Identification of sex-linked codominant markers and development of a rapid LAMP-based genetic sex identification method in channel catfish (Ictalurus punctatus)

Abstract

Channel catfish (Ictalurus punctatus), a commercially important aquaculture species, is native to North America and has spread worldwide. Channel catfish exhibit sexual size dimorphism, with males growing faster than females. Therefore, the creation of an all-male population is promising for growth improvement in channel catfish. In the process of monosex fish breeding, the development of sex-specific genetic markers is the most critical step. Although sex-linked SSRs and SNPs have been developed in channel catfish, they are polymorphic, unstable, and difficult to use for rapid sex genotyping. In this study, three codominant markers with large size differences between their two alleles were identified by performing a detailed comparison of the region on X and Y chromosomes that enriched male-specific SNPs using preexisting RAD-seq data and genome data. After examination by one wild and three artificially bred populations using electrophoresis on agarose gel, the accuracy rate reached 100%, suggesting that all three codominant markers could be effectively used for genetic sex identification in channel catfish. To achieve genetic sex identification performed in the field without complex equipment, a rapid LAMP-based method was established for the identification of genetic sex in channel catfish based on the codominant markers we identified. Overall, this study established rapid and effective PCR- and LAMP-based methods to identify the genetic sex of channel catfish in the laboratory and in the field.