The myb transcription factor MdMYB6 suppresses anthocyanin biosynthesis in transgenic Arabidopsis

The R2R3-Myb proteins comprise a large family of plant transcription factors that regulate the expression of multiple drought-responsive and cold-responsive genes by binding special cis-elements at the promoter. There have been previous studies in transgenic plant over-expression of the myb protein. In this article, we analyzed the function of MdMYB6, an R2R3-type Myb transcription factor from apples (Malus x domestica), in transgenic Arabidopsis plants. In contrast to wild type plants, these transgenic lines accumulated less anthocyanin. Equimolar concentrations of sorbitol did not alter the anthocyanin accumulation. Real-time polymerase chain reaction (PCR) indicated that MdMYB6 over-expression suppressed enzymes involved in anthocyanin biosynthesis and some Arabidopsis basic helix-loop-helix (bHLH) genes. The MdMYB6 transcription faction may be an important repressor of anthocyanin biosynthesis in plants.