Sex-specific markers developed by genome-wide 2b-RAD sequencing confirm an XX/XY sex determination system in Chinese longsnout catfish (Leiocassis longirostris)

Abstract

Longsnout catfish (Leiocassis longirostris), an important commercial fish in China, shows significant sexual size dimorphism. However, the sex determination system and mechanism of longsnout catfish remain unknown. In this study, an effective protocol of artificial gynogenesis using heterologous sperm was successfully developed and male heterogametic XX/XY sex determination system was revealed in longsnout catfish. Subsequently, sex-specific markers were developed based on isolated homologous X-specific and Y-specific sequences by 2b-RAD sequencing and PCR amplification. Finally, the Y-specific and XY-shared primers were developed and validated in a full-sib family, a gynogenetic population and two local populations, which further verify the sex determination system. Therefore, this study not only reveals XX/XY sex determination system in longsnout catfish, but also provides applicable sex-specific markers for production of all-male population for aquaculture in the future.