Effects Of Water Stress On Content Of Anthocyanin And Expression Of Genes Associated With Anthocyanin Synthesis In Cabernet Sauvignon Grape

To study the effect of water stress on the anthocyanin of wine grape,the present study took the 3 a wine grape "Cabernet Sauvignon" as the experimental material and designed three-gradient stress treatments(i.e.mild water stress(T1),moderate water stress(T2),and heavy water stress(T3))according to the basic water potential of the leaf(Ψb),with non-stress treatment as the control(CK).During the ripening of grape,the relevant indicators of fruit quality were assessed,and high-performance liquid chromatography(HPLC)was used to conduct quantitative analysis on the anthocyanin of grape skin,and the genes related to anthocyanin synthesis in grape skin were preliminary studied by using real-time fluorescent quantitative PCR technology.The results showed:(1)Water stresses,regardless of degree,all reduced the hundred-grain weight of the grape.The greater the water stress,the lower the hundred-grain weight of the grape.(2)Appropriate water stress can improve the fruit quality of grape,among which the treatment with mild water stress(T1)yielded the best comprehensive effect.When compared with the control treatment(CK),its soluble solids increased by 10.34%,the soluble total sugar increased by 14.95%,reducing sugar increased by 5.96%,organic acids decreased by 5.01%,tannins increased by 27.48%,total phenols increased by 35.21%,and total anthocyanins increased by 11.2%.Treatment with moderate water stress(T2)not only reduce the content of total phenol,but also promote the quality of grape fruit,while treatment with heavy water stress(T3)lowered the quality of the fruit.(3)Five anthocyanins,including Dp-3-O-glu,Cy-3-O-glu,Pt-3-O-glu,Pn-3-O-glu,and Mv-3-O-glu,were affected by water stress.Treatments with mild(T1)and moderate(T2)water stresses can increase the contents of these five anthocyanins to different degrees.Treatment with heavy water stress(T3)would reduce the contents.The contents under the treatment with mild water stress(T1)were significantly higher than those under the control treatment(CK).Under the treatment with mild water stress(T1),the content of Dp-3-O-glu increased by 38.81%,the content of Cy-3-O-glu increased by 85.89%,the content of Pt-3-O-glu increased by 59.79%,the content of Pn-3-O-glu increased by 42.03%,and the content of Mv-3-O-glu increased by 71.85%.(4)Appropriate water stress can up-regulate the expressions of structural genes(PAL,CHS1,DFR,F3’H,F3 ’5 ’H,UFGT)related to anthocyanin synthesis and regulator gene MybAl,(during entire or part of the sampling period).Under the treatments with different degrees of water stress,the expression levels of PAL and DFR in the entire stage of fruit ripening were basically all increased.Under the treatment with mild water stress(T1),the up-regulated expression of PAL was the most significant.The up-regulated expression of F3 ’H and F3 ’5 ’H by water stress occurred mainly during the transition period from coloration to 90d after flowering,and the treatment with mild water stress(T1)produced better effect.Under the treatments with mild(T1)and moderate(T2)water stresses,the expression of UFGT and MybAl was up-regulated during the entire period from coloration to maturation.The up-regulated expression of CHS1 triggered by water stress happened mainly in the middle and late stages of fruit ripening.