Comparison of UDP-glucose : flavonoid 3-O-glucosyltransferase (UFGT) gene sequences between white grapes (Vitis vinifera) and their sports with red skin

The expression of the UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT) gene has been shown to be critical for anthocyanin biosynthesis in the grap e berry. Using white cultivars and bud sports with red skin, we examined th e expression of seven anthocyanin biosynthetic genes including the UFGT gen e and compared the coding/promoter sequences of the UFGT gene. Northern blo t analysis showed that the seven anthocyanin biosynthetic genes were expres sed coordinately at higher levels in the red-skin sports than in the while- skin progenitors of the sports. It was especially notable that UFGT gene ex pression was detected only in the red-skin sports and Kyoho. However, there were no differences in either coding or promoter sequences between Italia (Vitis vinifera) and its red-skin sport Ruby Okuyama, or between Muscat of Alexandria (V. vinifera) and the red-skin sport Flame Muscat. From these fi ndings, the phenotypic change from white to red in the sports is thought to be the result of a mutation in a regulatory gene controlling the expressio n of UFGT. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.