Association of VvmybA1 gene expression with anthocyanin production in grape (Vitis vinifera) skin-color mutants

Abstract

By using white-skinned cultivars ('Italia' and 'Muscat of Alexandria') and putative red-skinned sports ('Ruby Okuyama' and 'Flame Muscat') from the white cultivars, we analyzed the expression and function of a myb-related gene, VvmybA1, involved in the regulation of anthocyanin biosynthesis in grapes. A simple sequence repeat (SSR) analysis showed that 'Ruby Okuyama' and 'Flame Muscat' are true derivatives by bud mutation from 'Italia' and 'Muscat of Alexandria', respectively. The VvmybA1 transcript was detected in berry skins of 'Ruby Okuyama' after coloring had begun; it was not detectable in those of 'Italia'. Three VvmybA cDNAs (VvmybA1, VvmybA2, and VvmybA3) from 'Ruby Okuyama' under the control of the 35S promoter were introduced into somatic embryos of 'Kyoho' by particle bombardment. Upon the introduction of VvmybA1, red cells were induced in the embryos, whereas the introduction of VvmybA2 or VvmybA3 failed to do so. The VvmybA1 cDNA was also shown to have the ability to induce the anthocyanin-producing cells in the skin tissues of 'Muscat of Alexandria'. The relationship between the skin-color mutations and the detailed structure of the VvmybA1 gene is also described.