M: Identification and characterization of R2R3-MYB and bHLH transcription factors regulating anthocyanin biosynthesis in gentian flowers. Plant & cell physiology 2008

Gentian plants have vivid blue-colored flowers, caused by accumulation of a polyacylated anthocyanin ‘gentiodelphin’. We previously performed expression analysis of gentiodelphin biosynthetic genes, and hypothesized that the white-flowered gentian cultivar ‘Polarno White ’ might have resulted from the mutation of certain regulatory factors responsible for antho-cyanin biosynthesis in flower petals. In this study, we isolated 26 R2R3-MYB gene fragments including four full-length cDNAs (GtMYB2a, GtMYB2b, GtMYB3 and GtMYB4) and one basic helix–loop–helix (bHLH) gene (GtbHLH1) from blue-flowered gentian by degenerate PCR and rapid ampli-fication of cDNA ends (RACE). Phylogenetic tree analysis showed that GtMYB3 was categorized into a clade involved in anthocyanin biosynthesis including petunia AN2 and Arabi-dopsis PAP1. On the other hand, GtbHLH1 exhibited hig