RAD-seq mapping of spontaneous masculinization in XX doubled haploid rainbow trout lines

Sex in rainbow trout is primarily determined by a genetic male heterogametic system encoded by a master sex-determining gene sdY. However, the occurrence of spontaneous phenotypic males in all-female doubled haploid (DH) gynogenetic populations suggested that multiple sex-influencing loci could exist in trout as found in other species (tilapia, common carp, Atlantic salmon, zebrafish). In order to get further insight in the genetic determinism of this un-expected masculinization, we crossed a DH XX spontaneously sex-reversed male with a normal female. Two F1 females were then reproduced by mitogynogenesis and their DH progeny (n=168) were genotyped using RAD sequencing. A genome scan of 9500 markers was obtained resulting in a linkage map of 2860 cM. Several putative QTL regions have been identified suggesting that more than one mutation could be involved in the observed deviation from the strict XX/XY sex determinism system