Genome-wide association study identifies loci influencing resistance to Edwardsiellosis in olive flounders (Paralichthys olivaceus)

The olive flounder (Paralichthys olivaceus) is one of the most economically important fish species in South Korea’s aquaculture industry. However, Edwardsiellosis, caused by Edwardsiella tarda (E. tarda), poses a significant threat to this industry, resulting in high mortality rates and economic losses. The aim of this study is to identify genetic loci associated with Edwardsiellosis resistance in olive flounder using a genome-wide association study (GWAS). A challenge experiment was conducted, infecting 2,939 flounders with E. tarda and recording survival traits. Genotyping was performed using a 60K SNP array, followed by statistical genetic analysis using SPACox software, which identified four significant SNPs on chromosomes 10, 13, 18, and 21. These SNPs were located in or near positional candidate genes for inflammation and immune responses, such as STXBP5L, MEF2D, and HOMER1, indicating their potential involvement in bacterial defense mechanisms. Biological pathway analysis revealed several significant pathways, including Apelin signaling, ECM-receptor interaction, Calcium signaling, and PI3K-Akt signaling, which are known to regulate immune cell activity and inflammation. These findings provide important insights into the genetic mechanisms of disease resistance in olive f lounder and offer valuable resources for future selective breeding programs aimed at enhancing Edwardsiellosis resistance.