Effect Of Water Stress On Volatile Compounds And Expression Of Related Genes Fruiting Branches In Muscat Hamburg Grape

In order to explore the effects of water stress on volatile flavor and related gene expression in Muscat Hamburg grape,The 10-year-old 'Muscat Hamburg' grape was used as experimental material.Grape plants were treated with moderate stress(T1,-0.4 MPa??b?-0.6 MPa)and severe stress(T2,-0.6 MPa??b)from veraison to harvest,and no water stress was used as control(CK),.The 100-grain weight,soluble solids,volatile flavor compounds and volatile compounds related genes of grape fruits treated with different treatments were determined.The results were as follows:1.Different water stress had a great effect on the fruit quality of 'Muscat Hamburg' grape.At harvest time,water stress decreased the 100-grain weight of the fruit,and compared with CK,T1 and T2 decreased by 1.05%and 20.23%respectively;T1 increased the fruit type index;T1 and T2 reduced the titratable acid content of fruit;The total phenol content of T2 increased by 11.05%compared with CK;Water stress reduced the amino acid content of fruit,and compared with CK,T1 and T2 decreased by 11.92%and 23.98%respectively.The results showed that T1 was beneficial to the improvement of fruit quality.2.The effects of different water stress on the types and total concentration of volatile compounds during grape fruit ripening were different.It was found that 41 kinds of volatile compounds were detected by CK in mature stage,and the total concentration of volatile compounds was 1213.11?gg/L;The T1 had detected 43 kinds of volatile compounds,and the total concentration was 1634.6 ?g/L;The T2 had 33 kinds of volatile compounds,and the total concentration was 1193.85?g/L.3.In the process of grape fruit volatile compound accumulation,the concentration of aldehydes accounted for the highest proportion.The effects of different water stress on the concentration of aldehydes in grape fruits at different growth stages were different.The highest relative content of aldehydes was 2-hexenal with green leaf and fruit aroma.Compared with CK,the relative content of 2-hexenal in T1 increased by 43.14%and decreased by 48.52%in T2.4.Different water stress had on the different effects on the content of terpenes in grape fruits,but did not change their accumulation patternsn.In the mature stage,the highest content of terpenes was linalool with rose flavor,followed by ?-terpenol.The linalool content of grape fruits treated with T1 and T2 was 29.33%and 45.08%higher than that of CK,respectively.5.In the process of fruit growth and development,damasone and 2-pyrrolidone can be detected in all treatments,and damasone has the scent of rose flowers.Compared with CK,the content of damadone in grape fruits treated with T1 and T2 at harvest time decreased by 17.99%and 57.81%,respectively,indicating that water stress was not conducive to the accumulation of Damadone.6.The effects of water stress on the expression of genes related to volatile compound synthesis during grape fruit development were different..Compared with CK,T1 promoted the expression of VvGPPS and VvTPS during fruit development,while T1 and T2 down-regulated VvLIS and VvCCD1 genes.Correlation analysis showed that the expression of VvGPPS was strongly correlated with terpenes,while the expression of VvLIS,VvTPS and VvCCDl was weakly correlated with terpenes.To sum up,T1 could improve the accumulation of volatile compounds by upregulated volatile compounds synthesis genes,thus improving fruit quality.