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Grapes (Vitis sp.) are susceptible to infection by grasshopper and fungus that lead to damaging productivity and economic losses. In this study, we infected the young and old leaf of grapevine by Acrida chinensis and Botrytis cinerea and combined the metabolomic and transcriptomic analysis to comprehend the infection-mediated molecular and metabolic responses. Results indicated that the metabolic reprogramming of lipid, proline, and carbohydrate metabolism is necessary for the biosynthesis of specialized metabolites, which are involved in grapevine defense response. Moreover, the resistance mechanisms of grapevine induced by grasshopper and Botrytis required the hormones crosstalk of abscisic acid (ABA), salicylic acid (SA), ethylene (ETH), brassinosteroid (BR), and jasmonic acid (JA). We also identified the different genes involved in resistance to pathogen and insect attack in transcriptional levels, which encoded pathogenesis-related proteins (PRs), disease resistance proteins (RPS), calcium-binding proteins (CMLs), WRKY transcription factor, abscisic acid-insensitive (ABI), brassinosteroid insensitive 1 (BAK1), ethylene-responsive transcription factor (ERF), leucine-rich repeat receptor-like protein kinases (LRRs), zinc finger protein (ZAT10), chitinase 5, and E3 ubiquitin-protein ligase PUB23 in infected leaves. Furthermore, we nominated various infection-related metabolic biomarkers, including glutathione, proline, aspartyl-L-proline, adenine, histidine, and arginine, that has major effects on the tolerance of leaf-damaging insects and pathogens. Taken together, our research results clarify that there are differences in the defense mechanisms of old leaves and young leaves that lead to different biological stress tolerance and provide deeper insights into grapevine regulatory network mediating defense response against infection caused by grasshopper and B. cinerea, and uncover the resistance mechanisms for functional genomic studies. [ABSTRACT FROM AUTHOR]

Grapes have excellent commercial characteristics and high nutritional value, but postharvest storage inevitably reduces their quality. Previously, we studied the regulatory mechanisms of methylation for grape ripening. To further investigate the effects of epigenetic modifications on postharvest quality of grape berries, Transcriptome deep sequencing (RNA-seq) and metabolome sequencing were performed on 5-Azacytidine (5azaC) or Trichostatin A (TSA) treated grape berries. TSA delayed the depletion of soluble sugar and organic acid content in postharvest grapes compared to controls, while 5azaC had the opposite effect. In addition, TSA and 5azaC affected the content and composition of volatile organic compounds (VOCs) in the berries, of which the decrease in linalool content may be directly responsible for the reduction of muscat flavor in the berries. RNA-Seq analysis showed that 626 and 2253 differentially expressed genes (DEGs) were generated by 5azaC and TSA treatments, respectively. GO and KEGG enrichment analyses revealed significant differences in the biological pathways involved in the two collections of DEGs. Metabolomic analyses further clarified the marker metabolites induced by TSA and 5azaC related to fruit quality. In addition, the results of HDAC activity and transcript levels of acetylation-related genes suggest that VvHDA15 may acetylation modification affects the key regulators of postharvest fruit quality. This study not only provides abundant data information, but also offers new insights into the regulation of fruit quality by epimodification. [Display omitted] • TSA and 5azaC affected sugar, organic acid and aroma in postharvest grapes. • TSA and 5azaC altered gene expression and metabolite levels. • VvHDA15 is a key candidate gene for acetylation regulation of postharvest fruit quality. [ABSTRACT FROM AUTHOR]

Background: Grape buds and leaves are directly associated with the physiology and metabolic activities of the plant, which is monitored by epigenetic modifications induced by environment and endogenous factors. Methylation is one of the epigenetic regulators that could be involved in DNA levels and affect gene expression in response to stimuli. Therefore, changes of gene expression profile in leaves and bud through inhibitors of DNA methylation provide a deep understanding of epigenetic effects in regulatory networks. Results: In this study, we carried out a transcriptome analysis of 'Kyoho' buds and leaves under 5-azacytidine (5-azaC) exposure and screened a large number of differentially expressed genes (DEGs). GO and KEGG annotations showed that they are mainly involved in photosynthesis, flavonoid synthesis, glutathione metabolism, and other metabolic processes. Functional enrichment analysis also provided a holistic perspective on the transcriptome profile when 5-azaC bound to methyltransferase and induced demethylation. Enrichment analysis of transcription factors (TFs) also showed that the MYB, C2H2, and bHLH families are involved in the regulation of responsive genes under epigenetic changes. Furthermore, hormone-related genes have also undergone significant changes, especially gibberellin (GA) and abscisic acid (ABA)-related genes that responded to bud germination. We also used protein-protein interaction network to determine hub proteins in response to demethylation. Conclusions: These findings provide new insights into the establishment of molecular regulatory networks according to how methylation as an epigenetic modification alters transcriptome patterns in bud and leaves of grape. [ABSTRACT FROM AUTHOR]

In recent years, more and more reports have shown that the miR156-SPL module can participate in the regulation of anthocyanin synthesis in plants. However, little is known about how this module responds to hormonal signals manipulating this process in grapes. In this study, exogenous GA, ABA, MeJA, and NAA were used to treat the 'Wink' grape berries before color conversion, anthocyanin and other related quality physiological indexes (such as sugar, aroma) were determined, and spatio-temporal expression patterns of related genes were analyzed. The results showed that the expression levels of VvmiR156b/c/d showed a gradually rising trend with the ripening and color formation of grape berries, and the highest expression levels were detected at day 28 after treatment, while the expression level of VvSPL9 exhibited an opposite trend as a whole, which further verifies that VvmiR156b/c/d can negatively regulate VvSPL9. Besides, VvmiR156b/c/d was positively correlated with anthocyanin content and related genes levels, while the expression pattern of VvSPL9 showed a negative correlation. Analysis of promoter cis-elements and GUS staining showed that VvmiR156b/c/d contained a large number of hormone response cis-elements (ABA, GA, SA, MeJA, and NAA) and were involved in hormone regulation. Exogenous ABA and MeJA treatments significantly upregulated the expression levels of VvmiR156b/c/d and anthocyanin structural genes in the early stage of color conversion and made grape berries quickly colored. Interestingly, GA treatment downregulated the expression levels of VvmiR156b/c/d and anthocyanin structural genes in the early color-change period, but significantly upregulated in the middle color-change and ripening stages, therefore GA mainly modulated grape berry coloring in the middle- and late-ripening stages. Furthermore, NAA treatment downregulated the expression levels of VvmiR156b/c/d and anthocyanin structural genes and delayed the peak expression of genes. Meanwhile, to further recognize the potential functions of VvmiR156b/c/d, the mature tomato transient trangenetic system was utilized in this work. Results showed that transient overexpression of VvmiR156b/c/d in tomato promoted fruit coloring and overexpression of VvSPL9 inhibited fruit coloration. Finally, a regulatory network of the VvmiR156b/c/d-VvSPL9 module responsive to hormones modulating anthocyanin synthesis was developed. In conclusion, VvmiR156b/c/d-mediated VvSPL9 participated in the formation of grape color in response to multi-hormone signals. [ABSTRACT FROM AUTHOR]

• Chitosan treatment disrupts mycelial growth of Botrytis cinerea. • Chitosan treatment improves antioxidant enzyme activity in grape fruits. • Chitosan treatment inhibits the damage of Botrytis cinerea to grape fruit. • Chitosan regulated the signal transduction and metabolite synthesis of grape fruit. Chitosan has a broad-spectrum antimicrobial activity and has been used to control or delay postharvest decay of fruit. In this study, transcriptomic and metabolomics analyses were used to evaluate the effect of chitosan treatment on the resistance to Botrytis cinerea of two grape varieties ('Kyoho' and 'Shine Muscat') that differ in their resistance to this pathogen. Meantime, the effect of chitosan treatment on B. cinerea mycelium growth was analyzed by scanning electron microscope. The physiological indicators of disease and antioxidant enzyme activities of grape fruit after chitosan treatment were also measured. The results showed that chitosan treatment inhibited the damage of B. cinerea to grape fruit. At same time, chitosan could destroy the mycelium of B. cinerea and increase the antioxidant enzyme activities of grape fruit. The differentially expressed genes (DEGs) from treated or non-treated samples with chitosan were mainly enriched in the recognition of fungal diseases, plant hormone biosynthesis and signal transduction, and secondary metabolism. We detected a large number of secondary metabolites using the metabolome that were different in 'Kyoho' and 'Shine Muscat', such as epigallocatechin gallate, catechin, resveratrol etc. In conclusion, chitosan treatment improved disease resistance of grape fruit, and we established a possible model for chitosan regulating disease resistance of 'Kyoho' and 'Shine Muscat'. We found that the expression of DEGs in disease perception, plant hormone biosynthesis and signal transduction, and secondary metabolism differ between 'Kyoho' and 'Shine Muscat' after chitosan treatment, which helps to clarify the possible mechanism of chitosan providing tolerance to B. cinerea. [ABSTRACT FROM AUTHOR]