R2 and R3 MYB repeats are highly conserved across all R2R3-MYB proteins in the soybean genome. The sequence logos of the R2 (a) and R3 (b) MYB repeats are based on full-length alignments of all soybean R2R3-MYB domains. Multiple alignment analysis of 244 soybean-typical R2R3-MYB domains was performed with ClustalW (for full representation of the alignment, see Additional file 2). The bit score indicates the information content for each position in the sequence. Asterisks indicate the conserved tryptophan residues (Trp) in the MYB domain.