Comprehensive genome-wide identification and expression analysis of the EPF/EPFL gene family in oat

Epidermal pattern factor-like (EPF/EPFL) genes are a unique class of small, secreted peptides found in plants that play crucial roles in plant stress responses. A genome-wide analysis revealed 33 AsEPF/EPFL genes in oats (Avena sativa), with 28 containing the conserved EPF domain and 5 harbouring the stomagen domain. These proteins share 2-6 conserved motifs, reflecting functional modularity. The phylogenetic classification grouped these genes into five evolutionarily conserved clades containing both monocot and dicot homologues, indicating early divergence prior to monocot-dicot speciation. Expression profiling revealed distinct tissue-specific patterns: preferential expression in roots (12 genes), stems (6 genes), leaves (5 genes), and spikes (7 genes), with 3 genes showing dual peak expression in stems and leaves. Further analysis of gene expression under salt and drought stress revealed that AsEPF/EPFLs are induced by both types of stress, with different genes showing varying expression patterns under drought and salt stress. This study identified valuable candidate genes for high-yielding and stress-resistant oat breeding.