Genome-wide identification of the MYB gene family and identification of candidate genes that involved in anthocyanin synthesis in cowpea (Vigna unguiculata [L.] Walp)

MYB transcription factors are important for plant growth development and abiotic stress response, especially in anthocyanin synthesis. However, the comprehensive genome-wide analysis of the MYB gene family in cowpea is unclear. In this study, 227 VuMYB genes were identified in cowpea, including 62 1R-VuMYB, 161 2R-VuMYB, and 4 3R-VuMYB. Phylogenetic analysis showed that 2R-VuMYB genes could be divided into 26 groups, where members of the same subfamily exhibited relatively conserved motifs. The co-linearity analysis showed that 66 segmental duplication events were found in VuMYB genes, and 130 orthologous groups were identified among MYB synteny genes in legume plants. By comparative transcriptome and protein interaction analysis, 2 genes (VuMYB84 and VuMYB132) were identified as potentially involved in cowpea pod anthocyanin synthesis. Subcellular localization and transcriptional activation experiments showed that VuMYB84 and VuMYB132 located in the nucleus, which had transcriptional activation activity. Sequence analysis and yeast two-hybridization showed that VuMYB84 and VuMYB132 contained WER motifs (DEEDLIIRLHKLLGNRWSLIAGR), which could interact with VubHLH3. In conclusion, our results provide a systematic analysis of the VuMYB gene family and ideas for the VuMYB gene family's involvement in the regulation of cowpea anthocyanin biosynthesis.