Comprehensive genomic exploration of class III peroxidase genes in guava unravels physiology, evolution, and postharvest storage responses.

Peroxidases (PRXs) play multifaceted roles in plant growth, development, and stress responses. Here, we present a comprehensive analysis of the PRX gene family in guava, a globally significant fruit. In the guava genome, we identified 37 PRX genes, a number lower than that of Arabidopsis, suggesting a distinctive gene family expansion pattern. Phylogenetic analysis unveiled close relationships with Arabidopsis PRXs, with 12 PgPRX genes forming ortholog pairs, indicating a specific expansion pattern. Predictions placed most PRX proteins in the chloroplast and extracellular regions. Structural analysis of PgPRX proteins revealed commonalities in domain structures and motif organization. Synteny analysis underscored the dynamic role of segmental duplication in the evolution of guava's PRX genes. We explored the dynamic expression of PgPRX genes across guava tissues, exposing functional diversity. Furthermore, we examined changes in peroxidase levels and gene expressions during postharvest fruit storage, providing insights for preserving fruit quality. This study offers an initial genome-wide identification and characterization of Class III peroxidases in guava, laying the foundation for future functional analyses.