The postharvest application of elicitors is a sustainable strategy to extend fruit shelf life. However, the molecular and physiological outcomes of combinatorial treatments remain poorly understood. This study investigated the individual and combined effects of exogenous melatonin (MT, 100 & micro;mol L-1) and salicylic acid (SA, 100 mg L-1) on the postharvest senescence, reactive oxygen species (ROS) metabolism, and transcriptional profiles of 'Shine Muscat' grapes. Both individual treatments significantly delayed senescence and preserved fruit quality. MT emerged as the most effective standalone modulator for overall visual quality preservation and fortifying the ascorbate-glutathione (AsA-GSH) cycle to mitigate oxidative stress. Conversely, SA was more effective in suppressing pectolytic enzymes (PME; pectin methylesterase, PG; polygalacturonase) to maintain firmness. Transcriptional profiling showed that individual MT or SA applications acted as potent inducers of secondary metabolism, upregulating key genes in the phenylpropanoid and flavonoid pathways, including phenylalanine ammonia-lyase (VvPAL), flavanone 3-hydroxylases (VvF3H1, VvF3H2), and anthocyanidin reductase (VvANR). However, contrary to expected synergy, co-application (SA+MT) failed to yield additive benefits. Endogenous hormone quantification revealed that while individual applications significantly boosted internal pools, coapplication resulted in moderated accumulation of both SA and MT, corroborating the observed transcriptional interference. Consequently, the SA + MT group exhibited a dampened response across key metabolic gene families, including chalcone isomerase (VvCHI), 4-coumarate:CoA ligase (Vv4CL), and chalcone synthase 2 (VvCHS2). These findings establish MT and SA as potent standalone modulators but demonstrate that simultaneous co-application may trigger signal interference and limit metabolic synergy, necessitating precise optimization in dual-elicitor strategies.

Blue light enhances anthocyanin accumulation in grape berries, yet the molecular mechanisms underlying this photoreceptor-mediated process remain partially elucidated. ‘Kyoho’ grapevines were subjected to various light treatments, including monochromatic blue and red light (blue, red, or white) and mixed red-blue light treatments before fruit coloration. Anthocyanin content, transcriptome profiles, and gene expression were analyzed. Blue light most effectively promoted anthocyanin biosynthesis and upregulated structural genes (VvCHS, VvUFGT, VvANS) and the photoreceptor gene (VvCRY2) expression, whose expression was strongly correlated with anthocyanin accumulation. VvCRY2 physically interacts with the E3 ubiquitin ligase VvCOP1, repressing its activity under blue light. VvCOP1 interacts with transcription factors VvHY5 and VvMYBA1 in darkness, suppressing anthocyanin synthesis. Overexpression of VvCRY2 or VvHY5 enhanced anthocyanin accumulation in transgenic grape calli and strawberry fruits under blue light. VvHY5 directly binds to G-box elements in promoters of VvMYBA1, VvCHS, VvUFGT and VvANS, activating their expression via dual-luciferase assay. We propose a mechanistic model wherein blue light-activated VvCRY2 inhibits VvCOP1, releasing VvHY5 to transcriptionally activate anthocyanin biosynthesis genes. This study elucidates the VvCRY2-VvCOP1-VvHY5 module as a central regulatory axis for light-quality-mediated fruit coloration in grape.

Flower bud differentiation in grapevine (Vitis spp.) is a complex, multi-seasonal process that determines yield potential and fruit quality in this perennial woody crop. This review integrates morphological, physiological, hormonal, and molecular perspectives to elucidate the regulatory mechanisms underlying floral initiation, inflorescence primordium formation, and floral organ differentiation. Grapevine buds exhibit a hierarchical structure with primary, secondary, and tertiary components, where reproductive fate is primarily determined by the primary bud during the first growing season, followed by reactivation after dormancy. Flower bud differentiation is tightly coordinated by nutrient availability, particularly the balance between carbon and nitrogen, and by dynamic hormonal interactions, including gibberellins, cytokinins, abscisic acid, and auxins, which collectively govern meristem fate and inflorescence patterning. At the molecular level, floral organ identity is governed by the ABCDE model, MADS-box transcription factors, miRNA modules, and light- and temperature-responsive regulatory networks that integrate environmental cues with internal signals, orchestrating the precise timing and patterning of floral organogenesis. Recent advances in transcriptomics, hormone profiling, and co-expression network analyses have revealed species-specific adaptations in grapevine that link dormancy, bud burst, and flowering. Understanding these mechanisms provides theoretical and practical insights for optimizing viticultural management, improving bud fruitfulness, and enhancing reproductive performance and resilience under variable climatic conditions.

Drought is a major constraint on global grape production, necessitating effective strategies to enhance plant resilience under water limitation. Methyl jasmonate (MeJA) is known to mediate plant stress responses, but its mechanistic role in grapevine drought tolerance remains insufficiently understood. This study investigated the physiological, biochemical, and molecular effects of foliar-applied MeJA (100 µM, every three days) on ‘Summer Black’ grapevines subjected to 21 days of drought stress. MeJA significantly alleviated drought-induced growth inhibition and reduced oxidative damage by lowering malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL). It concurrently enhanced photosynthetic pigments, osmolytes (proline, soluble sugars, and proteins), and antioxidant enzyme activities (APX, CAT, SOD, GPX). MeJA also improved nutrient retention (N, P, K, Mg, Ca, Fe, Cu, Zn) and partially restored the expression of drought-suppressed photosynthesis-related genes (VvRCA, VvRBCS, VvRBCL2, VvGAPDH). Furthermore, it activated drought-responsive transcription factors (VvNIP1.1, VvWRKY3, VvNAC17, VvNAC8) and ABA-related genes (VvSnRK2, VvNCED1, VvABF1, VvPP2C), indicating enhanced stress signaling and metabolic adjustment. Overall, MeJA strengthened drought tolerance through integrated regulatory mechanisms, supporting its potential as a practical treatment to improve grapevine performance under water scarcity.

Carotenoid-derived compounds, particularly norisoprenoids, significantly contribute to fruit aroma in grape (Vitis vinifera). Carotenoid cleavage dioxygenases (CCDs) are key enzymes catalyzing carotenoid degradation in plants. This study systematically identified 13 VvCCD genes in grape and analyzed their expression patterns across various tissues and developmental stages. Results showed that VvCCD1b was significantly up-regulated during fruit ripening, negatively correlating with carotenoid content and positively correlating with norisoprenoid accumulation. Overexpression of VvCCD1b in tobacco leaves and grape berries significantly reduced lutein and β-carotene levels, confirming its role in carotenoid degradation. Further investigation revealed that the MADS-box transcription factor VvSEP3 was highly expressed during late fruit development and positively correlated with VvCCD1b expression. Overexpression of VvSEP3 in tobacco leaves and grape berries similarly decreased carotenoid content and induced CCD1 gene expression. Biochemical assays demonstrated that VvSEP3 localized to the nucleus and directly bound to the VvCCD1b promoter to activate its transcription. These results uncover a novel VvSEP3–VvCCD1b regulatory module that integrates developmental signals with specialized metabolism, providing targets for quality improvement in grape breeding.

This study investigated the tolerance mechanisms of grapevine rootstocks (SO4 and 101-14) to waterlogging stress during 28 days. Waterlogging severely impaired morphological traits (roots, height, stem, leaves) in both. However, SO4 exhibited significantly greater tolerance than the highly sensitive 101-14. Morphologically, SO4 maintained healthy leaves for 14 days (similar to controls), with damage only appearing after 21-28 days, and developed adaptive adventitious roots despite browning. In contrast, 101-14 showed severe leaf damage (etiolation, chlorosis, wilting) by day 14, complete leaf abscission by day 28, and suffered root loss, necrosis, and disintegration. Physiologically and biochemically, SO4 maintained moderate gas exchange (stomatal conductance, transpiration, CO2 uptake, photosynthesis) and better retained photosynthetic characteristics (carotenoids and chlorophyll). SO4 also activated antioxidant processes (SOD, CAT, POD, APX) earlier and more strongly, resulting in controlled levels of malondialdehyde and hydrogen peroxide, indicating lower levels of oxidative damage. Proline and sugars also increased more in SO4. Conversely, 101-14 experienced severe declines in these areas and exhibited the highest MDA/H2O2 levels. A molecular analysis (qPCR) revealed that the distinct tolerance of SO4 involved significantly higher upregulation of seven stress-responsive genes related to anaerobic metabolism (ADH1), ROS homeostasis (RBOH, POD), protein/membrane stabilization (Stress-Induced Protein, LEA), and stress signaling (KEG, CML). This coordinated response underpinned SO4's sustained energy, efficient antioxidants, reduced oxidative damage, chlorophyll retention, and its maintenance of photosynthesis. The limited gene activation in 101-14 aligned with its physiological collapse. Therefore, the SO4 rootstock demonstrates superior adaptive capacity to waterlogging and is recommended for cultivation under such conditions.

Background: The global transcriptome reprogramming in grapevines in response to powdery mildew remains poorly understood, despite its economic implications, especially the new cultivars. Methods: Thus, this study aimed to elucidate these changes through RNA sequencing in 'Yeniang No. 2' grapevine leaves infected with powdery mildew compared to healthy ones. Results: A total of six samples were subjected to transcriptome sequencing, resulting in 36.85 Gb of clean data. A minimum of 5.89 Gb of clean data was generated for each sample, with at least 92.24% of the clean data attaining a quality score of Q30. Clean reads from each sample were aligned to the designated reference genome. The mapping ratio varied between 88.77% and 89.66%. The high-quality sequencing data revealed 1219 differentially expressed genes (DEGs), of which the infection upregulated 790 and downregulated 429. Functional enrichment analyses revealed a significant activation of key defense-related pathways. These included plant-pathogen interaction, phenylpropanoid and flavonoid biosynthesis for creating antimicrobial compounds, glutathione metabolism for reducing oxidative stress, and oxidative phosphorylation for enhanced energy production. This indicates a coordinated, multi-faceted defense strategy. The study also uncovered a complex layer of post-transcriptional regulation, identifying 1883 novel genes and 22,210 alternative splicing events, primarily skipped exons and intron retention. Key hub proteins identified within interaction networks, along with these splicing changes, underscore a sophisticated defense involving transcriptional reprogramming and metabolic shifts. Conclusions: The genes and molecular markers discovered are valuable resources for marker-assisted breeding. Leveraging these findings, particularly hub genes and favorable splice variants, can accelerate the development of new grapevine cultivars with durable resistance to powdery mildew.

Fruit development and ripening are complex, genetically programmed processes that determine yield, quality, and market value in horticultural crops. These processes rely on the precise temporal and spatial coordination of multiple plant hormones that regulate fruit initiation, growth, maturation, and senescence. Rather than acting independently, hormones operate through highly interconnected signaling networks that involve synergistic and antagonistic interactions at the molecular, cellular, and tissue levels. This review provides an integrated molecular perspective on the hormonal regulation of fruit development and ripening, with emphasis on the dynamic roles of auxin, gibberellins, cytokinins, abscisic acid, ethylene, brassinosteroids, jasmonate, and polyamines. We summarize current knowledge on hormone-driven control of fruit set, early growth, and morphology, followed by a detailed discussion of the hormonal promoters and inhibitors that govern ripening in both climacteric and non-climacteric fruits. Particular attention is given to hormonal crosstalk, key transcriptional regulators, and hormone-perception modules that function as central hubs of integration. Insights from transcriptomics, metabolomics, and tissue-specific studies are highlighted to illustrate how hormonal networks fine-tune developmental transitions. Finally, we discuss future perspectives, including high-resolution hormone mapping, integrative multi-omics approaches, and targeted manipulation of hormone pathways using precision breeding and genome editing to improve fruit quality, stress resilience, and postharvest performance.

Cadmium (Cd) contamination in vineyard soils poses a significant threat to viticulture and food security, yet the physiological and molecular mechanisms governing rootstock responses remain insufficiently understood. This study investigated the impact of Cd on six grapevine rootstocks (Kanzhen 3, SO4, 3309 M, 5BB, 101–14, and Beida) to evaluate their tolerance and mitigation potential. Plants were exposed to soil Cd concentrations ranging from 0 to 20 mg kg⁻¹ for 28 days, with morphological, anatomical, and distribution parameters measured. Additionally, to elucidate the molecular basis of differential tolerance, the expression profiles of 14 major stress-responsive genes were analyzed in the contrasting genotypes ‘101–14’ (sensitive) and ‘SO4’ (tolerant) under high-stress conditions (20 mg kg⁻¹). Physiologically, increasing Cd concentrations significantly inhibited plant height, root length, and biomass across all tissues, with accumulation highest in roots. High exposure caused root structural damage and stomatal closure. Molecular analysis revealed a distinct, genotype-dependent transcriptional response; the tolerant ‘SO4’ genotype exhibited a swift, coordinated upregulation of genes essential for antioxidant defense (VvSOD, VvCAT, VvAPX), flavonoid biosynthesis (VvCHS1, VvSTS1), and detoxification (VvGST4, VvABCC1). Conversely, the sensitive ‘101–14’ genotype displayed a constrained transcriptional response with minimal induction of key defense genes. Translocation and bioconcentration factors were consistently below 1, classifying all rootstocks as “metal excluders” suitable for phytostabilization. Among the tested genotypes, ‘SO4’ and ‘3309 M’ were the most effective at limiting Cd uptake. These findings suggest that Cd toxicity is dose-dependent and that the superior tolerance of SO4 is associated with coordinated upregulation of antioxidant and detoxification genes. Consequently, selecting tolerant rootstocks represents a promising strategy for remediation, though further research under fruiting conditions is required to ensure long-term food safety.

Postharvest senescence, pathogens, and chilling injury present major challenges in the grape industry. This review synthesizes evidence on the physiological and molecular mechanisms by which combined exogenous melatonin (MT) and salicylic acid (SA) preserve grape berries quality. During postharvest storage, the MT-SA crosstalk delays senescence by downregulating ethylene biosynthesis and respiration while bolstering antioxidant defenses to mitigate reactive oxygen species. This synergy preserves structural firmness, stimulates nutritional metabolites, and inhibits enzymatic browning. Additionally, the treatment enhances stress resistance through the activation of defense signaling pathways. Despite these theoretical benefits, empirical data remain inconsistent, with some studies showing individual treatments outperforming the combination. This review suggests these discrepancies stem from non-optimized concentration ratios rather than biochemical incompatibility. Future research must prioritize orthogonal experimental designs to identify the precise dose-dependent synergistic thresholds required to maximize the commercial efficacy of this dual-treatment strategy.

Soil salinity severely limits grapevine (Vitis spp.) growth and productivity, yet the mechanisms distinguishing tolerant and sensitive rootstocks remain incompletely understood. We compared the salt-tolerant rootstock 'SO4' with the salt-sensitive 'Beida' under 100 mmol L-1 NaCl for 0, 6, and 12 days. Salinity progressively reduced photosynthetic pigments in both genotypes, although 'SO4' retained higher levels. Salt treatment also increased hydrogen peroxide, malondialdehyde, soluble sugars, soluble proteins, proline, and antioxidant enzyme activities. Compared with 'Beida', 'SO4' showed stronger osmotic adjustment and greater activation of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase. RNA-seq analysis revealed extensive genotype- and time-dependent transcriptional reprogramming, with differentially expressed genes mainly associated with hormone signalling, secondary metabolism, carbon fixation, protein processing, and lipid metabolism. Weighted gene co-expression network analysis identified the MEblack module as positively associated with salt tolerance in 'SO4' but negatively associated with 'Beida'. Within this module, Vitvi01g00735/VvBCA2 and Vitvi07g02043/VvLCB1 were prioritized as candidate hubs based on high module membership, gene significance, and intramodular connectivity. Hub-centred networks linked VvBCA2 to redox regulation, protein homeostasis, defense, and osmotic signalling, whereas VvLCB1 was associated with cell-wall remodelling, methyl metabolism, membrane signalling, and lipid turnover. Transcription-factor families, including MYB, WRKY, AP2/ERF, bHLH, and HSF, were more strongly represented in 'SO4'. Collectively, these findings identify coordinated physiological and transcriptional mechanisms underlying salt tolerance and provide candidate genes for grapevine improvement.

Polyphenols play a crucial role in plant defense against pathogens. This study examined variations in total polyphenol (TP) content from the seeds of six grape cultivars and evaluated their antifungal activity against Botrytis cinerea. Total polyphenol extracts were first tested in vitro for their effects on fungal mycelial growth and spore germination. Among the cultivars, the extract from 'Tano Black' exhibited the strongest fungistatic activity, whereas 'Seneca' was the least effective. All extracts inhibited and delayed B. cinerea spore germination. To validate these findings in vivo, the TP extract was applied to 'Shine Muscat' grape berries, where it significantly suppressed fungal growth post-inoculation. Further analysis revealed that TP treatment elicited a multifaceted defense response in the fruit. Specifically, it enhanced antioxidant capacity by increasing the activities of polyphenol oxidase (PPO) and superoxide dismutase (SOD), while concurrently reducing hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels. In addition, the treatment helped maintain cell wall integrity by reducing the activities of cell wall-degrading enzymes and upregulating a broad range of disease-resistancerelated genes. Collectively, these results demonstrate that grape seed polyphenols inhibit B. cinerea infection by activating the host's innate defense mechanisms, unserscoring their potential as a natural agent for the postharvest control of gray mold in grapes.

Drought stress severely limits grapevine (Vitis spp.) productivity, yet the regulatory mechanisms distinguishing drought-tolerant and drought-sensitive cultivars remain insufficiently understood. In this study, we integrated transcriptomic, metabolomic, physiological, and functional analyses to compare drought responses between the tolerant cultivar ‘Miguang’ and the sensitive cultivar ‘Red Globe’, together with previously generated datasets from ‘Shine Muscat’ and ‘Thompson Seedless’. Compared with sensitive cultivars, tolerant cultivars showed stronger antioxidant capacity, lower lipid peroxidation, and more coordinated changes in pathways related to redox balance, osmotic adjustment, and energy metabolism. In ‘Miguang’, drought responses were associated with activation of the pentose phosphate pathway, accumulation of tricarboxylic acid cycle intermediates, and genotype-specific alternative splicing events affecting metabolic and signaling genes. Comparative analysis across four cultivars identified VvGRIK1 as a conserved drought-responsive regulator associated with redox and bioenergetic homeostasis. Heterologous overexpression of VvGRIK1 in tobacco enhanced drought-related physiological performance by increasing antioxidant enzyme activities and reducing membrane damage. Yeast two-hybrid assays and molecular docking further suggested a potential interaction between VvGRIK1 and VvKING1, a SnRK1-related energy sensor. Together, these findings suggest that the VvGRIK1-SnRK1 module may contribute to drought adaptation by coordinating redox protection and energy homeostasis, providing a candidate regulatory target for future functional studies and grapevine molecular breeding.

Cadmium contamination in vineyard farming is a global concern due to industrial and human activities like fertilizers, pesticides, and proximity to mines and smelters. In vineyard soil, cadmium is found in various forms, including bioavailable and residual. Soil properties, such as pH, organic matter, and clay, significantly influence its availability and movement. Grape variety and rootstock planting significantly alter soil cadmium speciation, increasing active and decreasing stable fractions and achieving stability over time by preventing elevated Cadmium levels. Cadmium makes it harder for grapevines to absorb nutrients and water, slows their growth, and causes oxidative stress. This leads to physiological and molecular responses of adaptation, tolerance, and resistance. Various grape cultivars and rootstocks exhibit distinct adaptations, tolerances, and resistances based on concentration, duration, and genotype. Elevated concentrations of cadmium in grape fruits provide significant food safety concerns. Although grapes are not heavy metal accumulators, they may pose environmental carcinogenic and/or non-carcinogenic risks to humans. Cadmium concentrations in vineyard soils, grapes, wine, and monthly cadmium consumption exceed the Food and Agriculture Organization and World Health Organization's permissible limits. The maintenance of soil at neutral to alkaline pH, use of hyperaccumulator plant straws, intercropping with hyperaccumulating plants and non-hyperaccumulating grape varieties, alongside the application of brassinosteroids, chitosan-putrescine nanoparticles, and putrescine with carbon quantum dots, represents a promising eco-friendly approach to mitigate cadmium absorption and accumulation in grapes and related products. This review enhances our understanding of Cd behavior in vineyard agriculture and stresses the significance of adopting eco-friendly solutions to reduce its influence.

Abiotic stresses are the major factors limiting grape production in the world. They significantly impede grape growth and production. However, during the grape production stage, plant growth regulators play a crucial role in regulating grape developmental progress, especially methyl jasmonate (MeJA). The exogenous MeJA participates in different crop production, gene expression, signaling transduction, natural defense, stress resistance, hormone balance, osmotic regulation, cellular metabolic process, and thermostatic regulation. Grape crop resilience to different abiotic and biotic stresses was overall fascinated by exogenous applications of MeJA. Therefore, in this review, we focus on the MeJA hormone in abiotic stress relief and discovery, application, significance, occurrence, growth via development, stress responses, interaction, molecular modulation, and biological signaling in the grape. Exogenous MeJA in abiotic stress responses explained the physiological change and the signaling pathway has emerged as one of the key plant metabolic processes vs. photosynthetic productivity, playing a substantial role in gene expression, quality parameters, fruit attribution, protein differentiation, cellular programming, and reprogramming, and tolerance mechanism. MeJA hormone has been discovered after a broader study as abiotic stress-responsive methyl jasmonate/Jasmonic acid, which could be a pivotal target not only for grape production but also for other crops.

Grape fruit are harvested in the late summer or early fall and need to be stored at low temperatures to prevent enfeeblement and prolong their shelf-life. This study aimed to determine the effects of abscisic acid (ABA), brassinolide (BR) and ABA + BR (ABR) treatment on the berry quality of 'Shine Muscat' under low temperatures. ABA and BR maintained fruit appearance, cellular structure, weight, firmness. ABR treatments reduced the loss of fruit aroma. Furthermore, the transcriptome and metabolome analysis revealed that ABA, BR, and ABR treatments maintained the quality of fruits during the low temperatures period by influencing chlorophyll metabolism, carotenoid metabolism, flavonoid metabolism, unsaturated fatty acid, and terpene metabolism. These findings identify key genes and metabolites for ABA and BR-induced maintenance of grape fruit quality during cold storage, expanding our understanding of postharvest storage quality maintenance of grape fruit at the transcript and metabolic levels.

Salinity stress significantly limits the growth and development of grapevines. Various salt-tolerant plant genotypes enhance vineyard cultivation and mitigate the damaging effects of salinity stress by improving physio-biochemical and molecular characteristics. Therefore, the rootstocks ‘3309M’, ‘101–14’, and ‘Kangzhen’ were screened for their response under different salt stress concentrations (50, 100, and 200 mmol L⁻1 NaCl) for 18 days under controlled conditions. Salt-treated plants, especially at high concentrations, exhibited leaf etiolation, wilting, chlorosis, necrosis, and leaf abscission, as well as a decrease in plant height, stem diameter, number of internodes, and number of leaves. Salt-treated plants exhibited significant increases in chlorophyll pigments, total conductance to water vapor, total conductance to CO₂, apparent electron transfer rate, variable fluorescence, maximal fluorescence, Mo, Ca, sugar, proline, and protein content. However, P, K, Zn, Mg, Fe, and Cu levels were significantly decreased compared to the control groups. The antioxidant activities significantly increased as a result of salt stress-generated reactive oxygen species. Furthermore, with the rise in salt doses, there were significant alterations in the expression of genes associated with salt stress and ABA level, which were markedly upregulated in rootstock ‘3309M’, followed by ‘101–14’ and ‘Kangzhen’, in comparison to the control groups. Under salt stress, the rootstock ‘3309M’ exhibited superior phenotypic and physiological characteristics, increased antioxidant activities, maintained ion homeostasis, and improved photosynthetic efficiency compared to the 101–14 and ‘Kangzhen’ rootstocks, respectively. The study revealed that ‘3309M’ rootstock exhibits salt stress tolerance, whereas 101–14 demonstrates moderate salt tolerance, and ‘Kangzhen’ is characterized by salt sensitivity.

Anthocyanin methoxylation, a key enzymatic modification catalyzed by anthocyanin O-methyltransferases (AOMTs), significantly influences color stability and intensity in grape berries. However, the molecular mechanisms underlying varietal differences in methoxylation patterns between colored and colorless grape cultivars remain unclear. In this study, we characterized the function and promoter activity of VvAOMT1 across multiple grape varieties. Phylogenetic and structural analyses revealed that AOMT1 was highly conserved among fruit species. Expression profiling demonstrated that AOMT1 transcript levels correlated with anthocyanin accumulation and skin color. Functional assays via transient and stable transformation in tobacco showed that AOMT1 enzymes from both colored and colorless cultivars effectively catalyzed anthocyanin methoxylation when co-expressed with the regulator MYBA1, significantly increasing methoxylated anthocyanin proportions. In vitro enzymatic assays further confirmed the methoxylation activity of AOMT1 toward anthocyanin substrates. Notably, promoter activity assays and electrophoretic mobility shift assays (EMSA) revealed that natural variations in cis-regulatory elements, especially MYB binding sites (MBS), lead to differential promoter activities and MYBA1 transactivation among cultivars, ultimately affecting AOMT1 expression and methoxylated anthocyanin accumulation. These findings elucidate the regulatory mechanism behind anthocyanin methoxylation in grapes and provide insights for molecular breeding aimed at improving fruit color traits.

The present study scrutinized the influence of foliar application of methyl jasmonate on the physiochemical characteristics and antioxidant enzymes of two grapevine rootstocks, ‘SO4’ (high drought tolerance) and ‘101-14’ (low drought tolerance), under drought conditions. The grapevine seedlings were sprayed with methyl jasmonate at 100 µM at 3-day intervals throughout the 28-day drought stress period. The results showed that treating both rootstocks with methyl jasmonate greatly minimized the adverse effects of reactive oxygen species caused by drought. Specifically, methyl jasmonate substantially reduced levels of malondialdehyde, hydrogen peroxide, and ion leakage while increasing photosynthetic pigment levels, soluble carbohydrates, proline, protein, and total phenols content. Additionally, applying methyl jasmonate improved the action of antioxidant enzymes like superoxide dismutase, ascorbate peroxidase, and catalase. This made the membranes of leaves more solid during drought conditions. Methyl jasmonate treatment reduced oxidative damage and improved mineral element (P, K, Mg, Ca, Fe, and Zn) accumulation in the green leaves of treated plants as opposed to the drought-untreated plants. These results were more noticeable in ‘SO4’ compared to ‘101-14’ rootstocks. Based on these results, applying methyl jasmonate at 100 µM to the leaves of grapevines may be considered a novel strategy for mitigating water scarcity in the grapevine production system.