Effects Of Water Stress On Resveratrol Accumulation And Synthesis In Berries Of Cabernet Sauvignon

Resveratrol,as a phytoalexin,plays a key role in the plant resistance to environment stresses.Meanwhile,resveratrol also has a variety of biological activities beneficial to human body.Biotic and abiotic stresses can induce resveratrol accumulation in grapevine.There are few studies on the effects of water stress on resveratrol accumulation and synthesis in grape berries.In addition,with the aggravation of global warming and water shortage,water stress or drought may become the main environmental factors limiting the development of some wine regions.Therefore,the 15-year-old wine grape Cabernet Sauvignon from Huangyangtan vineyard in Ningxia was used as the research material.Water stress was carried out from setting to ripening.The predawn leaf water potential value was used to reflect the degree of water stress.We will set up control group,treatment group 1 and treatment group 2,respectively.Their predawn leaf water potential value is-0.20 Mpa ≥ φpredawn ≥-0.40 Mpa,-0.40 Mpa ≥φpredawn≥-0.60 Mpa and-0.60 ≥φpredawn,respectively.We mainly studied the changes of resveratrol and some of its derivatives in the process of grape berries growth and the effects of water stress on the biosynthesis of resveratrol in grape berries.The main results are as follows:(1)Effects of water stress on berries characteristics and composition during berries growth and development of grapevine.Water stress makes veraison earlier.Berries weight,volume and titratable acid content of maturity berries were significantly reduced,but soluble solids,total phenols and anthocyanins content of maturity berries were increased in T1 and T2.The content of resveratrol and some of its derivatives increased with berries ripening.The contents of cis-resveratrol and trans,resveratrol were increased in both T1 and T2 groups.The increases of cis-resveratrol were 0.36 mg g-1 and 1.30 mg g-1,respectively.The increases of rans-resveratrol was 0.91 mg g-1 and 3.10 mg g-1,respectively.Both T1 and T2 groups reduced the contents of cis-and trans-piceid.The reduction of cis-piceid was 2.27 mg g-1,3.80 mg g-1,and that of trans-piceid was 0.63 mg g-1 and 0.38 mg g-1,respectively.(2)Effects of water stress on endogenous hormones abscisic acid,jasmonic acid and salicylic acid in grape berries growth and development.With the ripening of grape berries,the contents of salicylic acid and abscisic acid in grape berries increased gradually,while the contents of jasmonic acid decreased.The effects of different water stress on endogenous hormones in berries are different.Water stress could increase abscisic acid and salicylic acid content and decrease jasmonic acid content.Principal component analysis showed that water stress was most closely related to endogenous hormones abscisic acid and salicylic acid.Correlation analysis showed that resveratrol content was positively correlated with salicylic acid content.These results suggest that hormone salicylic acid may be the main signal molecule for resveratrol synthesis induced by water stress in grapevines.(3)Effects of water stress on enzyme activity related to resveratrol biosynthesis in grape berries.The PAL enzyme activity of grape berries changed greatly into berries ripening,and decreased first and then increased on the whole.The activity of C4H and 4CL enzyme increased first and then decreased,and the activity of STS enzyme increased by degrees from berries ripening.The effects of different water stress on the activities of resveratrol biosynthesis related enzymes at different berries growth stages were different.The activities of C4H and STS enzymes were significantly increased in T1 before veraison,while PAL and 4CL enzymes were increased in T2 group from veraison to maturity.The correlation analysis showed that water stress increased the correlation between PAL enzyme activity and resveratrol content,while STS enzyme activity was positively correlated with resveratrol content of T2 group.(4)Effects of water stress on resveratrol biosynthesis related genes in grape berries.Genes encoding PAL,4CL and STS were abundantly expressed after berries veraison.There were differences in the contents of grape resveratrol in response to different levels of water stress,all of which could improve the contents of resveratrol and the transcriptional levels of related genes involved in resveratrol synthesis pathway.Water stress could significantly promote the expressions of PAL and STS genes in the early and late stages of veraison,but greatly decreased the transcription level of CHS gene.Correlation analysis showed that there was a significant positive correlation between resveratrol content and the transcription levels of PAL and STS genes.Therefore,it could be inferred that water stress could increase the content of resveratrol in grape berries by inducing the expression of PAL,STS genes of resveratrol synthesis based on the data from the transcriptional level of resveratrol biosynthesis related genes and resveratrol contents.