Genome-Wide Characterization of the Common Buckwheat B-Box Gene Family and Identification of FeBBX11 and FeBBX27 Involved in Flavonoid Biosynthesis

Flavonoids, a class of secondary metabolites in higher plants, exert a broad range of health-promoting effects by enhancing antioxidant activity. B-box (BBX) transcription factors are reportedly involved in the regulation of flavonoid biosynthesis. However, the roles and functions of common buckwheat (Fagopyrum esculentum Moench)’s BBX members in flavonoid biosynthesis remain unclear. In this study, 31 FeBBX members were identified and divided into five subgroups. Multiple cis-elements responsive to light, hormone, and stress signals were found in the promoter regions of these members, and transcriptome data showed two different expression patterns of FeBBX11 and FeBBX27 induced by light. Subcellular location localized FeBBX11 and FeBBX27 proteins in the nucleus. The overexpression of FeBBX11 and FeBBX27 in common buckwheat enhanced its flavonoid biosynthesis and antioxidant activity. These results provide a foundation for further research on the regulatory role of the BBX gene family in flavonoid biosynthesis.