Abstract
Fenneropenaeus chinensis is a commercially cultured shrimp in China. F. chinensis adults show significant sexual dimorphism, with larger females than males. However, sex determination (SD) of F. chinensis has not yet been elucidated. Clarification of the sex-determining system of F. chinensis could enrich our knowledge of the sex differentiation mechanism in crustaceans and facilitate the study of sex-controlling technologies. Here, we studied the sex-determining system of F. chinensis using the fixation index (FST) between the sexes to detect the genetic differentiation in resequencing data of multiple males and females. We located the candidate sex chromosome in the genome of F. chinensis and concluded the female heterogametic (ZW) SD system. We also assembled female-specific sequences, which could be used as molecular markers to identify the sex of F. chinensis. However, the differentiation of the F. chinensis Z and W chromosome is limited. RNA-seq data detected many genes with male-biased expression in the Z-specific region, which possibly could further intensify the divergency between the Z and W chromosomes.
Highlights
The evolution of chromosomes carrying the sex determination (SD) factor is an interesting form of genomic evolution (Charlesworth and Charlesworth, 2000; Bachtrog et al, 2011)
We studied the SD mechanism of F. chinensis to improve our knowledge of the sex differentiation mechanism in crustaceans and facilitate the study of sexcontrolling technologies, and provide sex-linked markers to identify the sexes at early developmental stages
The FST analysis located the sex-differentiation region on chromosome 7 (Chr7), which was regarded as the candidate sex chromosome in this study
Summary
The evolution of chromosomes carrying the sex determination (SD) factor is an interesting form of genomic evolution (Charlesworth and Charlesworth, 2000; Bachtrog et al, 2011). Selection for close linkage may promote suppressed recombination in the SD region, because the region includes a sexually antagonistic polymorphism (Bull, 1985; Bergero and Charlesworth, 2009; Wright et al, 2016). The sex-determining regions of two other Penaeus shrimps, Penaeus monodon and Penaeus japonicus, have been mapped using high-density linkage analysis (Li et al, 2003; Robinson et al, 2014), but not finemapped. The genome of F. chinensis released this year (Wang et al, 2021) makes it realizable to study the sex chromosome. We used resequencing data to detect sex-linked variants, including femalespecific sequences, and preliminarily conclude that the species had a female heterogametic (ZW) SD system
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