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 (Solanum tuberosum L.), a herbaceous annual of the Solanum genus in the Solanaceae 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 StPODs genes were identified in the potato genome and named StPOD1-StPOD148 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 StPODs 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 StPODs 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 StPODs were induced by plant hormone treatments, including abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA3), and benzylaminopurine (BAP), with 85 StPODs 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 StPODs 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 Saccharomyces cerevisiae, and functional analysis confirmed that StPOD23 and StPOD53 are involved in osmoregulatory responses in yeast cells. These findings provide a theoretical foundation for future functional studies of StPODs genes.