Effects Of Exogenous Salicylic Acid Treatment On Organic Acid Accumulation In ’Beihong’ And ’Cabernet Sauvignon’ Grapes Under Water Stress

In order to determine the effects of water stress and exogenous salicylic acid treatments on the accumulation of organic acids and salicylic acid in ’Beihong’ and ’Cabernet Sauvignon’ grape berries,this experiment was carried out on red wine grape varieties Vitis vinifera×Vitis amurensis L.Beihong and Vitis vinifera L.Cabernet Sauvignon.The effects of different soil water stresses and pre-harvest foliar sprays of salicylic acid on grape berry quality,organic acid and salicylic acid contents in the berry and the expression of genes related to their anabolism were studied during the annual growth period.The results were as follows:(1)Soil water content and foliar spraying of salicylic acid both affected fruit quality.Drought stress treatments significantly reduced the 100-grain weight and titratable acid content of ripening grapes and promoted the accumulation of soluble solids and anthocyanins.Under drought stress,300 mg/L exogenous salicylic acid treatment significantly promoted the accumulation of soluble solids and anthocyanins.(2)Soil water content and foliar spraying of salicylic acid both affected the organic acid content of grape berries.Under drought stress,the organic acid content was higher than the control in the early stage of fruit development and significantly lower than the control in the ripening stage.Under drought stress,exogenous salicylic acid treatment mainly affected malic acid content,in which 500 mg/L exogenous salicylic acid treatment significantly promoted malic acid accumulation in grape berries.(3)Soil water content and foliar spraying of salicylic acid both affected organic acid synthesis and metabolism genes of grape berries.Under drought stress,the relative expression of organic acid synthesis and transporter genes was lower than that of the control at the ripening stage.Under drought stress,the relative expression of organic acid synthesis and transporter genes was significantly increased by 500 mg/L exogenous salicylic acid treatment with increasing treatment time.(4)Soil water content and foliar spraying of salicylic acid both affected salicylic acid accumulation in leaves and grape berries.Salicylic acid accumulation was tissue-specific,and endogenous salicylic acid content in leaves and grape berries was negatively correlated;drought stress treatment significantly promoted endogenous salicylic acid accumulation in grape berries during color change and ripening.Under drought stress,300 mg/L exogenous salicylic acid treatment significantly increased the endogenous salicylic acid content in grape berries.(5)Soil water content and foliar spraying of salicylic acid both affected salicylic acid synthesis and metabolism genes of leaves and grape berries.Drought stress treatment induced the expression of leaf salicylic acid synthesis genes and signal transduction genes VvNPR4 and VvWRKY18,while the relative expression of VvNPR1 gene was also significantly higher in grape berries than the control.Under drought stress,with increasing treatment time,100 mg/L and 300 mg/L exogenous salicylic acid treatments significantly increased the relative expression of VvICS and VvPAL genes in leaves and significantly suppressed the relative expression of VvNPR1 and VvWRKY18 in grape berries,respectively.