Cloning, sequence characteristics, phylogenetic analysis of <italic>FeMYB18</italic> transcription factor gene from common buckwheat and its regulatory role in anthocyanin biosynthesis

Aims: Anthocyanins contribute the red flower color, nutritional quality and abiotic/biotic stress tolerance in common buckwheat (Fagopyrum esculentum), nevertheless, its biosynthesis regulation mechanism in common buckwheat remains unclear. Methods: Here, an MYB transcription factor gene FeMYB18 was chosen through homologous alignment using Arabidopsis AtMYBL2 in common buckwheat genome data. Then, FeMYB18 was cloned from common buckwheat cultivar ‘Guihongtian 2’, and performed to sequence characteristics, phylogenetic, tis-sue-specific expression and subcellular localization analysis. Meanwhile, its function in regulation anthocyanin biosynthesis was verified by overexpression in wild Arabidopsis. Results: The results suggested that the full length CDS of FeMYB18 is 732 bp, encoding 243 amino acids, with predicted molecular weight 27.469 kDa and isoelectric point 8.76. FeMYB18 is most closely homologous to FtMYB18, which is a negative regulator of anthocyanin biosynthesis in Tartary buckwheat, and they both belong to the MYB-SG4 subfamily and contain R2, R3, suppression motif C5 and bHLH-binding conserved domains. The expression profiles of FeMYB18 were negative correlation with the anthocyanins content in stems and leaves of ‘Guihongtian 2’. FeMYB18 locates in the nucleus, and when FeMYB18 is overexpressed in Arabidopsis, no pigment accumulated in the seedlings in transgenic seedlings, and the anthocyanin content is significantly lower than that in the wild-type Arabidopsis. Meanwhile, the expression levels of the structural genes AtDFR, AtANS and AtUFGT in the anthocyanin synthesis pathway are significantly down-regulated in transgenic plants. In summary, FeMYB18 may negatively regulate anthocyanin accumulation by suppressing the expression levels of anthocyanin biosynthesis-related genes. Conclusion: These findings enrich the regulation mechanism of anthocyanin biosynthesis and lay foundation for further research on regulatory network. It will also facilitate the breeding of common buckwheat cultivars with high anthocyanin content and nutrition.