Genome-Wide Identification and Functional Studies of the APX Gene Family in Oat (Avena sativa L.)

Ascorbate peroxidase (APX) plays a crucial role in both the removal of hydrogen peroxide and chloroplast development in response to light. To clarify the function of the APX gene family in oat (Avena sativa L.), we identified the family members and systematically analyzed their characteristics, phylogenetic relationships, promoter cis-elements, and expression patterns. Overall, 27 oat APX (AsAPX) members were identified in oat, and all encoded products had a peroxidase or peroxidase-like heptapeptide structure and motif. The genes were distributed unevenly across 15 chromosomes, with amino acid sequences ranging from 112 to 510 and molecular weights varying between 11.83 and 55.45 kDa. A phylogenetic analysis revealed that AsAPXs can be categorized into five branches, while an intra-group syntenic analysis identified 17 pairs of duplicate segments. Furthermore, 41 cis-element recognition sites were identified in the promoter regions of AsAPX genes, primarily comprising light-responsive and phytohormone-responsive elements. Moreover, qRT-PCR results indicated that AsAPX genes respond to light. Based on these results, our research establishes a foundation for exploration of AsAPX gene functionality and offers light-inducible candidate genes for chloroplast development to enhance A. sativa and improve crop production.