A Genome Scan of a Four-Way Tilapia Cross Supports the Existence of a Quantitative Trait Locus for Cold Tolerance on Linkage Group 23

Summary

A genome scan, searching for Quantitative Trait Loci (QTL) for the traits cold tolerance and body weight in tilapia, was performed on a cross between an (Oreochromis niloticus x Sarotherodon galilaeus) male and an (O. mossambicus x O. aureus) female. 54 microsatellites and 23 AFLP primer combinationswere genotyped and tested for marker-trait associations. Sex-specific linkage maps were constructed from this data. 23 point-wise significant marker-trait associations were found in the genome scan, and putative QTLs were subsequently tested inanother (On x Sg) x (Om x Oa) family. None of the putative QTLs from the first experiment were significant in the secondexperiment. However, one microsatellite, UNH130, found to beassociated to weight in the first experiment, was found to be strongly associated to cold tolerance in the second experiment. Since QTLs for cold tolerance and body weight were recentlyfound on the linkage group containing UNH130 (linkage group 23) in another study, this linkage group was investigated more closely using interval mapping. Evidence was found for the cold tolerance QTL segregating in the female parent as well.