RAD-Seq Mapping of Spontaneous Masculinization in XX Doubled Haploid Rainbow Trout Lines

Abstract Text: 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 unexpected 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.

Keywords:

Salmonids

Linkage map

Sex determinism