Study On Sugars And Acids Composition, Inheritance And Sucrose Metabolism Related Enzymes Activities In Grape Berries

Sugars and organic acids content in grape berries of 98 cultivars and four unselected crosses progenies populations were detected during two successive years. Sugars content and enzymes activities relating sucrose metabolism in grape berries and leaves were detected during grape ripening with different sucrose content cultivars. The main results were as following:Glucose and fructose were the predominant sugars in grape berries and ranged from 45.86 to 122.89 mg ml-1, and 47.64 to 131.04 mg ml-1, respectively, in two years. Sucrose content was present at trace amounts in most cultivars. Meanwhile, two high sucrose content cultivars, Honey juice and B180, and a low sucrose content cultivar, Canadice, were detected. Tartaric acid content in berries ranged from 1.54 to 9.09 mg ml-1; malic acid content in grape berries ranged from 0.36 to 7.06 mg ml-1. Tartaric acid content was significantly higher than malic acid content. Significantly higher total soluble sugars and fructose and lower total acids and malic acid were found in cultivars from hybrids between V. labrusca and V. vinifera than those in V. vinifera cultivars, and wine grapes had higher total sugars and acids than table grapes from V. vinifera.Principal component analysis (PCA) indicated that PC1 was highly connected with glucose and fructose contents, and sucrose was an important contributor to the variance for PC2, as well as for PC3. PC2 and PC3 were highly connected with organic acids, but the contribution to variance differed one year from the other. Sugars contents in grape berries were stable between years, while organic acid contents were more variable during different years.The broad sense heritability of glucose content in grape berries ranged from 0.65 to 0.87, and that of fructose ranged from 0.51 to 0.71, total sugar heritability ranged from 0.61 to 0.8. The means of progenies sugar content were lower than mean of parent values. Malic acid content was strongly additive inheritance and the broad-sense heritability range from 0.35 to 0.98. The means of progenies malic acid content were higher than mean of parent values. Tartaric acid content was mainly controlled by non-additive effect and the broad sense heritability ranged from 0.07 to 0.91. Mean of progenies tartaric acid content was lower than mean of parent value. The total acid content was strongly additive inheritance and was mainly influenced by malic acid. The broad-sense heritability of total acid ranged from 0.45 to 0.98.Principal component analysis (PCA) results showed that glucose and fructose were the first PC and explained 47% to 54% of the total variance. Total acid and malic acid represent the second PC and explained 24% to 26% of the total variance. The total acid difference among cross progenies was mainly influenced by malic acid variance. There was no difference on sugar and acid heritability betweenreciprocal cross progenies.Sucrose content in grape berries was highly negatively related with acid invertase activity. Acid invertase activities in berries of high sucrose content cultivars were significantly lower than that of trace sucrose content cultivars. Acid invertase activities in berries of low sucrose content cultivars were significantly lower than that of trace sucrose content cultivars but higher than that of high sucrose content cultivars.There were no significantly different concerning neutral invertase, sucrose phosphate synthase, andsucrose synthase activities in berries of all cultivars used in this study, and there were also no significantly different for sugars contents and enzyme activities relating sucrose-metabolism in leaves of the used cultivars. It is suggested that the sucrose content difference in grape berries is owing to the activities difference of acid invertase in vacuole of berries; sucrose was cleaved to glucose and fructose by acid invertase after transported into vacuole. Sucrose accumulation in grape berries did not suppress sugar transportation into berries.The increment of acid invertase activities preceded sugar accumulation in grape berries. Th...