Screening and characterization of sex-linked DNA markers and marker-assisted selection in the Southern catfish (Silurus meridionalis)

The Southern catfish (Silurus meridionalis), which exhibits a sexual dimorphism with female growth faster than male, is an economically important fish in China. However, the lack of a rapid and accurate sex specific marker has hampered the application of sex control in the breeding process, as well as the investigations of sex-determination in this species. In this study, by comparative analysis of next generation sequencing (NGS) and re-sequencing data from male and female samples, 38 candidate Y chromosome-specific sequences were screened out, their sex-specificity were validated in Southern catfish through PCR amplification. Finally, 8 sex-linked DNA markers were obtained to distinguish the genetic sex of Southern catfish. Importantly, one of those markers (Marker-8) could serve as a highly specific and robust co-dominant marker for genetic sex identification of XX, XY and YY individuals. Subsequently, a marker-assisted selection (MAS) technique was developed for the mass production of XX all-females for aquaculture and YY supermales for basic research especially in sex determination. In conclusion, our current data suggest an XY sex determination system in the Southern catfish. Sex-linked DNA markers obtained in this study will have potential applications in the isolation of sex determine gene, elucidation of the sex determination mechanism, and accelerate the development of sex control breeding in Southern catfish.