Studies On The Regulation Of Ripening And Anthocyanin Biosynthesis Of Grape Berries By Brassinosteroid And Aba

The experiment was conducted with wine grape Cabernet Sauvignon and Yan73fromMay to September2011in Qijiazhai wine grape base, Jingyang County, Xianyang City,Shaanxi Province, Baiwang town. Different concentrations of exogenous2,4-epibrassinolide(EBR,0.1,0.4,0.8mg·L^-1), brassinazole (Brz,1mg·L^-1, an inhibitor of BR biosynthesis) andabscisic acid(ABA,200mg·L^-1)were respectively applied evenly to the berries one to twoweeks (two weeks of Cabernet Sauvignon, one week of Yan73) before veraison. In theprocess of grape ripening, the changes of berries colored and the weight of grape berries wererecorded; the soluble solids content and ACC oxidize (ACO) activity in grape berries and theenzyme activities of phenylalanine ammonia-lyase (PAL), UDP-glucose:flavonoid-3-O-glycosyltransferase (UFGT) and alcohol dehydrogenase (ADH) in grape skin were analyzed;the rate of ethylene release was analyzed using gas chromatograph (GC) and the content ofgrape berry endogenous ABA, IAA and GA3was determined using high performance liquidchromatogram(HPLC). In order to explore the regulation mechanism of ripening andanthocyanin biosynthesis of grape berries by brassinosteroid and the interaction betweenexogenous hormones in the process of grape ripening, the research on the effects ofexogenous EBR and ABA on the grape coloring, the content of soluble solids, the enzymeactivities of PAL, UFGT and ADH in gape skins, the release of ethylene and the enzymeactivities of ACO and the content of endogenous ABA, IAA and GA3was conducted. Themain results of this experiment demonstrated as follows:1. At the beginning of the fruit coloring, the enzyme activities of PAL, UFGT and ADHin berry skins increased. The activities of PAL of Cabernet Sauvignon were on the rise in theprocess of grape ripening. The activities of PAL, UFGT and ADH in the skins of CabernetSauvignon and PAL activities of Yan73decreased after the grape berries approachingmaturity and the anthocyanin accumulation becoming basically stable.2. In the early stage of grape coloring, the content of berry endogenous IAA and GA3decreased. The IAA content increased slightly in the process of fruit ripening, while thecontent of GA3was basically stable. After veraison, the ethylene release rate increased sharply, and the ABA content in grape berry started to accumulate. The ethylene release rate sharplydecreased, whereas the content of berry endogenous ABA content increased rapidly when thefruit anthocyanins began a large number of syntheses. After the fruit approaching maturityand the anthocyanin accumulation becoming basically stable, the ABA content started todecrease. The changes of grape berry ACO activity were basically parallel to ethylene releaserate.3. Compared with the control, the coloring and fruit ripening of Cabernet Sauvignon andYan73were promoted by exogenous EBR and ABA treatments. In the early stage of grapecoloring, the IAA content of grape berries treated with0.4mg·L^-1EBR and200mg·L^-1ABAwas lower than that of the control. As grape ripening, the difference of fruit IAA contentbetween EBR and ABA treated berries and control decreased gradually. No significantdifference of IAA content was found between0.1mg·L^-1and0.8mg·L^-1EBR treated berriesand the control. In the process of grape berry ripening, treatments with0.4mg L^-1EBR and200mg L^-1ABA increased the berry ACO activity and promoted the ethylene releasing,meanwhile increased the content of endogenous ABA and the enzyme activities of PAL,UFGT and ADH in grape skins, and promoted grape coloring and acceleration of the solublesolids of grape berries. In different concentrations of EBR treatments,0.4mg L^-1EBR hadbetter effects. Berries treated with ABA and varied concentrations of EBR had no significantdifference in GA3content with that of control.4．Compared with the control, treatment with1mg·L^-1Brz increased the berry IAAcontent and decreased the ACO activity and ethylene release rate of grape berries, and thebiosynthesis of ABA in grape berries and fruit coloration was delayed. The berry solublesolids content and the enzyme activities of PAL, UFGT and ADH in beery skins were lowerthan that of control. After Brz treatment, the grape berry endogenous GA3content had nosignificant differences with that of control.5. In the early stage of grape ripening, the grape berry endogenous IAA contentdecreased, and the ethylene release rate increased rapidly. After treated with EBR and ABA,the biosynthesis of IAA in grape berries was inhabited, the rate of fruit ethylene release wasincreased, and the accumulation of anthocyanin and soluble solids content of grapes waspromoted. In the process of grape maturation, the changes of fruit endogenous ABA contentwere parallel to the fruit ripening process. Exogenous EBR and ABA treatments increasedfruit endogenous ABA content, and promoted biosynthesis of anthocyanin and accumulationof soluble solids in berries. The content of GA3in grape berries changed little in the processof grape ripening, and the GA3content of grape berries treated with EBR and ABA had nosignificant difference with that of the control. Berry coloring and fruit ripening as induced by EBR and ABA was likely associated with decrease in berry endogenous IAA content andincrease in ethylene and ABA content, but maybe not with the changes of berry GA₃contentin the process of Cabernet Sauvignon and Yan73maturation.