Wine grape (Vitis vinifera L.) color associates with allelic variation in the domestication gene VvmybA1

During the process of crop domestication and early selection, numerous changes occur in the genetic and physiological make-up of crop plants. In grapevine (Vitis vinifera) numerous changes have occurred as a result of human selection, including the emergence of hermaphroditism and greatly increased variation in berry color. This report examines the effect of human selection on variable skin color by examining the variation present in the gene VvmybA1, a transcriptional regulator of anthocyanin biosynthesis. In over 200 accessions of V. vinifera, the insertion of the retroelement Gret1 in the promoter region of VvmybA1 was in strong association with the white-fruited phenotype. This retroelement was inserted at the same location for each individual in which it was present. Additional polymorphisms in the VvmybA1 gene were also strongly associated with red or pink fruited accessions, including variation that was generated by the excision of Gret1 from the promoter of VvmybA1. Differences in nucleotide diversity were observed between the white and pigmented alleles of VvmybA1, suggesting that the white allele arose only once or a limited number of times. Rarely, association of Gret1 with the white fruited phenotype was not observed, suggesting that the white phenotype can also be obtained through mutation in additional genes. These results provide evidence that variation in one transcriptional regulator has generated an allelic series strongly associated with fruit color variation in cultivated grapevine. These findings provide information about the evolution of grapes since domestication and have direct implications for the regulation of fruit and wine quality of this important crop plant.