Identification of a candidate sex determination region and sex-specific molecular markers based on whole-genome re‑sequencing in the sea star <i>Asterias amurensis</i>

Sex determination systems are diverse in echinoderms, however, our understanding is still very limited in this research field, especially for Asteroidea species. The northern Pacific seastar, Asterias amurensis, has attracted widespread concern due to its population outbreaks and high-risk invasions. Using whole-genome re-sequencing data from 40 females and 40 males, we identified a candidate sex determination region in A. amurensis. Based on the distribution characteristics of 525 sex-associated single nucleotide polymorphisms, identified by GWAS analysis, 119 sex-specific loci were isolated combining a custom Perl script, PCA analysis, and the selection signatures of fixation index FST, suggesting that a 7-12 Mb region on chromosome 10 is a candidate sex-determining region. The existence of female-specific sequences and the genotypes of sex-specific loci indicated that A. amurensis might utilize a ZZ/ZW sex-determination system. We also developed two pairs of sex-specific primers that could distinguish the genetic sex of this starfish with 100% accuracy. As the first study on sex determination in Asteroidea, it will provide novel insights into diverse sex determination systems in echinoderms and allow for in-depth studies on sex-related eco-physiological issues in A. amurensis.