Change of Phytoalexin Stilbenoids of Grape Skin Rkatsiteli (Vitis vinifera I.) in Condition of Powdery Mildew

It has been studied a change of Georgian genome main white vine variety Rkatsiteli grape skin phytoalexins- stilbenoids in the condition of the disease Powdery mildew (Uncinula nec.). The samples of health and infected grapes–with 50% Powdery mildew, were taken in Beginning of September in 2018 year until the technical maturity, from the same vineyard planted in eastern Georgia. The vineyard soil belongs to meadow cinnamonic –Calcaric cambisols and calcic kastanozems type.Vineyard is 32 years old. Based on the HPLC/MS analysis are established the stilbenoids profiles of healthly and infected skins and has been revealed phytoalexin stylbenoids - accumulated as a result of the action of downy mildew. The concentration of stilbenoids increased during the diseases. The dominant stress-metabolites Stilbenoides are trans- resveratrol and trans-ε-viniferin. At the same time it was revealed as stress-metabolites: trans-piceid, cis-piceid, trans-piceatannol and oligomeric stilbenoids. The variability of these stilbenoids concentrations in the condition of the disease -Powdery mildew,is different: trans-resveratrol 27.7mg/ kg→58.92 mg/ kg(53,0%); trans-ε-viniferin 11.22 mg /kg→32.55mg /kg(65,5%); trans-piceid 5.36 mg/ kg→7.27mg /kg(26,3%) ; trans-piceatannol 1.45mg/ kg→2.04 mg/ kg(28,9%); cis-piceid 17.75 mg/kg→17.79 mg/kg( 0,2%); trans-astringin 14.45mg/kg →16.93 mg/kg(12,9%); cis-astringin 15.02 mg/kg→16.78 mg/kg(10,5%). The stress-metabolite stilbenoids in the conditions of the disease with Powdery mildew, is a scientific novelty for the grape of Rkatsiteli variety. The results of the research are important for determination the correlation of the vine immunity with the phytoalexins-stilbenoids.