Genome-wide identification, characterization, and expression analysis of the glutathione peroxidase (GPX) gene family in Siniperca chuatsi.

Glutathione peroxidases (GPXs) are key antioxidant enzymes that maintain cellular redox homeostasis by reducing reactive oxygen species. However, the genomic organization, evolutionary relationships, and baseline expression profiles of the GPX gene family remain poorly characterized in the commercially important freshwater fish Siniperca chuatsi. In this study, a genome-wide identification and comparative analysis of gpx genes was performed using the S. chuatsi reference genome together with GPX proteins from 36 representative animal species. Seven gpx genes (gpx1b, gpx2, gpx3, gpx4a, gpx7, gpx8, and gpx9) were identified, whereas gpx5 and gpx6 were absent. Phylogenetic analysis grouped GPX proteins into five major clades consistent with the recognized species GPX subfamilies and supported the orthology of the identified S. chuatsi genes. Conserved motif and domain analyses showed that GPX proteins retain the characteristic glutathione peroxidase catalytic domain and a conserved thioredoxin-like structural fold. Chromosomal mapping demonstrated that the seven genes are distributed across six chromosomes. Protein-protein interaction analysis based on zebrafish orthologs revealed a significantly interconnected network enriched for oxidative stress-related biological processes. Transcriptome analysis further demonstrated distinct tissue- and developmental stage-associated expression patterns, with gpx4a and gpx9 showing relatively higher expression in digestive tissues, gpx3 displaying its highest expression at the morula stage, and gpx1b and gpx7 exhibiting distinct expression profiles across adult tissues and developmental stages. Collectively, these findings provide a comprehensive genomic and transcriptomic characterization of the GPX gene family in S. chuatsi and establish a valuable resource for future studies investigating GPX evolution and biological function in teleost fishes.