Genome-Wide Identification and Evolutionary and Expression Analyses

MYBproteins constituteoneof the largest transcription factor families inplants. Recent evidence revealed that MYB-related genes play crucial roles in plants. However, compared with the R2R3-MYB type, little is known about the complex evolutionary history of MYB-related proteins in plants. Here, we present a genome-wide analysis of MYB-related proteins from 16 species of flowering plants, moss, Selaginella, and algae. We identifiedmanyMYB-related proteins in angiosperms, but few in algae. Phylogenetic analysis clas-sified MYB-related proteins into five distinct subgroups, a result supported by highly conserved intron pat-terns, consensus motifs, and protein domain architecture. Phylogenetic and functional analyses revealed that the Circadian Clock Associated 1-like/R-R and Telomeric DNA-binding protein-like subgroups are>1 billion yrs old, whereas the I-box-binding factor-like and CAPRICE-like subgroups appear to be newly derived in angiosperms. We further demonstrated that the MYB-like domain has evolved under strong puri-fying selection, indicating the conservation of MYB-related proteins. Expression analysis revealed that the MYB-relatedgenefamilyhas awideexpressionprofile inmaizeandsoybeandevelopmentandplays important roles in development and stress responses. We hypothesize that MYB-related proteins initially diversified through three major expansions and domain shuffling, but remained relatively conserved throughout th