Effects Of Exogenous SA On Fruit Quality And Endogenous SA Accumulation Of ’Beihong’ And ’Cabernet Sauvignon’

Eight-year-old wine grape varieties ’Beihong’ and ’Cabernet Sauvignon’ were selected as experimental materials in this experiment.SA was sprayed on grapes from late July to early August,to study its effects on grape fruit quality and antioxidant enzyme activity,endogenous salicylic acid and its metabolic and signaling pathway related gene expression were detected,to explore the role of SA in regulating fruit quality during fruit development,to explore the role of SA in regulating fruit quality during fruit development and provide reference for improving wine grape quality.The results are as follows:1.Effects of exogenous SA treatment on the quality of ’Beihong’ and ’Cabernet Sauvignon’ grapes.There was no significant difference in 100-grain weight between ’Beihong’ and ’Cabernet Sauvignon’during the whole growth cycle,especially ’Cabernet Sauvignon’.After the grape entered the color turning stage,the carbohydrate in grape fruits under all SA treatments increased gradually,and the organic acid content gradually decreased.At the harvest stage,the carbohydrate content reached the highest value,and the organic acid content reached the minimum value,and the change trend of each treatment remained unchanged.At the harvest stage(110 d after anthesis),5 mmol/L SA treatment group could significantly reduce the titratable acid content in grapes,the soluble solid content of’Beihong’ grape sprayed with 5 mmol/L SA was significantly lower than that of the control group.The other two treatments were beneficial to the accumulation of soluble solid,while the difference of soluble solid content between ’Cabernet Sauvignon’ SA treatment group and the control group was not significant,3 mmol/L SA treatment can effectively increase the content of carbohydrate and phenolic substances in grape fruits.The SA treatment group was beneficial to the improvement of fruit quality of grapes.2.Effects of exogenous SA treatment on endogenous salicylic acid content of‘Beihong’ and’Cabernet Sauvignon’ grapes.The content of SA in grape leaves was significantly higher than that in fruit.5 mmol/L salicylic acid treatment significantly increased the content of SA in ’Beihong’ and’Cabernet Sauvignon’ fruits,and was beneficial to the accumulation of free and bound SA in’Beihong’ and ’Cabernet Sauvignon’ leaves.1 mmol/L SA and 5 mmol/L SA significantly increased the content of free salicylic acid in ’Cabernet Sauvignon’ grapes.The correlation analysis between fruit variety indexes and endogenous salicylic acid at harvest stage showed that 3 mmol/L SA treatment group was positively correlated with tannin,reducing sugar and total sugar of ’Beihong’ and ’Cabernet Sauvignon’ grapes.5 mmol/L SA treatment group was positively correlated with the content of bound SA,free SA and free SA in ’Beihong’ grape fruit,1 mmol/L SA treatment group was positively correlated with the content of titratable acid in ’Beihong’ fruit,but negatively correlated with the content of total anthocyanins and the content of bound SA in leaves.There was a positive correlation between 1 mmol/L SA treatment group and total phenols,free and conjugated SA in ’Cabernet Sauvignon’ fruit,and 5 mmol/L SA treatment group and free and conjugated SA in ’Cabernet Sauvignon’ grape leaves.3.Effects of exogenous SA treatment on antioxidant properties of ’Beihong’ and ’Cabernet Sauvignon’ grapes.3 mmol/L SA treatment group significantly increased POD enzyme activity in leaves of ’Beihong’ and ’Cabernet Sauvignon’,1 mmol/L SA treatment group was more conducive to improving SOD activity expression in leaves of ’Beihong’,3 mmol/L SA treatment group had the best effect on improving SOD activity in leaves of ’Cabernet Sauvignon’.The POD enzyme activity in leaves of 5 mmol/L SA treatment group was lower than that of control group in the five stages of’Beihong’ growth and development,and the activity of antioxidant enzymes in grape leaves was decreased by high concentration SA treatment.4.Effects of exogenous SA treatment on expression levels of genes related to endogenous salicylic acid synthesis pathway in ’Beihong’ and ’Cabernet Sauvignon’ grapes.1 mmol/L SA increased the VvNPR1 gene expression in ’Cabernet Sauvignon’ leaves and ’Beihong’ fruit,and 3 mmol/L SA significantly increased the VvNPR1 gene expression in ’Cabernet Sauvignon’ fruit and leaves.However,the expression of VvNPRl gene and VvWRKY50 gene in Beihong’ fruits and leaves was inhibited.5 mmol/L SA increased the relative expression levels of VvPAL and VvAIM1 genes in ’Beihong’ fruits and leaves,and the expression levels of VvPBS3 and VvWRKY50 genes in grapes during harvest period.