Relationship Between Seed Content And Berry Ripening Of Wine Grape (Vitis Vinifera L.)

The experiment was conducted for two years in Changyu Rui Na Chateau,Xianyang,Shaanxi.In 2016,Cabernet Sauvignon(Vitis vinifera L.)and Cabernet Gernischt(Vitis vinifera L.)were used as test materials,of which Cabernet Gernischt was treated with50mg/L IAA.Grape berries and their seeds were weighed one by one,after which the grapes were divided into Low-SB and High-SB grapes based on the ratio of seed weight to berry weight(SB).The differences between Low-SB,High-SB grapes in the total phenols of skin,anthocyanin,tannin of seeds,abscisic acid(ABA)and auxin(IAA)content of berry were comparisoned,as well as combining IAA treatment,to investigate the effect of IAA treatment and seed weight to berry weight on grape berry ripening.The results obtained are as follows:(1)At veraison,the sugar and anthocyanin of Low-SB grapes began to accumulate,as well as declining the total phenols in skin and tannin in seeds.However,there was no significant change of sugar,anthocyanin and tannin in High-SB grapes,accompanied by the further increase of the total phenol in skin,indicating that Low-SB grapes entered ripening onset earlier than High-SB grapes.Low-SB grapes contained higher sugar and anthocyanin,meaning that they ripened faster than High-SB grapes.However the differences between the two SB groups in sugar and phenol conthent gradually reduced,showing that the difference in grape ripening gradually decreased.At harvest time,Low-SB grapes had higher anthocyanin and total phneol,which benifited to wine quality.(2)There was a higher ABA and lower IAA content in Low-SB grapes than that of High-SB grapes during ripening so that Low-SB grapes ripened faster than High-SB grapes.But there was no significant difference or a little difference in ABA and IAA content between Low-SB and High-SB grapes in the late ripening stages,indicating that the regulation effect of ABA and IAA on sugar acumulation was no longer obvious at harvest time.(3)The sugar content,anthocyanin content,color conversion rate of IAA treated grapes were lower than that of CK while SB value,tannin in seed was higher,showing that IAA treatment delayed grape ripening.When mixed the same amount of grapes from CK and IAA-treated groups,the grapes were splited into Low-SB and High-SB grapes according to their seed weight to berry weight,the result of which was that IAA treatment contained more High-SB grapes,while CK contained more Low-SB grapes,further confirming that Low-SB grape ripened faster than High-SB grapes.In addition,the sugar accumulation of IAA treatment was more synchronous than that of the CK.(5)Low-SB grapes reduced the expression of VvBG1,VvNCED1,Vv GH3-1 and up-regulated the expression of Vv YUC1 to decrease and increase the content of ABA and IAA,respectively,so that they ripened fater than High-SB grapes.IAA treatment reduced the expression of VvBG1,VvNCED1 to decrease the ABA conten,which delayed berry ripening.Containing higher IAA content,the IAA treatment increased the relative expression level of Vv GH3-1 while decreased Vv YUC1 expression,the effect of which may be to alleviate the inhibition of grape ripening by IAA treatment.IAA treatment had higher IAA content than that in CK,which may be through regulating the expression of other genes related to auxin synthesis,or it may be due to IAA in IAA treatment solution being directly absorbed by grape berry,thereby increasing the content of IAA in fruits.In summary,Low-SB grapes ripened faster than High-SB grapes,but the difference gradually reduced;IAA treatment delayed berry ripening,but improved the synchronization of sugar accumulation.