Involvement Of Abscisic Acid And 24-Epibrassinolide On The Regulation Of Ripening And Proanthocyanins Biosynthesis Of Grape Berries

The experiment was conducted from June to october in 2012 vintage,and Vitis vinifera L.cv.Cabernet-Sauvignon grapes were used in this study from a commercial vineyard in the Xiangning County,Shanxi Province(China).There were four treatments in this study:1)100 mg·L-1 ABA(sprayed at 10 days after anthesis,"ABA");2)0.4 mg·L-1 EBR(sprayed at 10 days after anthesis,"EBR(once)");3)0.4 mg·L-1 EBR(sprayed at 10 days after anthesis)+0.4 mg·L-1 EBR(sprayed at 14 days before veraison)("EBR(twice)");4)water treatment as control(sprayed at 10 days after anthesis,"CK").During grape development and ripening,physicochemical indexes(cluster weight,100 berry-weight,reducing sugar,total acid),phenolic compounds(total phenolics,proanthocyanidins,flavanol,anthocuanidin),expression levels of proanthocyanidin biosynthetic related genes,anthocyanidins and non-anthocyanidin phenolic substances and the quality of corresponding wines were determined to study the effects of exogenous ABA and EBR on grape ripening and proanthocyanidin biosynthesis.The main results demonstrated as follows:1.Application of exogenous ABA and EBR promoted berry ripening by enhancing the content of cluster weight,100 berry-weight,reducing sugar,and decreasing total acid content compared with control during fruit development and ripening.The cluster weight of exogenous ABA and EBR treatment were significantly higher than control,ABA treatment increased 29%than control,then was EBR(twice)and EBR(once),increased 18%and 10%than control,respectively.EBR(twice)treatment increased 100 berry-weight,and had significant difference with control at mature period,but the difference of ABA and EBR(once)with control were not significantly.The content of reducing sugar of exogenous ABA and EBR treatment were significantly higher than control.On the contrary,total acid content in treated grapes were lower than control,EBR(twice)and EBR(once)treatment decreased more significantly than ABA,and had significant difference with control at mature period,but the difference of ABA with control was not significantly.2.Application of exogenous ABA and EBR enhanced proanthocyanidins,total flavanol,total phenolics,total anthocyanidin accumulation,resulting in significantly higher content than control during fruit development and ripening.The total phenolics content of exogenous ABA and EBR treatment were significantly higher than control,EBR(twice)treatment increased 34%,then was EBR(once)and ABA,increased 31%and 24%than control,respectively.The proanthocyanisins of exogenous ABA and EBR treatment were higher than control,EBR(twice)and EBR(once)treatment increased 109%and 92%,respectively,and had significant difference with control at mature period,then was ABA,increased 24%than control.The total flavanol of exogenous ABA and EBR treatment were significantly higher than control,EBR(twice)treatment increased 101%,then was EBR(once),increased 62%than control.The anthocyanidin content of exogenous ABA and EBR treatment were significantly higher than control,EBR(twice)treatment increased 30%,and ABA had smallest increase range at 5%。3.The pH value,alcohol,total extact,dry extact content in corresponding wines of ABA and EBR treatment were higher than control,and total acid was lower than control.The proanthocyanidins,total flavanol,total phenolics,total anthocyanidin content were higher than control.The total phenolics and total flavanol content of exogenous ABA and EBR treatment were significantly higher than control,the increase range were EBR(twice)>ABA>EBR(once)and ABA>EBR(once)>EBR(twice).The proanthocyanisins and anthocyanisin content of exogenous ABA and EBR treatment increase range were EBR(twice)>ABA>EBR(once).The proanthocyanisins content of EBR(twice)increased 35%than control,and had significant difference with control at mature period,but the difference of EBR(once)and ABA with control were not significantly.The anthocyanisin content of EBR(once)and EBR(twice)treatment increased higher than ABA,and had significant difference with control at mature period,but the difference of ABA treatment with control were not significantly.4.Exogenous ABA and EBR treatment could control mRNA levels of proanthocyanidin biosynthetic related genes VvLARl,VvLAR2,VvANR,VvANS,VvMYB5a,VvMYB5b and VvMYBPA1 during grape skin development to regulating the proanthocyanidin biosynthesis.The expression levels of VvLAR1,VvLAR2 and VvANR increased dramatically until reached the highest point at young fruit stage,then declined up to harvest.At young fruit stage,ABA and EBR treatment lower than control of VvLAR1 expression level,but higher than control of VvLAR2 and VvANR expression level.VvANS expression level fixed in time and kept low level from fruit setting stage to veraison,then raised sharply to harvest.ABA and EBR treatment promoted this gene expression,especially EBR(twice).VvMYB5a expression level peaked at young fruit stage and veraison,but VvMYBPA reached the highest point at young fruit stage,then declined dramatically up to harvest.ABA and EBR treatment increased VvMYB5a and VvMYBPA gene expression level.5.Nine kinds of anthocyanidin were determined in grape skins and corresponding wines,concluding 5 kinds of basic anthocyanidin and 4 kinds of acidylated anthocyanisin.Exogenous ABA and EBR treatment could control the composition and content of anthocyanidin in grape skins,resulting in higher anthocyanidin content than control,the increase range were EBR(twice)>EBR(once)>ABA.The anthocyanidin content in wines of exogenous ABA and EBR treatment were higher than control,the increase range were EBR(twice)>EBR(once)>ABA.The anthocyanidin content of EBR(twice)treatment was higher than EBR(once).6.Eighteen kinds of non-anthocyanidin phenolic substances were determined in grape skins.Exogenous ABA and EBR treatment could promote the non-anthocyanidin phenolic substances accumulation,the increase range were EBR(twice)>EBR(once)>ABA.ABA and EBR treatment declined the catechin and epicatechin level in grape skins,except the catechin content of EBR(once)treatment.The non-anthocyanidin phenolic substances content in corresponding wines of exogenous ABA and EBR treatment were higher than control,the increase range were EBR(twice)>ABA>EBR(once).However,the composition and content of non-anthocyanidin phenolic substances of ABA and EBR treatment were different with control,17 kinds in ABA and in EBR(once),16 kinds in EBR(twice),15 kinds in control were detected,respectively.