| In this study,wine grape ‘Cabernet Sauvignon' was used as the experimental material.Two kinds of shading nets were used to shading the top of the vine at different growth stages of the grape berries for two consecutive years.High performance liquid chromatography-mass spectrometry(HPLC-MS)was used to detect co-pigment substances in grape berries and wine,tracked the effect of shading treatment on the color stability of wine during storage,and clarified the regulation mechanism of different light conditions on the biosynthesis of flavonoids in grape berries from the transcriptomics level.It is hoped that the content and composition of co-pigment substances in grape berries can be managed through appropriate shading treatment,and provided a theoretical basis for improving the color stability of wine during storage;the results showed:(1)The two black shading nets reduced the photosynthetically active radiation around the berries by20%,50%;when the grapes were harvested on the same harvest date after shading treatment,5% color transfer use of shading nets significantly(P<0.05)reduced the soluble solid content and the total amount of co-pigment substances in the grape berries,but increased the proportion of flavan-3-ols.The analysis of wine samples found that the wine body in the treatment group that used the shading net when the color was5% color transfer showed low alcohol content and low red hue;the four shading treatment groups all delayed yellowing degree in the wine storage process,the H1,H2 treatment group wine samples are better.(2)Analyzing the key points of consistent soluble solid content during the growth and development of grapes,it is found that shading treatment has no significant effect on total acid and p H.When the grapes reach maturity,shading treatments at different periods effectively prolong the phenology of grapes.In the5% color transfer,the shading treatment is delayed for 8 days,and the shading treatment when the color is100% changes,the berry is delayed for 13 days.According to the analysised of the accumulation of co-pigment substances in grape peel and the composition,it can be seen that 5% color transfer-fully mature,the use of shading net treatment with 50%(Q2)shading effectively increases the content of co-pigment substances in the peel.Significantly(P<0.05)increased the proportion of quercetin in the peel.(3)The wine body was analyzed,and the alcohol content of the wine samples of the four treatment groups was lower than that of the control wine samples.After the grape berry was processed with the shading net 2(50%),the wine samples showed high brightness and low red color expression;at the same time;After grape berries are treated with shading net 1(20%),the yellowing speed of wine samples slows down.(4)Combined with the results of the transcriptome,it was proved that the use of shading net treatment at different stages of berry development increased the expression of genes related to the synthesis of auxiliary color substances,such as the expression of Vv FLS,Vv LAR,and Vv ANR,as well as the expression of F3'H.The expression of flow-oriented substances,such as quercetin;and further proved the expression changes of the specific regulatory factors Vv MYBPA1 and Vv MYBF1 in the grape co-color substance synthesis pathway after shading treatment and the expression of Vv FLS,Vv LAR1,Vv LAR2 genes and flavans,the accumulation of alcohols and flavonols is positively correlated. |
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