Genome-Wide Identification of PP2C Gene Family in Oat (Avena sativa L.) and Its Functional Analyses in Response to ABA and Abiotic Stresses.

Plant protein phosphatase 2C (PP2C) represents the largest and most functionally diverse group of protein phosphatases in plants, playing pivotal roles in regulating metabolic processes, hormone signaling, stress responses, and growth regulation. Despite its significance, a comprehensive genome-wide analysis of the PP2C gene family in oat (Avena sativa L.) has remained unexplored. Leveraging the recently published oat genome, we identified 194 AsaPP2C genes, which were unevenly distributed across all 21 chromosomes. A phylogenetic analysis of PP2C classified these genes into 13 distinct subfamilies (A-L), with conserved motif compositions and exon-intron structures within each subfamily, suggesting evolutionary functional specialization. Notably, a promoter analysis revealed an abundance of stress-responsive cis-regulatory elements (e.g., MYB, MYC, ARE, and MBS), implicating AsaPP2Cs in hormones and biotic stress adaptation. To elucidate their stress-responsive roles, we analyzed transcriptomic data and identified seven differentially expressed AsaPP2C (Asa_chr6Dg00217, Asa_chr6Ag01950, Asa_chr3Ag01998, Asa_chr5Ag00079, Asa_chr4Cg03270, Asa_chr6Cg02197, and Asa_chr7Dg02992) genes, which were validated via qRT-PCR. Intriguingly, these genes exhibited dynamic expression patterns under varying stress conditions, with their transcriptional responses being both time-dependent and stress-dependent, highlighting their regulatory roles in oat stress adaptation. Collectively, this study provides the first comprehensive genomic and functional characterization of the PP2C family in oat, offering valuable insights into their evolutionary diversification and functional specialization.