Genome-wide association study of VHSV-resistance trait in Paralichthys olivaceus

In flounder aquaculture, selective breeding plays a vital role in the development of disease-resistant traits and animals with high growth rates. Moreover, superior animals are required to achieve high profits. Unlike growth-related traits, disease-resistant experiments need to be conducted in a controlled environment, as the improper measurement of traits often leads to low genetic correlation and incorrect estimation of breeding values. In this study, viral hemorrhagic septicemia virus (VHSV) resistance was studied using a genome-wide association study (GWAS), and the genetic parameters were estimated. Genotyping was performed using a high-quality 70 K single nucleotide polymorphism (SNP) Affymetrix® Axiom® myDesign™ Genotyping Array of olive flounder. A heritability of ∼0.18 for resistance to VHSV was estimated using genomic information of the fish. According to the GWAS, significant SNPs were detected in chromosomes 21, 24, and contig AGQT02032065.1. Three SNPs showed significance at the genome-wide level (p < 1 × 10^-6), while others showed significance above the suggestive cutoff (p < 1 × 10^-4). The 3% phenotypic variation was explained by the highest significant SNP, named AX-419319631. Of the important genes for disease resistance, SNPs were associated with plcg1, epha4, clstn2, pik3cb, hes6, meis3, prx6, cep164, siae, and kirrel3b. Most of the genes associated with these SNPs have been previously reported with respect to viral entry, propagation, and immune mechanisms. Therefore, our study provides helpful information regarding VHSV resistance in olive flounder, which can be used for breeding applications.