MYB Superfamily in : Evidence for Hormone-Mediated Expression Profiles, Large Expansion, and Functions in Root Hair Development.

MYB proteins are involved in diverse important biological processes in plants. Herein, we obtained the superfamily from the allotetraploid , which contains 227 -related (/), 429 (), 22 (), and two () genes. Phylogenetic analysis classified the Bn2R-MYBs into 43 subfamilies, and the BnMYBRs into five subfamilies. Sequence characteristics and exon/intron structures within each subfamily of the s and s were highly conserved. The whole superfamily was unevenly distributed on 19 chromosomes and underwent unbalanced expansion in . Allopolyploidy between and mainly contributed to the expansion in their descendent , in which -derived genes were more retained. Comparative phylogenetic analysis of 2R-MYB proteins from nine Brassicaceae and seven non-Brassicaceae species identified five Brassicaceae-specific subfamilies and five subfamilies that are lacking from the examined Brassicaceae species, which provided an example for the adaptive evolution of the 2R-MYB gene family alongside angiosperm diversification. Ectopic expression of four s under the control of the viral and/or native promoters could rescue the lesser root hair phenotype of the mutant plants, proving the conserved negative roles of the s of the S15 subfamily in root hair development. RNA-sequencing data revealed that the s and s had diverse transcript profiles in roots in response to the treatments with various hormones. Our findings provide valuable information for further functional characterizations of genes.