Summary: | AQUA 2018, #WeRAquaculture we are the producers and investors, the scientists and technical advisors, the legislators and educators, the students, civil society organizations and consumers of farmed aquatic products, 25-29 August 2018, Montpellier, France Turbot (Scophthalmus maximus) is a flatfish with increasing aquaculture value in Europe and China. This species shows extreme sexual growth dimorphism, females growing faster and becoming sexually mature later than males, hence the interest of industry in producing all-female populations. Sex determination (SD) of turbot shows a major genetic component, the main quantitative trait loci (QTL) being located at linkage group (LG) 5, but minor QTLs and temperature influence have also been reported. Available data suggest a ZZ/ZW system of recent evolutionary origin, since recombination is not restricted and no genetic divergence at this region is observed males and females. In this study, we carried out a GWAS analysis of SD in this species using 18,165 SNPs in a large set of 36 families. Although, previous findings were confirmed (major SD region at LG5), ~30% of families showed a different pattern suggesting association with other LGs or environmental influence. Standard SD LG5 families were used to narrow down to 531 kb the region where the master gene is putatively located. This region was deeply analyzed by re-sequencing ZZ and WW individuals to look for a diagnostic difference between sexes related to SD. Furthermore, candidate genes were scrutinized for structural differences and their expression profiles studied along the critical SD period. All data support that SD in this species meets to a complex trait with the major locus being recently recruited Peer Reviewed
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