (4768.5 cP) were observed in the RGC-986 variety, along with enhanced levels of secondary metabolites. This study provides new insights into how MeJA, CH, and their combination can improve the yield and quality of guar under water deficit stress conditions. The results suggest that the use of these elicitors, especially in combination, represents an innovative strategy for improving guar production and quality, with potential variety-specific responses to water-deficit stress.

Positive association between foliar silicon and extrafloral nectar in Vicia faba with application of methyl jasmonate

Positive association between foliar silicon and extrafloral nectar in Vicia faba with application of methyl jasmonate

Optimization of Cannabinoid Production in Hemp Through Methyl Jasmonate Application in a Vertical Farming System

Optimization of Cannabinoid Production in Hemp Through Methyl Jasmonate Application in a Vertical Farming System

In vitro application of Methyl jasmonate to induce phytochemical production and antioxidant activity in Dracocephalum polychaetum Bornm. cells

In vitro application of Methyl jasmonate to induce phytochemical production and antioxidant activity in Dracocephalum polychaetum Bornm. cells

Methyl jasmonate mitigates Fusarium graminearum infection in wheat by inhibiting deoxynivalenol synthesis.

Methyl jasmonate (MeJA), a plant growth regulator, coordinates a diverse array of physiological responses, including the inhibition of seed germination, modulation of secondary metabolite biosynthesis, and activation of defence responses. The external application of MeJA has been demonstrated to effectively diminish the severity of fungal diseases. Here, we unveil a novel mechanism through which exogenous MeJA alleviates Fusarium head blight (FHB) by inhibiting the synthesis of deoxynivalenol (DON) in Fusarium graminearum, rather than by enhancing the wheat resistance response. MeJA treatment reduced the infection by wild-type F. graminearum in wheat coleoptiles, but exhibited no significant influence on that of the DON-deficient mutant strain (∆Tri5). The production of DON in F. graminearum was significantly inhibited both in vitro and in planta. MeJA affected the expression of genes related to DON biosynthesis, without influencing the formation of toxisomes as observed under microscopic analysis. Exogenous MeJA demonstrated a limited impact on the early genes of plant jasmonic acid signalling pathway, in contrast to the wild-type pathogen strain, which induced the upregulation of these genes. The expression levels of defence marker genes induced by MeJA were notably lower compared to those induced by the pathogen. This study elucidates the molecular mechanisms of MeJA in modulating the wheat-F. graminearum interaction, providing new insights into the development of environmentally friendly strategies against fungi.

Transcriptomic Analysis of the Combined Effects of Methyl Jasmonate and Wounding on Flavonoid and Anthraquinone Biosynthesis in Senna tora.

Jasmonates, including jasmonic acid (JA) and its derivatives such as methyl jasmonate (MeJA) or jasmonly isoleucine (JA-Ile), regulate plant responses to various biotic and abiotic stresses. In this study, we applied exogenous MeJA onto Senna tora leaves subjected to wounding and conducted a transcriptome deep sequencing analysis at 1 (T1), 3 (T3), 6 (T6), and 24 (T24) h after MeJA induction, along with the pretreatment control at 0 h (T0). Out of 18,883 mapped genes, we identified 10,048 differentially expressed genes (DEGs) between the T0 time point and at least one of the four treatment times. We detected the most DEGs at T3, followed by T6, T1, and T24. We observed the upregulation of genes related to JA biosynthesis upon exogenous MeJA application. Similarly, transcript levels of genes related to flavonoid biosynthesis increased after MeJA application and tended to reach their maximum at T6. In agreement, the flavonols kaempferol and quercetin reached their highest accumulation at T24, whereas the levels of the anthraquinones aloe-emodin, emodin, and citreorosein remained constant until T24. This study highlights an increase in flavonoid biosynthesis following both MeJA application and mechanical wounding, whereas no significant influence is observed on anthraquinone biosynthesis. These results provide insights into the distinct regulatory pathways of flavonoid and anthraquinone biosynthesis in response to MeJA and mechanical wounding.

Methyl Jasmonate (MeJA) Promotes the Self-Pollen Tube Growth of Camellia oleifera by Regulating Lignin Biosynthesis

Self-incompatibility (SI) poses a significant reproductive barrier, severely impacting the yield, quality, and economic value of Camellia oleifera. In this study, methyl jasmonate (MeJA) was employed as an exogenous stimulus to alleviate SI in C. oleifera. The research findings revealed that an exogenous dose of 1000 μmol·L−1 MeJA enhanced the germination and tube growth of C. oleifera self-pollen and greatly improved ovule penetration (18.75%) and fertilization (15.81%), ultimately increasing fruit setting (18.67%). It was discovered by transcriptome analysis that the key genes (CAD, C4H) involved in the lignin production process exhibited elevated expression levels in self-pistils treated with MeJA. Further analysis showed that the lignin concentration in the MeJA-treated pistils was 31.70% higher compared with the control group. As verified by pollen germination assays in vitro, lignin in the appropriate concentration range could promote pollen tube growth. Gene expression network analysis indicated that transcription factor bHLH may be pivotal in regulating lignin biosynthesis in response to MeJA, which in turn affects pollen tubes. Further transient knockdown of bHLH (Co_33962) confirmed its important role in C. oleifera pollen tube growth. In summary, the application of MeJA resulted in the stimulation of self-pollen tube elongation and enhanced fruit setting in C. oleifera, which could be associated with the differential change in genes related to lignin synthesis and the increased lignin content.

Methyl salicylate induces endogenous jasmonic acid and salicylic acid in 'Nam Dok Mai' mango to maintain postharvest ripening and quality

Salicylic acid (SA) and jasmonic acid (JA) are indispensable phytohormones whose interaction influences the ripening process in plants. Methyl salicylate (MeSA) and methyl jasmonate (MeJA) have been utilized to elevate the endogenous levels of SA and JA in horticultural products after harvest. However, their ability to preserve mango is uncertain. Individually and combined effects of exogenous MeSA and MeJA on mango ripening quality were investigated. 'Nam Dok Mai' mangoes were fumigated with MeSA, MeJA, and MeSA plus MeJA (MeSAJA) prior to storage for 6 d at 25 °C and 80–85% relative humidity (RH). Fruit ripening attributes, respiration rate, ethylene (ET) production, total phenolics (TP), and malondialdehyde (MDA) were assessed. Endogenous SA and JA levels were measured, as were the activities of lipoxygenase (LOX) and phenylalanine ammonia-lyase (PAL), and the expression of related genes MiPAL, MiICS, and MiLOX. Individual application of MeSA or MeJA preserved the mango quality by reducing ET production, respiration rate, and MDA levels while raising TP shortly after treatment. The ripening quality mirrored the induced SA and JA levels and correlated with the high expression of biosynthetic-related genes (MiPAL, MiICS, and MiLOX). Individual treatments stimulated SA and JA biosynthesis, demonstrating that these phytohormones are functionally connected and interdependent. When combined, MeSAJA caused a tradeoff response and distinct phenotypic outcomes compared to the individual treatments. As a result, MeSA fumigation is a practical method for preserving mango quality after harvest.

Integrated volatile metabolome and transcriptome analyses provide insights into the warm aroma formation elicited by methyl jasmonate in carrot root.

Carrot is a highly significant vegetable cultivated worldwide and possesses a unique aroma with abundant edible and medicinal values. However, it remains largely unknown whether jasmonic acid could regulate aroma formation in carrot. Here, an integrated analysis of the volatile metabolome and transcriptome of carrot roots exposed to different concentrations of methyl jasmonate (MeJA) was performed. The results revealed 1,227 volatile organic compounds and 972 differential accumulated metabolites, with terpenes representing the largest portion. MeJA treatment evidently increased the relative odor activity values as well as the accumulation of most volatile compounds. In addition, 4,787 differentially expressed genes were identified and subjected to function enrichment analysis, indicating a role of terpene biosynthesis and metabolism in response to MeJA application. A network consisting of 4,680 transcription factor-structural pairs that showed highly significant positive correlations was constructed, which may be utilized as genetic targets for examining terpene accumulation and aroma formation elicited by methyl jasmonate. The results from the present work substantially improved our understanding of MeJA-mediated aroma formation in carrot.

Synergistic suppression of grey mold on cut rose flower by combined application of methyl jasmonate and lipopeptides from Bacillus altitudinis

Roses are the most popular cut flowers that are widely used in various occasions and celebrations, yet can also be easily infected by grey mold caused by Botrytis cinerea; a notorious pathogen in the cut flower industry. A wide range of methods, including fungicides, have been used to control B. cinerea. Environmentally benign methods are increasingly sought after to minimize disease incidence. In this study, we evaluated 10 strains of Bacillus across eight species for their action against B. cinerea. Strains TM22A (Bacillus altitudinis) and S2 (Bacillus subtilis) were identified to be effective in disease suppression. Lipopeptides (LPs) were isolated from two strains, and their activity for inhibiting the growth of B. cinerea was tested. Additionally, methyl jasmonate (MeJA), a natural growth regulator, was evaluated for disease suppression using a in planta assay. Subsequently, LPs from TM22A and MeJA, alone or in combination, were evaluated for disease occurrence in cut rose flowers. Results showed that either LPs or MeJA at concentrations of 250 μmol/L significantly reduced lesion size and disease incidence. The combined application of LPs from TM22A with MeJA further reduced the disease occurrence in cut rose flowers. Furthermore, the activities of POD, PPO, PAL, CAT, and SOD enzymes were much higher in flowers treated with combined application of LPs from TM22A with MeJA. The enhanced suppression of B. cinerea is attributed to the antifungal effects of LPs and MeJA and activation of antioxidant enzymes. This study suggests that the combined application of LPs from TM22A with MeJA could be an environmentally friendly approach for control of grey mold disease in cut roses.

Methyl jasmonate induced tolerance effect of Pinus koraiensis to Bursaphelenchus xylophilus.

Methyl jasmonate (MeJA) can affect the balance of hormones and regulate the disease resistance of plants. Exploring the application and mechanism of MeJA in inducing the tolerance of Pinus koraiensis to pine wood nematode (PWN) infection is of great significance for developing new strategies for pine wilt disease control. Different concentrations (0.1, 1, 5 and 10 mm) of MeJA treatment groups showed differences in relative tolerance index and relative anti-nematode index of P. koraiensis seedlings to PWN infection. The treatment of 5 mm MeJA solution induced the best tolerance effect, followed by the 1 mm MeJA solution. Transcriptome analysis indicated that many plant defense-related genes upregulated after treatment with 1, 5 and 10 mm MeJA solutions. Among them, genes such as jasmonate ZIM domain-containing protein, phenylalanine ammonia-lyase and peroxidase also continuously upregulated after PWN infection. Metabolome analysis indicated that jasmonic acid (JA) was significantly increased at 7 days postinoculation with PWN, and after treatment with both 1 and 5 mm MeJA solutions. Integrated analysis of transcriptome and metabolome indicated that differences in JA accumulation might lead to ubiquitin-mediated proteolysis, and expression changes in trans-caffeic acid and trans-cinnamic acid-related genes, leading to the abundance differences of these two metabolisms and the formation of multiple lignin and glucosides. MeJA treatment could activate the expression of defense-related genes that correlated with JA, regulate the abundance of defense-related secondary metabolites, and improve the tolerance of P. koraiensis seedlings to PWN infection. © 2024 Society of Chemical Industry.

Promoter of COR2-like gene is a stress inducible regulatory region in banana.

A promoter is a crucial component in driving the expression of a transgene of interest for biotechnological applications in crop improvement and thus characterization of varied regulatory regions is essential. Here, we identified the promoter of COR2-like (codeinone reductase-like) from banana and characterized its tissue specific and stress inducible nature. MusaCOR2-like of banana is closely related to COR2 and CHR (chalcone reductase) sequences from different plant species and contains signature sequences including a catalytic tetrad typical of proteins with aldo-keto reductase activity. Transcript level of MusaCOR2-like was strongly induced in response to drought, salinity and exposure of signaling molecules such as abscisic acid, methyl-jasmonate and salicylic acid. Induction of MusaCOR2-like under stress strongly correlated with the presence of multiple cis-elements associated with stress responses in the PMusaCOR2-like sequence isolated from Musa cultivar Rasthali. Transgenic tobacco lines harbouring PMusaCOR2-like-GUS displayed visible GUS expression in vascular tissue of leaves and stem while its expression was undetectable in roots under control conditions. Exposure to drought, salinity and cold strongly induced GUS expression from PMusaCOR2-like-GUS in transgenic tobacco shoots in a window period of 3H to 12H. Applications of salicylic acid, methyl-jasmonate, abscisic acid and ethephon also activate GUS in transgenic shoots at different period, with salicylic acid and abscisic acid being the stronger stimulants of PMusaCOR2-like. Using PMusaCOR2-like-GUS fusion and expression profiling, the current study sheds insights into a complex regulation of COR2-like, one of the least studied genes of secondary metabolite pathway in plants.

Preharvest methyl jasmonate application delays cell wall degradation and upregulates phenolic metabolism and antioxidant activities in cold stored raspberries

The effects of preharvest methyl jasmonate (MeJA) spray application on the physicochemical quality, metabolism of phenolics, and cell wall components in raspberries were investigated during a 10-day cold storage period. MeJA spray reduced firmness loss, decay incidence, and weight loss, while maintained higher levels of soluble solids content, ascorbic acid, anthocyanins and flavonoids in raspberries. Furthermore, MeJA application resulted in increased total pectin and protopectin levels, as well as lowered water-soluble pectin, and activities of pectin methyl esterase, polygalacturonase and cellulase enzymes. Additionally, MeJA treatment upregulated the phenylpropanoid pathway, leading to higher endogenous phenolics and activities of phenylalanine-ammonia lyase and shikimate dehydrogenase. In conclusion, preharvest MeJA spray application could be adopted to enhance the storage potential of cold-stored raspberries for 10 days by maintaining higher firmness, assuring better physicochemical quality, and increasing phenolic metabolism, while reducing cell wall hydrolysis.

PpBBX32 and PpZAT5 modulate temperature-dependent and tissue-specific anthocyanin accumulation in peach fruit.

Anthocyanins are important compounds for fruit quality and nutrition. The R2R3 MYB transcription factor PpMYB10.1 is known to be critical for regulating anthocyanin accumulation in peach. However, regulatory factors upstream of PpMYB10.1 which control temperature-dependent, cultivar-contrasted and tissue-specific anthocyanin accumulation remain to be determined. In this study, differential anthocyanin accumulation in the outer flesh near the peel (OF) of peach [Prunus persica (L.) Batsch] was observed between cultivars 'Zhonghuashoutao' and 'Dongxuemi', as well as among different storage temperatures and different fruit tissues of 'Zhonghuashoutao'. By cross-comparisons of RNA-Seq data of samples with differential anthocyanin accumulation, transcription factor genes PpBBX32 and PpZAT5 were identified. These were functionally characterized as two positive regulators for anthocyanin accumulation via transient expression and genetic transformation. Various interaction assays revealed that both PpBBX32 and PpZAT5 can directly activate the PpMYB10.1 promoter and meanwhile interact at protein level as a PpZAT5-PpBBX32-PpMYB10.1 complex. Furthermore, the results of in silico analysis and exogenous application of methyl jasmonate (MeJA) indicated that MeJA favored anthocyanin accumulation, while it was also found that anthocyanin accumulation as well as PpBBX32 and PpZAT5 expression correlated significantly with endogenous JA and JA-Ile in different fruit tissues. In summary, PpBBX32 and PpZAT5 are upstream activators of PpMYB10.1, allowing JAs to take part in temperature-dependent and tissue-specific anthocyanin accumulation by modulating their expression. This work enriches the knowledge of the transcriptional regulatory mechanisms for differential anthocyanin accumulation under internal and external factors.

CaWRKY22b Plays a Positive Role in the Regulation of Pepper Resistance to Ralstonia solanacearum in a Manner Associated with Jasmonic Acid Signaling.

As important transcription factors, WRKYs play a vital role in the defense response of plants against the invasion of multiple pathogens. Though some WRKY members have been reported to participate in pepper immunity in response to Ralstonia solanacearum infection, the functions of the majority of WRKY members are still unknown. Herein, CaWRKY22b was cloned from the pepper genome and its function against R. solanacearum was analyzed. The transcript abundance of CaWRKY22b was significantly increased in response to the infection of R. solanacearum and the application of exogenous methyl jasmonate (MeJA). Subcellular localization assay in the leaves of Nicotiana benthamiana showed that CaWRKY22b protein was targeted to the nuclei. Agrobacterium-mediated transient expression in pepper leaves indicated that CaWRKY22b overexpression triggered intensive hypersensitive response-like cell death, H2O2 accumulation, and the up-regulation of defense- and JA-responsive genes, including CaHIR1, CaPO2, CaBPR1, and CaDEF1. Virus-induced gene silencing assay revealed that knock-down of CaWRKY22b attenuated pepper's resistance against R. solanacearum and the up-regulation of the tested defense- and jasmonic acid (JA)-responsive genes. We further assessed the role of CaWRKY22b in modulating the expression of JA-responsive CaDEF1, and the result demonstrated that CaWRKY22b trans-activated CaDEF1 expression by directly binding to its upstream promoter. Collectively, our results suggest that CaWRKY22b positively regulated pepper immunity against R. solanacearum in a manner associated with JA signaling, probably by modulating the expression of JA-responsive CaDEF1.

Differential response of roots and leaves to combined heat and salinity stresses in tomato plants

Despite our understanding of plant responses to single stresses, knowledge on how plants respond to combined abiotic factors and the underlying hormonal regulation is still very limited. Here, we aimed to examine the plant response to combined heat and salt stresses in tomato plants, the underlying hormonal response and the effectiveness of methyl jasmonate application in its alleviation. We measured fruit production and various stress markers in both roots and leaves, together with endogenous contents of stress-related phytohormones (including abscisic acid, salicylic acid and jasmonates) in tomato plants (Solanum lycopersicum cv. Micro-Tom), exposed to combined stress. In addition, we evaluated the effectiveness of a methyl jasmonate treatment as a priming agent to alleviate the negative effects of stress, with an emphasis on evaluating the effects of this hormone on triggering antioxidant protection by enhancement of vitamin E contents. Plants responded differently to combined stress treatment than to single stresses, but this differential response was organ-specific, with roots being more sensitive to stress than leaves. Both abscisic acid and jasmonates were involved in the plant response to combined stress but leaves and roots responded differently. Furthermore, abscisic acid and jasmonates correlated with vitamin E accumulation, most particularly in roots. Foliar application of methyl jasmonate at the flowering stage in plants challenged with combined stress did not improve fruit production but resulted in enhanced vitamin E accumulation in leaves. It is concluded that (i) roots and leaves show a differential sensitivity to both single and combined heat and salt stresses, (ii) the response of abscisic acid and jasmonates in plant stress responses seems to be markedly organ dependent, and (iii) foliar methyl jasmonate increased vitamin E accumulation under combined stress in tomato plants.

Jasmonate-insensitive mutant jar1b prevents petal elongation and flower opening coupling with parthenocarpic fruit development in Cucurbita pepo

Jasmonates are growth regulators that play a key role in flower development, fruit ripening, root growth, and plant defence. The study explores the coordination of floral organ maturation to ensure proper flower opening for pollination and fertilization. A new mutant (jar1b) was discovered, lacking petal elongation and flower opening but showing normal pistil and stamen development, leading to parthenocarpic fruit development. The mutation also enhanced the elongation of roots while reducing the formation of root hairs. BSA sequencing showed that jar1b is a missense mutation in the gene CpJAR1B, which encodes the enzyme that catalyzes the conjugation between JA and the amino acid isoleucine. The loss of function mutation in CpJAR1B produced a deficiency in biologically active (+) -7-iso-jasmonoyl-L-isoleucine (JA-Ile), which was not complemented by the paralogous gene CpJAR1A or any other redundant gene. Exogenous application of methyl jasmonate (MeJA) demonstrated that jar1b is partially insensitive to JA in both flowers and roots. Further experimentation involving the combination of JA-Ile deficient and ethylene-deficient, and ET insensitive mutations in double mutants revealed that CpJAR1B mediated ET action in female petal maturation and flower opening, but JA and ET have independent additive effects as negative regulators of the set and development of squash fruits. CpJAR1B also regulated the aperture of male flowers in an ethylene-independent manner. The root phenotype of jar1b and effects of external MeJA treatments indicated that CpJAR1B has a dual role in root development, inhibiting the elongation of primary and secondary roots, but promoting the formation of root hairs.

Methyl jasmonate advances fruit ripening, colour development, and improves antioxidant quality of ‘Yoho’ and ‘Jiro’ persimmon

Methyl jasmonate (MJ) has potential to regulate fruit ripening and quality. ‘Yoho’ and ‘Jiro’ persimmons were sprayed with MJ (0, 2, 4, and 6 mM), four weeks before anticipated harvest to evaluate its effects on fruit colour and bioactive compounds. Preharvest MJ application significantly improved fruit colour with increased a*, b*, chroma, and colour index. The MJ 6 mM application had significantly enhanced soluble solids content (SSC), reduced total chlorophyll content in peel and pulp, and soluble and total tannins in persimmons. MJ treatments exhibited higher contents of total phenolics, flavonoids, carotenoids, and antioxidant activities. Additionally, MJ treatments enhanced the activities of shikimate dehydrogenase (SKDH), phenylalanine ammonia-lyase (PAL), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and lipoxygenase (LOX) enzymes. Overall, pre-harvest MJ application at 6 mM four weeks before anticipated harvest could be useful for advancing colour and improving bioactive compounds in ‘Yoho’ and ‘Jiro’ persimmons.