Identification of male-specific molecular markers under the low-quality and non-chromosome-level genome revalidated the male heterogamety in bullfrog Aquarara catesbeiana

Abstract

Sex-specific molecular markers are effective tools for genetic sex identification and sex control breeding in aquaculture. Bullfrog (Aquarara catesbeiana) is a kind of aquatic animal that possesses sexual dimorphism in the prospects of growth traits like body size and age of sexual maturity. However, it is difficult to perform the process of sex identification because of the undeveloped secondary sexual characteristics at the juvenile stage of A. catesbeiana. Here, we constructed two different strategies for the detection of sex-specific markers from four mixed-pool samples using whole genome sequencing technology (WGS). Subsequently, four male-specific markers were identified and validated in another eight male frogs and eight female frogs. Moreover, the results revalidated the male heterogametic system in A. catesbeiana. These may be the first four rapid, accurate, and effective male-specific molecular markers used for genetic sex identification in bullfrogs. The results could fill the gap in research on sex-specific markers of bullfrogs and provide convenience for further research on amphibian sex determination and mono-sex breeding work. Furthermore, two detection strategies could possess the applied value in the identification of sex-specific markers in production.