FtMYB163 Gene Encodes SG7 R2R3-MYB Transcription Factor from Tartary Buckwheat (Fagopyrum tataricum Gaertn.) to Promote Flavonol Accumulation in Transgenic Arabidopsis thaliana

Tartary buckwheat (<i>Fagopyrum tataricum</i> Gaertn.) is a coarse grain crop rich in flavonoids that are beneficial to human health because they function as anti-inflammatories and provide protection against cardiovascular disease and diabetes. Flavonoid biosynthesis is a complex process, and relatively little is known about the regulatory pathways involved in Tartary buckwheat. Here, we cloned and characterized the <i>FtMYB163</i> gene from Tartary buckwheat, which encodes a member of the R2R3-MYB transcription factor family. Amino acid sequence and phylogenetic analysis indicate that FtMYB163 is a member of subgroup 7 (SG7) and closely related to FeMYBF1, which regulates flavonol synthesis in common buckwheat (<i>F. esculentum</i>). We demonstrated that FtMYB163 localizes to the nucleus and has transcriptional activity. Expression levels of <i>FtMYB163</i> in the roots, stems, leaves, flowers, and seeds of <i>F. tataricum</i> were positively correlated with the total flavonoid contents of these tissues. Overexpression of <i>FtMYB163</i> in transgenic <i>Arabidopsis</i> enhanced the expression of several genes involved in early flavonoid biosynthesis (<i>AtCHS</i>, <i>AtCHI</i>, <i>AtF3H</i>, and <i>AtFLS</i>) and significantly increased the accumulation of several flavonoids, including naringenin chalcone, naringenin-7-O-glucoside, eriodictyol, and eight flavonol compounds. Our findings demonstrate that FtMYB163 positively regulates flavonol biosynthesis by changing the expression of several key genes in flavonoid biosynthetic pathways.