Infectious diseases pose significant threats to the catfish industry. Enteric septicemia of catfish (ESC) caused by Edwardsiella ictaluri is the most devastating disease for catfish aquaculture, causing huge economic losses annually. Channel catfish and blue catfish exhibit great contrast in resistance against ESC, with blue catfish being highly resistant. As such, the interspecific hybrid backcross progenies provide an ideal system for the analysis of resistance QTL. In this study, we conducted GWAS analysis to locate genomic regions associated with ESC resistance by selectively genotyping the first generation backcross progenies with the catfish 690K SNP arrays. Two genomic regions on linkage group (LG) 1 and LG23 were determined to be significantly associated with ESC resistance as revealed by a mixed linear model and family-based association test. A number of genes within QTL have known functions in immunity, making them potential candidates as disease resistance genes. For instance, seven genes on LG1 (nck1, agtr1, trpc1, abi1, apbb1ip, actr3b, and vav3) and three genes on LG23 (mrc1l, prkcq, and gata3) were involved in immune-related functions. These genes mainly function in signaling pathways of phagocytosis and T-cell activation, suggesting their roles in disease resistance. This study demonstrated the power of GWAS analysis for the identification of QTL in the hybrid system. We previously reported one QTL in LG1 using third generation backcross progenies, which was validated here in the first generation backcrosses, suggesting that this QTL is operating in various populations of a broad genetic background, making it useful for application in marker-assisted selection.
About the Presenter
Suxu Tan is a PhD student at Auburn University. Before coming to the United States as a graduate student, he graduated from China Agricultural University and went to the graduate school at Ocean University of China. Currently, his main project is to uncover the QTL controlling ESC disease resistance in catfish using genome-wide association study.