Implications of genome-wide single nucleotide polymorphisms in jade perch (Scortum barcoo) reveals the putative XX/XY sex-determination system, facilitating a new chapter of sex control in aquaculture

Jade perch (Scortum barcoo) is a new teleost in the developing aquaculture freshwater finfish grow-out sector in Australia and China. However, key information on the breeding sex determination system (SDS) remains poorly understood, hampering sex control programs and genetic improvement. In this study, the jade perch SDS was examined by investigating genome-wide single-nucleotide polymorphisms (SNPs) using diversity arrays technology and cytogenetics analysis to identify the genomic variants associated with sex-linked regions. Although the cytogenetic results showed no variation in the chromosomal patterns between males and females, one male-specific locus and 13 male-linked loci were observed, suggesting that jade perch exhibits male heterogametic XX/XY SDS. Male-specific loci on the putative Y sex chromosome were also identified as an extremely small proportion of the genome. A homology search of the SNP loci revealed the male-specific loci were homologous to the Gypsy transposable element. This might be a remnant of an initial accumulation of repeats on the Y chromosome at the early stage of sex chromosome differentiation. The results provide a base for sex control breeding biotechnologies and genetic improvements to promote sexual size dimorphism and other new approaches to improve the commercial value of jade perch.