Genome wide association analysis reveals the genetic sites of heat resistance in largemouth bass (Micropterus salmoides)

Largemouth bass (Micropterus salmoides) is an important commercially cultured freshwater fish. High temperature is a common challenge encountered in the summer cultivation of largemouth bass. In this study, we conducted a genome-wide association study using general linear models and linear mixed models to identify significant single nucleotide polymorphisms (SNPs) and candidate genes associated with loss of equilibrium (LOE) and weight gain (WG) during high temperature challenge. We collected fin tissue from 353 individuals of largemouth bass exposed to high water temperature (37.5 °C) and performed whole-genome resequencing. Through association analysis, we successfully identified 10 SNPs and 38 candidate genes that were significantly associated with LOE, and four SNPs and 19 candidate genes that were significantly associated with WG. Using quantitative PCR and Western blot, we tested the expression of eight genes related to LOE in heat-sensitive and heat-tolerant individuals, and identified significant differences in the expression of the following five genes: Tmub2, Ngfr, Hgf, Hdac6, and Sypl. For WG, we assessed the expression of three candidate genes, among which Mrc2l displayed significant differences in expression between the high WG group and low WG group. We discuss the functions and potential biological processes of candidate genes for LOE and WG. Our results provide basic genetic information for breeding largemouth bass with high temperature tolerance.