Effects of rootstocks on the content of resveratrol and relative enzyme activities in ‘Cabernet Sauvignon' grape

Abstract: 【Objective】Xinjiang is the largest wine production region in western China. Cabernet Sauvignon (CS) , as a wine-making variety, has continued to expand in Xinjiang. However, due to the adverse ecological environment in Xinjiang, it often suffers from salinity, drought, high and low temperatures and other adverse factors that reduce the quality of the berry. Resveratrol (Res) is a kind of non-flavonoid polyphenol compound with astragalus structure, which has been found in 72 species including grape, giant knotweed, peanut, mulberry and so on. It has physiological functions such as anti-oxidation, cardiovascular protection, anti-cancer and anti-aging. This study analyzed the changes in resveratrol and related enzyme activities in Cabernet Sauvignon grape grafted on different rootstocks during berry development and their relationships in order to select scion-rootstock combinations with high resveratrol content for northern Xinjiang.【Methods】Five resistant rootstocks (3309 C, 1103 P, 140 R, SO4 and 5 C) were all from Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences.The scion was Cabernet Sauvignon 169 (CS) . The rootstock-scion combinations included CS/3309 C, CS/1103 P, CS/140 R, CS/SO4 and CS/5 C. The self-rooted Cabernet Sauvignon plants were regarded as the control. The experimental rootstock combinations were planted in the experimental field by hardwood grafting in 2015, and samples were taken at four stages at interval of 15 days (8-10, 8-25, 9-10, 9-25) from color-break stage (August 10) until the fruit was fully ripe (September 25) in 2018. Five clusters of fruit were randomly selected for each treatment, and the skin and seeds were accurately separated after mixing evenly. 0.3 g of each sample was weighed and repeated 5 times. The samples were stored in a freezer at-80 C after quick freezing with liquid nitrogen. The Res content and the activities of phenylalanine ammonia lyase (PAL) , cinnamic acid 4-hydroxylase (C4 H) , 4-coumarate CoA ligase (4 CL) , Malonly-CoA (COA) and 4-coumaroyl-CoA (4 CA) in skins and seeds of Cabernet Sauvignon grapes were determined. The Res content and the activities of PAL, C4 H, 4 CL, COA and 4 CA in the skins and seeds were analyzed. The pattern of change was observed in each period, and the correlations between Res content and related enzyme activities were analyzed.【Results】The results of this study indicated that the rootstock had an effect on the Res content and its related enzyme activities. The contents of Res in CS/140 R, CS/SO4 and CS/5 C skins and seed were higher compared with CK. Among them, the CS/140 R combination had the highest Res content, while the CS/1103 P and CS/3309 C combinations had no significant difference compared with CK. Rootstocks could significantly increase the activities of Res synthesis-related enzymes. Compared with CK, 140 R significantly increased the activities of all the enzymes, which were significantly higher than the other rootstock combinations. Compared with the control, SO4 significantly increased the activities of PAL, 4 CA and COA in the skins and seeds; 3309 C significantly increased the activities of PAL and 4 CL in seeds; 1103 P significantly increased the activities of PAL, C4 H and PAL in the skin. The activities of PAL, C4 H and 4 CL in the seeds and skins of 5 C rootstock were lower, and only 4 CA and COA activities were higher, but the content of Res in the skins was higher, which may be related to the influence of 4 CA and COA on Res synthesis. The correlation analysis between the activities of PAL, C4 H, 4 CL, COA and 4 CA and Res content showed that there was a significant correlation between the activities of these five enzymes and Res content in seeds and skins, and the correlation coefficients between the activities of COA and 4 CA and Res content were the largest.【Conclusion】It is concluded that compared with self-rooted seedlings, the resistant rootstocks could increase Res contents in CS grape seeds and skins and the activities of key enzymes involved in its synthesis. The combination of CS/140 R significantly improved the Res content and COA and 4 CA activities in the seeds and skins of Cabernet Sauvignon grape.