Genome-wide association analysis study on host resistance against the Aeromonas veronii of largemouth bass Micropterus salmoides.

Largemouth bass (Micropterus salmoides) has become one of the most important freshwater economic fish farmed almost all over China in recent years. At the same time, the increasing outbreaks of diseases in its aquaculture process have caused substantial economic losses to this industry. However, at present, the genetic basis of disease resistance, including resistance against Aeromonas veronii infection, in largemouth bass is very limited. Therefore, a genome-wide association study (GWAS) on host resistance against the A. veronii of largemouth bass was conducted in the present study. A total of 627 largemouth bass were artificially challenged by A. veronii, among which 160 of the earliest deaths and 173 of the final survivals were genotyped. A total of 3076 high-quality SNPs were used for further analysis employing two analysis models, of which six shared SNPs were finally identified as significant molecular markers with the explaining phenotypic variance ranging from 2.28 % to 8.95 %. Furthermore, seven candidate genes were identified, including one gene, T-cell surface antigen CD2, which is directly involved in T cell activation and the cellular immune response. Additionally, the other identified genes play roles in critical processes such as cell survival, inflammatory responses, and signal transduction. This study lays a genetic foundation for research on largemouth bass disease resistance and studies related to A. veronii. It also contributes significantly to the future development of the commercial production of largemouth bass.