Study On The Regulation Of Anthocyanin Synthesis Of Grape And The Quality Of Wine After Brassinolide And Abscisic Acid Treatments

Color is the first sensory characteration of wine, which is related to anthocyaninscomponents in wine. It is generally known that anthocyanins in wine mainly derived fromgrape berries. However, for some wine-producing regions, it is impossible to make premiumwines due to their adverse environmental stresses. Brassinosteroids (BRs) are the latest planthormones controlling berry ripening and anthocyanins accumulation, which has been focusedon by many researchers. However, the mechanism of brassinosteroids regulating anthocyaninbiosynthesis was still not clear. Abscisic acid (ABA) was accepted generally as the planthormones promoting grape ripening and coloration, but its effect on the anthocyaninscomposition in grape and wine was also not reported. In this study, Vitis vinifera L. cv.Cabernet Sauvignon and Yan73were used as materials to study anthocyanins accumulationand change, anthocyanins components of grape skin and wine, expression of anthocyaninsbiosynthesis genes and BR biosynthesis and receptor genes of grape skin, as well asendogenous ethylene release and ABA content change through spraying24-Epibrassinolide(EBR) and ABA solution on grape berries at prevarasion by using real-time quantitative PCR,gas chromatograph, HPLC and HPLC-MS technology. The study aims to provide theoreticalbasis on the mechanism of brassinosteroids regulating anthocyanin biosynthesis, as well asprovide theoretical support to the future exploration of premium wines in the inferiorwine-producing regions. The main research contents and results as below:(1) Basic chemical indexes of grape and wine after ABA and EBR treatments weredetermined.ABA and EBR treatments increased the sugar content in the berry and the anthocyaninaccumulation in the berry skin significantly, enhanced the content of tannin and total phenolsin the wine, as well as reduced the total acidity of berry and wine.(2) The impacts of ABA and EBR treatments on anthocyanins composition in the berryskin were investigated.ABA and EBR treatments increased the total content of monomer anthocyanins inCabernet Sauvignon and Yan73grape skins significantly, advancement range of B-ring-3’-substituted anthocyanins was greater than that of3’5’-substituted anthocyanins, andthe ratio of B-ring-methoxylated anthocyanins was reduced. In addition, the ratio ofnon-acylated anthocyanins was reduced and the ratio of acetylated anthocyanins wasenhanced in Cabernet Sauvignon and Yan73grape skins by EBR treatment. While, the effectsof ABA on the non-acylated and acylated anthocyanins in Cabernet Sauvignon and Yan73grape skins were different.(3) Anthocyanins composition of the wines from the ABA-treated and EBR-treatedberries was analysized.For Cabernet Sauvignon and Yan73wines, the total content of individual anthocyaninswas enhanced significantly, and the ratio of B-ring-methoxylated anthocyanins was reduced,as well as the content of non-acylated anthocyanins were mainly enhanced under ABA andEBR treatments. In addition, the ratio of B-ring-3’-substituted anthocyanins was reduced byEBR treatment and that was enhanced by ABA treatment in Cabernet Sauvignon and Yan73wines.(4) Gene expression change of anthocyanin biosynthesis in the Cabernet Sauvignon andYan73skins after EBR and ABA treatments was evaluated.For Yan73grape, the expressions of genes for anthocyanin biosynthesis in Yan73skinwere improved, but the expression peaks were not in advance under ABA and EBR treatments;For Cabernet Sauvignon grape, the expressions of genes for anthocyanin biosynthesis wereimproved and the expression peaks were induced in advance under ABA and EBR treatments.Also, the effect of ABA and EBR treatments on the downstream genes was more pronouncedthan on the upstream genes, and the genes that limited the advancement ranges of fullcoloration were different in the ABA-treated grapes and EBR-treated grapes, which was theexpression of upstream genes CHI or CHS in the EBR-treated grapes, and was the expressionof upstream genes CHI mainly in the ABA-treated grapes.(5) Gene expression change of biosynthesis and receptor genes of brassinosteroid afterEBR and ABA treatments was estimated.The expressions of biosynthesis genes (DWF1and BR6OX1) and receptor gene (BRI1) ofbrassinosteroid were improved by ABA and EBR treatments. The effects of ABA and EBRtreatments on the genes expressions of BR6OX1and BRI1were similar with on thedownstream genes expressions for anthocyanin biosynthesis. Then, the biosynthesis geneBR6OX1and receptor gene BRI1might have relationship with the biosynthesis ofanthocyanin.(6) Ethylene evolution and ABA content of the grape berries after EBR and ABA treatments were estimated.The content of ethylene release was enhanced significantly in Cabernet Sauvignon andYan73grapes under exogenous ABA and EBR treatments, and the accumulation ofanthocyanin fell behind the release of endogenous ethylene. Also, the content of endogenousabscisic acid was enhanced in Cabernet Sauvignon and Yan73grapes under exogenous ABAand EBR treatments, and that has relationship with the release of endogenous ethylene as wellas the anthocyanin accumulation. Then, the enhancement of ethylene release and endogenousabscisic acid content might be part of the reasons which caused the improvement ofanthocyanin accumulation under exogenous ABA and EBR treatments.