Evolution of the 3R-MYB gene family in plants

Abstract

Plant3RMYBtranscriptionfactorsareanimportantsubgroupoftheMYBsuperfamilyinplants;however,theirevolutionaryhistoryand functionsremainpoorlyunderstood.Weidentified2253R-MYBproteinsfrom65plantspecies,includingalgaeandallmajorlineagesof land plants. Twosegmental duplication events preceding the common ancestor of angiosperms have given rise to three subgroups of the 3R-MYBproteins. Five conserved introns in the domain region of the 3R-MYB geneswere identified,which arose through a stepwise pattern of intron gain during plant evolution. Alternative splicing (AS) analysis of selected species revealed that transcripts from more than60%of3R-MYBgenesundergoAS.AS could regulate transcriptional activity for someof theplant3R-MYBsbygenerating different regulatory motifs. The 3R-MYB genes of all subgroups appear to be enriched for Mitosis-Specific Activator element core sequenceswithintheirupstreampromoterregion,whichsuggestsafunctionalinvolvementincellcycle.Notably,expressionof3R-MYB genes from different species exhibits differential regulation under various abiotic stresses. These data suggest that the plant 3R-MYBs function in both cell cycle regulation and abiotic stress response,whichmaycontribute to the adaptation of plants to a sessile lifestyle.