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The stable operation of transformers is an important guarantee of power system security. The temperature distribution of main insulation is different in long‐term operation. The temperature difference between the local hottest spot temperature and the average oil temperature in the transformer exceeds 30 K. Therefore, the oil‐paper insulation inside the transformer will exhibit non‐uniform ageing after long‐term operation. At present, frequency domain dielectric response (FDS) technology is widely used in transformer ageing assessment. However, the existing assessment methods are only used for overall insulation ageing assessment. The average moisture content and polymerization degree of the overall insulation between each phase winding are obtained. But it still cannot be used to assess the non‐uniform ageing of the transformer's main insulation. The radial, axial, and two directions non‐uniform ageing models have been made in the laboratory in this study. The FDS and physicochemical properties of non‐uniform ageing models were tested. The variation law of FDS for non‐uniform ageing models was analysed. Meanwhile, the dielectric relaxation model of non‐uniform ageing for main insulation was established. The method of frequency division iterative calculation was proposed. Combined with the Fessler moisture balance formula of ageing oil‐paper insulation, the quantitative assessment method for ageing parameters of the non‐uniform ageing model can be realized. Compared the calculated results with the chemical analysis results, the relative error of the polymerization degree calculation is less than 4%, and the error of the moisture content calculation is less than 0.3%. The calculation results can meet the needs of the engineering apply. Therefore, this method can realize the quantitative assessment of transformer main insulation ageing, which is of great significance to assess the transformer insulation state. [ABSTRACT FROM AUTHOR]

Leaf morphogenesis in Vitis vinifera is closely associated with the biosynthesis of various metabolites, starch, and growth-related molecules. In the present study, Illumina RNA deep sequencing-based on transcriptome analysis was deployed to understand leaf morphogenesis in Vitis vinifera. The KEGG pathway analysis revealed the transcripts involved in the biosynthesis of major metabolites leading to leaf growth. The highest number of DEGs were down-regulated at young leave-vs-mature leaves stages (3,501) followed by large leaves-vs-mature leaves (2,364); however, the minimum number of up-regulated transcripts were recorded at young leaves-vs-immature leaves (195). The gene regulation in the starch biosynthetic pathway, young leaves-vs-mature leaves showed the highest number of transcripts (24 up-regulated and 60 down-regulated). For ABC Transporters, 224 transcripts were expressed, among which the maximum number of transcripts (59) were recorded in large leaves-vs-mature leaves. Amino and nucleotide sugar metabolism showed 112 transcripts (22 up-regulated and 90 down-regulated), in which immature leaves-vs-mature leaves expressed 30 DEGs. In addition, Flavonoid pathway showed the highest number of transcripts i.e. 903 were expressed among the studied pathways. The findings of this study will also help to a better understanding of the underlying process during grape leaf morphogenesis and to unravel the mechanism. [ABSTRACT FROM AUTHOR]

Background: 3-Hydroxy-3-methylglutaryl-CoA reductase (HMGR) is a key enzyme in the mevalonate (MVA) pathway, which regulates the metabolism of terpenoids in the cytoplasm and determines the type and content of downstream terpenoid metabolites. Results: Results showed that grapevine HMGR family has three members, such as VvHMGR1, VvHMGR2, and VvHMGR3. The expression of VvHMGRs in 'Kyoho' has tissue specificity, for example, VvHMGR1 keeps a higher expression, VvHMGR2 is the lowest, and VvHMGR3 gradually decreases as the fruit development. VvHMGR3 is closely related to CsHMGR1 and GmHMGR9 and has collinearity with CsHMGR2 and GmHMGR4. By the prediction of interaction protein, it can interact with HMG-CoA synthase, MVA kinase, FPP/GGPP synthase, diphosphate mevalonate decarboxylase, and participates in the synthesis and metabolism of terpenoids. VvHMGR3 have similar trends in expression with some of the genes of carotenoid biosynthesis and MEP pathways. VvHMGR3 responds to various environmental and phytohormone stimuli, especially salt stress and ultraviolet (UV) treatment. The expression level of VvHMGRs is diverse in grapes of different colors and aroma. VvHMGRs are significantly higher in yellow varieties than that in red varieties, whereas rose-scented varieties showed significantly higher expression than that of strawberry aroma. The expression level is highest in yellow rose-scented varieties, and the lowest in red strawberry scent varieties, especially 'Summer Black' and 'Fujiminori'. Conclusion: This study confirms the important role of VvHMGR3 in the process of grape fruit coloring and aroma formation, and provided a new idea to explain the loss of grape aroma and poor coloring during production. There may be an additive effect between color and aroma in the HMGR expression aspect. [ABSTRACT FROM AUTHOR]

'Kyoho' grapevine (Vitis vinifera) treated by calcium ions solution has been proved as an effective treatment to extend grape quality during storage to reduce disease, but its molecular mechanism was not clear yet. In the current work, grape berries were treated with different concentration of Calcium chloride (CaCl2) solution, and their effects on antioxidant enzyme activity and transcriptome and metabolome in fruit were investigated. CaCl2 treatments reduced weight loss and inhibited the decrement of flesh firmness. 80 mM CaCl2 significantly increased the activity of antioxidant enzymes POD, SOD and CAT, which was the optimum experimental concentration. The study showed that the expression level of heat shock transcription factor and UBX which involved in endoplasmic reticulum stress and degradation pathway increased significantly. Moreover, the corresponding metabolites, such as heat shock protein and organic acid, also increased significantly. The misfolded proteins are transported to the cytosol for degradation, so that the preservation ability of grape is improved. [ABSTRACT FROM AUTHOR]

Summary: In grape, MYBA1 and MYBA2 at the colour locus are the major genetic determinants of grape skin colour, and the mutation of two functional genes (VvMYBA1 and VvMYBA2) from these loci leads to white skin colour. This study aimed to elucidate the regulation of grape berry coloration by isolating and characterizing VvMYBA2w and VvMYBA2r alleles. The overexpression of VvMYBA2r up‐regulated the expression of anthocyanin biosynthetic genes and resulted in higher anthocyanin accumulation in transgenic tobacco than wild‐type (WT) plants, especially in flowers. However, the ectopic expression of VvMYBA2w inactivated the expression of anthocyanin biosynthetic genes and could not cause obvious phenotypic modulation in transgenic tobacco. Unlike in VvMYBA2r, CA dinucleotide deletion shortened the C‐terminal transactivation region and disrupted the transcriptional activation activity of VvMYBA2w. The results indicated that VvMYBA2r positively regulated anthocyanin biosynthesis by forming the VvMYBA2r‐VvMYCA1‐VvWDR1 complex, and VvWDR1 enhanced anthocyanin accumulation by interacting with the VvMYBA2r‐VvMYCA1 complex; however, R44L substitution abolished the interaction of VvMYBA2w with VvMYCA1. Meanwhile, both R44L substitution and CA dinucleotide deletion seriously affected the efficacy of VvMYBA2w to regulate anthocyanin biosynthesis, and the two non‐synonymous mutations were additive in their effects. Investigation of the colour density and MYB haplotypes of 213 grape germplasms revealed that dark‐skinned varieties tended to contain HapC‐N and HapE2, whereas red‐skinned varieties contained high frequencies of HapB and HapC‐Rs. Regarding ploidy, the higher the number of functional alleles present in a variety, the darker was the skin colour. In summary, this study provides insight into the roles of VvMYBA2r and VvMYBA2w alleles and lays the foundation for the molecular breeding of grape varieties with different skin colour. [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]

Main conclusion: Transcriptome and physiological analysis showed that exogenous arginine can delay the ripening process of postharvest strawberry fruit. Arginine (Arg) plays an important role in the growth and development of plants, but its growth and development regulatory mechanisms in strawberry fruit are unknown. In this study, we found that the content of Arg decreased after the onset of fruit coloration and exogenous Arg inhibited fruit coloration. We comprehensively analyzed the transcriptome of ‘Sweet Charlie’ strawberry fruit with or without Arg treatment and identified a large number of differential genes and metabolites. Based on the transcriptome data, we also found that Arg inhibited ripening, which coincided with changes in several physiological parameters and their corresponding gene transcripts, including firmness, anthocyanin content, sugar content, Arg content, indole-acetic acid (IAA) content, abscisic acid (ABA) content, and ethylene emissions. We also found that Arg induced the expression of heat-shock proteins (HSPs) and antioxidant enzyme genes, which improved strawberry stress resistance. This study elucidated the molecular mechanism by which exogenous Arg delays strawberry fruit ripening, providing some genetic information to help guide the future improvement and cultivation of strawberry. [ABSTRACT FROM AUTHOR]

Chitinases (Chi), an important resistance-related protein, act against fungal pathogens by catalyzing the fungal cell wall, whereas are involved in different biological pathways in grape. In this study, we found 42 Chi family genes in Vitis vinifera L. (VvChis) and evaluated their expression levels after Botrytis infection, stress hormones like ethylene (ETH) and methyl-jasmonate (MeJA), and abiotic stresses like salinity and temperature changes in ripened fruits. VvChis were categorized into five groups including A, B, C, D, and E belonged to glycoside hydrolase family 18 and 19 (GH18 and GH19) according to genes structure, which expression analysis showed distinct temporal and spatial expression patterns changed in different tissues and various development stages. Different responsive elements to biotic and abiotic stresses were determined in the promoter regions of VvChis, specially elicitor-responsive element that was conserved among all VvChis genes. The expression levels of VvChis in groups A, B, and E increased after Botrytis cinerea infection in leaves and berries. Meanwhile, VvChis in glycoside hydrolase family 18 (GH18) were up-regulated under MeJA and ETH treatment, although the induction of VvChis by low temperature was more significant than high temperature. The expression of VvChis was also positively correlated with the concentration of NaCl treatment. Furthermore, differential gene-overexpression of VvChi5, VvChi17, VvChi22, VvChi26, and VvChi31 in strawberry and tomato fruits demonstrated the involvement of various isoforms in resistance to Botrytis infection through antioxidant system and lignin accumulation, which led to a reduction of damage. Among different isoforms of VvChis, we confirmed the interaction of Chi17 with Metallothionein (MTL) as oxidative stress protection, which suggests VvChis can modulate oxidative stress during postharvest storage in ripened fruits. [ABSTRACT FROM AUTHOR]

The fruit is the most important economical organ in the grape; accordingly, to investigate the grapevine genomic methylation landscape and examine its functional significance during fruit development, we generated whole genome DNA methylation maps for various developmental stages in the fruit of grapevine. In this study, thirteen DNA methylation-related genes and their expression profiles were identified and analyzed. The methylation levels for mC, mCG, mCHG, and mCHH contexts in 65 days after flowering (65DAF) fruit (véraison stage) were higher than those in 40DAF (green stage) and 90DAF (mature stage) fruits. Relative to methylation in the mC context, methylation levels in the mCHH context were higher than those of mCG and mCHG. The DNA methylation level in the ncRNA regions was significantly higher than that in exon, gene, intron, and mRNA regions. The differentially methylated regions (DMRs) and differentially methylated promoters (DMPs) in 65DAF_vs_40DAF were both higher than those in 90DAF_vs_65DAF and 90DAF_vs_40DAF. Most DMRs (or DMPs) were involved in metabolic processes and cell processes, binding, and catalytic activity. These results indicated that DNA methylation represses gene expression during grape fruit development, and it broadens our understanding of the landscape and function of DNA methylation in grapevine genomes. [ABSTRACT FROM AUTHOR]