Genome-wide identification of class III POD gene family in potato and its expression profile analysis

Class III peroxidases (EC 1.11.1.7) are plant-specific oxidoreductases widely distributed across plant species. They catalyze redox reactions between hydrogen peroxide (H₂O₂), serving as an electron acceptor, and various electron donors, playing a critical role in plant responses to diverse environmental stresses. Potato (<italic>Solanum tuberosum</italic> L.), a herbaceous annual of the <italic>Solanum</italic> genus in the <italic>Solanaceae</italic> family, has seen limited functional research on its peroxidase (POD) gene family (StPODs). In this study, we conducted a comprehensive bioinformatics analysis of the StPODs gene family to explore their expression patterns under various abiotic stresses. A total of 148 <italic>StPODs</italic> genes were identified in the potato genome and named <italic>StPOD1-StPOD148 </italic>based on their chromosomal positions. These StPODs proteins ranged from 76 to 914 amino acids in length, and molecular weights ranging from 83.64 to 101.32 kD. Functional analyses based on conserved motifs and structural domains revealed that all <italic>StPODs </italic>contained five highly conserved motifs (Motifs 1-5) and two conserved domains: secretory_peroxidase and PLN03030 superfamily. Microarray data were used to analyze their expression profiles under stress conditions. Many <italic>StPODs</italic> showed significantly increased expression in response to salt, drought, and high temperature stresses, with the highest number of differentially expressed genes (64) observed under salt stress. Additionally, several <italic>StPODs</italic> were induced by plant hormone treatments, including abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA₃), and benzylaminopurine (BAP), with 85 <italic>StPODs</italic> genes showing differential expression following ABA induction. Furthermore, by comparing expression profiles between the drought-tolerant potato line “A90” and the drought-sensitive line “A163”, 14 <italic>StPODs</italic> were identified as candidate drought-tolerance genes, showing opposite expression trends between the two lines. Six genes with the most pronounced differential expression were heterologously expressed in <italic>Saccharomyces cerevisiae</italic>, and functional analysis confirmed that <italic>StPOD23</italic> and <italic>StPOD53</italic> are involved in osmoregulatory responses in yeast cells. These findings provide a theoretical foundation for future functional studies of <italic>StPODs</italic> genes.