Identification and functional analysis of glutathione S-transferase gene family in Trachinotus ovatus: Transcriptomic response to environmental and pathogenic stress

Glutathione S-transferases (GSTs) are a class of enzymes that perform a wide range of biological functions, particularly playing central roles in detoxification, antioxidant processes, and protecting against environmental and pathogen stresses. In this study, we conducted a comprehensive genomic analysis of the GST gene family in Trachinotus ovatus, identifying a total of 14 GST genes. Their chromosomal distribution, characterization, evolutionary relationships, evidence of positive selection were studied in detail. It was found that the GST genes are evolutionarily conserved. Phylogenetic analyses revealed that these genes are distributed into three subgroups: cytosolic GSTs, mitochondrial GSTs, and membrane-associated proteins in eicosanoid and glutathione metabolism (MAPEG). We further explored the physiological responses of these genes to hypoxic stress and exposure to bacterial pathogens, particularly noting the significant up-regulation of ToGSTT1, ToGSTT2, ToGSTK1b, and ToGSTT3 during reoxygenation of gill tissues, as well as the relevance of ToGSTK1a and ToGSTK1b in immunomodulation in response to both Streptococcus agalactiae and Cryptocaryon irritans infections. This study enhances our understanding of the functional characteristics of the GST gene family in T. ovatus and provides new insights into its roles in antioxidative stress and immune response mechanisms.