Genome-wide identification and expression profiling of MYB transcription factor genes in radish(Raphanus sativus L.)

Radish(Raphanus sativus L.), an important root vegetable crop of the Brassicaceae family, has a high level of anthocyanin accumulation in its pigment root tissues. It was reported that MYB transcription factors(TFs) play vital roles in plant development and anthocyanin metabolism, and the PAP1/2 could promote expression of anthocyanin biosynthesis genes. In this study, a total of 187 radish MYB genes(Rs MYBs) were identified in the radish genome and clustered into 32 subfamilies. Among them, 159 Rs MYBs were localized on nine radish chromosomes. Interestingly, 14 Rs MYBs exhibited differential expression profiles in different taproot developmental stages among four differently colored radish lines. A number of Rs MYBs were highly expressed in the pigmented root tissues at the maturity stage, several genes including Rs MYB41, Rs MYB117, and Rs MYB132 being homologous to PAP1/2, showed high expression levels in the red skin of NAU-YH(red skin-white flesh) taproot, while Rs MYB65 and Rs MYB159 were highly expressed in the purple root skin of NAU-YZH(purple skin-red flesh), indicating that these Rs MYBs might positively regulate the process of anthocyanin accumulation in radish taproot. These results would provide valuable information for further functional characterization of Rs MYBs, and facilitate clarifying the molecular mechanism underlying anthocyanin biosynthesis in radish.