Abstract
The role of MYBA transcription factors in anthocyanin biosynthesis has been established in many plants including grapevine (Vitis vinifera L.); however, not all of the target genes of MYBAs in grapevine have been elucidated. The aim of this study was therefore to identify targets of VvMYBAs by using berry skin from a red grape (Pinot Noir) and its white mutant (Pinot Blanc), and from white grapes (Italia and Muscat of Alexandria) and their red mutants (Benitaka and Flame Muscat). First, microarray and reverse-transcription real-time PCR data revealed that, in addition to the anthocyanin specific biosynthetic genes, i.e. UDP-glucose flavonoid:3-O-glucosyltransferase (UFGT) and O-methyltransferase (OMT), a gene involved in anthocyanin transfer into vacuoles, i.e. glutathione S-transferase (GST), as well as flavonoid-3’,5’-hydroxylase (F3’,5’H) were highly upregulated in red grapes. From collective findings, it is likely that these genes are probably induced only by VvMYBAs. By contrast, genes involved in upstream flavonoid biosynthesis, such as phenylalanine ammonia-lyase (PAL), chalcone synthase 3 (CHS3), flavanone-3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), and leucoanthocyanidin dioxygenase (LDOX), were expressed in white grapes and moderately upregulated in red grapes. These genes seem to be induced by both VvMYBAs and other transcription factors. The electrophoretic mobility shift assays results revealed that VvMYBA1 and/or VvMYBA2 proteins interact with the promoter region of UFGT, CHS3, and LDOX. Collectively, our findings suggest that VvMYBAs regulate the expression of all genes involved in anthocyanin biosynthesis, and that VvMYBA protein directly interacts with not only UFGT, but also CHS3 and LDOX.
Published Version
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