Genome-wide identification of the oat (Avena sativa L.) R2R3-MYB gene family and expression analysis under different abiotic stresses

Oat (Avena sativa L.), a member of the Avena genus in the Poaceae family, exhibits strong adaptability to harsh environments, including nutrient-poor soils, salinity, cold, and drought. The R2R3-MYB (v-myb avian myeloblastosis viral oncogene homologue) transcription factors form one of the most extensive transcription factor families in plants, contributing significantly to growth regulation and responses to abiotic stresses. However, the AsR2R3-MYB gene family has not yet been systematically characterized in A. sativa, and its expression patterns and potential functions under drought, cold, or salt stress remain unexplored. (2) Methods: This study identified AsR2R3-MYB genes from the A. sativa genome and examined their chromosomal distribution, gene architecture, phylogenetic relationships, protein-protein interaction networks, and promoter cis-elements. Additionally, expression profiles across various tissues and in response to different abiotic stresses were validated using qRT-PCR. (3) Results: A total of 237 AsR2R3-MYB family members were identified in this study. Based on phylogenetic analysis with Arabidopsis R2R3-MYB proteins, the 237 AsR2R3-MYBs were categorized into 29 subfamilies (A1–A29). Among these, the A1 subfamily contained the largest number of members. Protein–protein interaction analysis revealed that 45 AsMYB proteins were involved in interaction networks, with AsMYB201 exhibiting the highest number of interacting partners. Twenty AsMYB genes were expressed in all tissues with significant differences in expression levels across different organs. All 20 AsMYB genes responded to salt, drought, and cold stresses, with AsMYB204 and AsMYB107 showing significant upregulation under multiple abiotic stresses, identifying them as key candidate genes for further functional validation. (4) Conclusions: These results establish a basis for future investigation into the roles of A. sativa AsMYB genes in abiotic stress responses and offer important insights to support molecular breeding efforts aimed at enhancing stress resilience in A. sativa.