Genome-Wide Identification of R2R3-MYB Transcription Factor and Expression Analysis under Abiotic Stress in Rice

The myeloblastosis (MYB) family comprises a large group of transcription factors (TFs) that has a variety of functions. Among them, the R2R3-MYB type of proteins are the largest group in plants, which are involved in controlling various biological processes such as plant growth and development, physiological metabolism, defense, and responses to abiotic and biotic stresses. In this study, bioinformatics was adopted to conduct genome-wide identification of the R2R3-MYB TFs in rice. We identified 190 MYB TFs (99 R2R3-MYBs), which are unevenly distributed on the 12 chromosomes of rice. Based on the phylogenetic clustering and protein sequence characteristics, OsMYBs were classified into five subgroups, and 59.6% of the Os2R_MYB genes contained two introns. Analysis of cis-acting elements in the 2000 bp upstream region of Os2R_MYB genes showed that all Os2R_MYB genes contained plant hormones-related or stress-responsive elements since 91.9%, 79.8%, 79.8%, and 58.6% of Os2R_MYB genes contain ABRE, TGACG, CGTCA, and MBS motifs, respectively. Protein-protein network analysis showed that the Os2R_MYBs were involved in metabolic process, biosynthetic process, and tissue development. In addition, some genes showed a tissue-specific or developmental-stage-specific expression pattern. Moreover, the transcription levels of 20 Os2R_MYB genes under polyethylene glycol (PEG) and cadmium chloride (CdCl₂) stress inducers were dissected by qRT-PCR. The results indicated genes with an altered expression upon PEG or CdCl₂ stress induction. These results potentially supply a basis for further research on the role that Os2R_MYB genes play in plant development and stress responses.