Work

Uncovering a sex determination region and female-specific markers in the Crown-of-thorns starfish

Year: 2026

Type: preprint

Abstract: Population outbreaks of Crown-of-thorns starfish (COTS) in the Indo-Pacific region have inflicted devastating damage on coral reef ecosystems. Manual culling remains the most effective control method against this marine pest, but it entails substantial labor and economic costs. Emerging research focused on the COTS biology, including molecular biology, has provided foundational insights that may support the development of new approaches to mitigate future population outbreaks. However, limited understanding of its sex determination mechanism and the absence of non-invasive sex identification methods have impeded sex-related research and the development of effective biocontrol strategies. Therefore, we performed high-coverage whole-genome re-sequencing of 30 COTS females and 30 COTS males to identify candidate sex determination regions, and developed sex-specific molecular markers. The distribution of sex-associated SNPs and sex-specific SNPs, along with the selection signatures of fixation index indicated that a 11–14 Mb physical region within COTS chromosome 10 was a candidate sex determination region. Within this region, the PKNOX2 gene, harboring numerous sex-associated SNPs and showing testis-biased expression, might influence sexual dimorphism. We successfully developed two pairs of female-specific molecular markers, which were validated in separate populations with 100% accuracy, enabling the non-invasive identification of the genetic sex in COTS. In addition, the identification of female-specific sequences and the genotypes of sex-specific SNPs suggested COTS might possess a ZZ/ZW sex determination system. Our study not only provides novel insights into the diverse sex determination mechanisms in echinoderms, but also establishes a genetic foundation for sex-related physiological research and the future development of biocontrol strategies against COTS.

Source: Research Square

DOI: 10.21203/rs.3.rs-9754053/v1