Study of the relationship between the cultivars of Vitis vinifera and the white-fruited and hermaphrodite Chinese wild grapes

Chinese wild grapes are almost exclusively dioecious and black-fruited, with rare reports of white and hermaphrodite types in V. davidii. To reveal the molecular mechanisms of these phenotypic variations, specific primers were designed to detect the genotypes of mybA-related genes in Vitis species, including the Chinese wild Vitis species, V. riparia, V. rupestris, cultivars of Vitis vinifera and its hybrids. We report here that three mybA-related genes, VvmybA1a, VvmybA2 and VvmybA3, were only detected in cultivars of V. vinifera and its hybrids, but not in V. riparia, V. rupestris or Chinese wild Vitis species, indicating that these genes could be used to test the genetic relationship to V. vinifera. On the other hand, the genes were not detected in the dioecious varieties of V. davidii, but were in the hermaphrodites. In particular, the white-fruited varieties were homozygous for VvmybA1a and showed a low expression of mybA-related genes and UFGT during the entire maturation period. Simple sequence repeat analysis showed that the hermaphrodite varieties of V. davidii, including the white-fruited varieties, were more closely related to V. vinifera cv. Pinot Noir and V. labruscana cv. Kyoho. These results suggested that the white-fruited and hermaphrodite varieties of V. davidii could be the result of its crossing with V. vinifera. It provides a new approach to identify truly Chinese wild varieties and to search for possible hybridization events.