MybA1 gene diversity across the Vitis genus.

The MybA1 gene in the genus Vitis encodes a transcription factor, belonging to the R2R3 Myb family, that controls the last steps in the anthocyanins biosynthesis pathway. Polymorphism within MybA1 has been associated with color variation in berries of V. vinifera and other Vitis species. In this work, we analyzed the sequence variation in MybA1 both in the subg. Muscadinia and in an extended set of Asian, American and European genotypes of subg. Vitis. Our aims were to infer the evolution of this gene during the speciation process and to identify polymorphisms that could potentially generate changes in gene regulation. The results show that MybA1 experienced many insertions and deletions in non-coding regions but also in the third exon sequence. Owing to the larger set of Vitis species compared here, new indels were identified and the origin of previously described indels was reconsidered. A large number of single nucleotide polymorphisms were found in non-coding regions but also in the sequence coding for the R2R3 domain and the C terminal part of the protein. Some of these changes led to amino acid substitutions and therefore could have modified MybA1 protein activity. Bayesian phylogenetic analysis of all polymorphisms did not provide a consensus tree depicting the geographical partitioning of the species but allowed highlighting several species relationships within subgenus Vitis. Finally, the evolutionary events described could be useful to gain more insight into the role of MybA1 for anthocyanin biosynthesis in grapevine.