Genome-wide characterization and expression analysis of the MYB transcription factor family in mung bean (Vigna radiata)

The MYB transcription factor family is one of the largest and most functionally diverse groups of transcription factors in angiosperms. Members of this family participate in a wide array of biological processes, including root hair initiation, pollen development, seed germination, and plant responses to heat, freezing, drought, and salinity stress. To elucidate the roles of MYB transcription factors in growth, development, and stress adaptation in mung bean, we performed a genome-wide investigation and identified 209 VrMYB genes through bioinformatic analyses. These genes are unevenly distributed across the 11 mung bean chromosomes. Subgroup-specific conserved motifs were detected, and most VrMYB genes contain one to three introns. Segmental duplication appears to be the primary force driving VrMYB gene family expansion. Collinearity analysis revealed that 125 and 150 VrMYB genes exhibit orthologous relationships with Arabidopsis thaliana and Glycine max, respectively. Promoter analysis identified numerous cis-acting regulatory elements associated with growth and development, hormone signaling, and abiotic stress responses. Co-expression analysis further indicated that VrMYB genes are strongly linked with several gene families, including WRKY, WD-repeat, and bHLH. Expression profiling across developmental stages, tissues, and stress treatments demonstrated substantial divergence among the 209 genes. Four VrMYB genes (VrMYB197, VrMYB105, VrMYB206, and VrMYB109) showed consistently high expression throughout the growth cycle. Under drought and salt-alkali stress, 144 and 86 VrMYB genes were differentially expressed, respectively, with 78 genes responding to both stresses, highlighting their potential roles in stress adaptation. Together, these findings provide a comprehensive foundation for future functional characterization of the VrMYB gene family in mung bean.