Genome-Wide Association Study and target resequencing in racing Quarter Horses

Abstract

Different selection objectives within the Quarter Horse breed led to the formation of groups with distinct skills, including the racing line. With a smaller population size in Brazil, but of great economic representativeness, the racing line show a better performance in short-distance races than any other line or breed, and are the fastest horses and one of the fastest animals in the world. The Quarter Horse can reach a speed of up to 88 km/h and can sprint the quarter mile (approximately 402 m) from a standing position in less than 21 seconds. Although the athletic performance of horses is probably influenced by a large number of genes, as in humans, few genetic variants have so far been related to this trait and this was done exclusively in Thoroughbreds. In view of that the effects of DNA polymorphisms on characteristics are intrinsic parameters of each line or breed in a given environment and considering the lack of information regarding the potential of use of marker-assisted selection in horses, especially in the Quarter Horse, breed of great importance in the world and also in Brazil, the objectives of the present study will be: 1) conduct comprehensive genome-wide association study (GWAS) with performance characteristic in Quarter Horses of the racing line using equines high-density SNP genotyping arrays; 2) sequencing genomic regions of interest, significantly associated at GWAS, in order to prospect for genetic polymorphisms direct responsible (causal)or in strong linkage disequilibrium with racing performance. For this, genotypic and phenotypic information from 356 Quarter Horses of the racing line, of both sexes and registered in breed association, will be used. (AU)