Transcription factors FtMYB22 negatively regulates anthocyanin synthesis by forming an MBW ternary complex in Tartary buckwheat

Abstract Anthocyanins are important flavonoid compounds that are abundant in Tartary buckwheat, providing a variety of bright colors and enhancing abiotic stress resistance. Our study found that FtMYB22 specifically affected anthocyanin anabolism. In this study, overexpression of the FtMYB22 transcription factor in tobacco significantly reduced the accumulation of flavonol in the petals of transgenic tobacco plants. Moreover, it significantly downregulated the expression of the genes involved in anthocyanin biosynthesis in tobacco. Overexpression of the FtMYB22 transcription factor in Tartary buckwheat hairy roots significantly inhibited anthocyanin and total flavonoids biosynthesis, and downregulated the expression of the anthocyanin biosynthesis genes. Comparing wild‐type and transgenic hairy roots, FtMYB22 overexpression significantly inhibited anthocyanin accumulation and downregulated most flavonoid synthesis pathway gene expression. Yeast two‐hybrid assays demonstrated that FtMYB22 could interact with the FtbHLH family member FtTT8 and the FtWD40 family member FtTTG1 to form a ternary MBW complex to inhibit anthocyanin synthesis. Therefore, FtMYB22 can be exploited as a target site for further gene editing and molecular breeding to improve the resilience and quality of Tartary buckwheat.