Identification of sex-specific DNA markers: Providing molecular evidence for the ZW sex determination system in the redclaw crayfish (Cherax quadricarinatus)

The redclaw crayfish ( Cherax quadricarinatus ) exhibit sex dimorphism, and thus, the discovery of sex-specific markers is of great significance for the study of monosexual breeding and sex-determination mechanisms in this species. In this study, sex-specific markers were found using a next-generation sequencing (NGS)-based approach. A total of 482.7 Gb clean data were obtained, which included 1,568,549,460 and 1,625,511,910 Paired-end (PE) reads from the female and male libraries, respectively. After filtering out the contigs that could be aligned to the male reads, 94 candidate W chromosome-specific contigs were identified. Among these, 12 contigs were selected and verified in different populations. Finally, five sex-specific markers were developed. Additionally, a pair of primers of Z/W-76567 was developed as a co-dominant marker. Electrophoretic analysis of the Z/W-76567 PCR product showed clear double bands for females and a single band for males. Our results provide molecular evidence for the ZW sex chromosome system in this species, which has tremendous potential for clarifying the mechanism of sex determination in C. quadricarinatus . • 94 candidate W chromosome-specific sequences were screened by the next-generation sequencing (NGS) in Cherax quadricarinatus . • 12 contigs were selected and verified, finally, five sex-specific DNA markers were obtained. • A highly specific and robust co-dominant sex-marker was developed in this species.