The neighbor-joining tree includes 158 R2R3-MYB proteins from maize, 126 R2R3-MYB proteins from Arabidopsis, and a further 52 R2R3-MYB proteins from other plant species. The proteins are clustered into 37 subgroups (triangles), designated with a subgroup number (e.g., G1). Subfamilies are represented as collapsed triangles, with depth and width proportional to sequence divergence and size, respectively. The black triangles indicate that the subgroup includes ZmMYBs and AtMYBs; the hatched and white triangles indicate that the subgroup includes or excludes ZmMYBs, respectively. Bootstrap values <50% are not shown in the phylogenetic tree. Four proteins did not fit well into clusters. The first 25 subgroups were designated as previously reports of AtMYBs by Stracke et al. (2001) and Dubos et al. (2010). The subgroups were listed in round bracket with annotated functions, for reference. 12 new subgroups were added because of the increased data set.