Study of polymorphism of the ASIP and MC1R genes in Arabian horses

Abstract

Coat colour is one of the most variable morphological traits in domesticated horses and an important character of any breed. The purebred Arabian is the most ancient cultural breed of horses. The breed is characterized by presence of only four coat colours: gray, bay, chestnut and black. The black coat colour is extremely rare in the Arabian breed, so traditionally purebred black Arabian horses are very much valued by breeders. A horse of a rare coat colour always attracts more attention of buyers. It is known that two genes, MC1R and ASIP, encoding melanocortin-1 receptor and agouti signaling protein, respectively, play a key role in variation of coat colours in mammals. The aim of the study was to investigate polymorphism of the ASIP and MC1R genes in purebred Arabian horses bred in Russia. The number of genotyped purebred Arabian horses was 80. It was found that the frequencies of the dominant “A” allele at the ASIP locus and the dominant “E” allele at the MC1R locus were 0.900 and 0.256, respectively. The most common genotypes in the studied population were “eeAA” (43.75%) and “EeAA” (31.25%). The rarity of the black coat colour in the studied population was due to the high frequency of the dominant allele “A” at the ASIP locus, which limits the synthesis of black pigment and determines the bay colour. The pedigree analysis of the genotyped horses revealed differences between male lines in the frequency of alleles at the ASIP and MC1R loci. The alleles that determine the black coat colour had more higher frequencies in the male lines of Koheilan I and Amurath.