POLYMORPHISM OF MEF2B GENE TRANSCRIPTION FACTOR IN RUSSIAN MERINO SHEEP BREEDS

Abstract

Studying the polymorphism of productivity candidate genes is the key to the
development of marker-associated selective sheep breeding. Special attention is paid to
selection which increases the indicators of meat productivity and the study of polymorphism
of genes that control the growth and development of muscle tissue. The transcription factor
gene MEF2B is a positive regulator of myogenesis. MEF2B protein product controls the
transcription of muscle-specific genes including the marker gene of meat productivity –
myostatin. The aim of our study was to analyze the frequency of alleles and genotypes
occurrence by 4 SNP markers in MEF2B gene in Merino sheep breeds. The study was
conducted on the basis of All-Russian Research Institute of Sheep and Goat Breeding –
branch of the FSBSI "North Caucasus FARC" and FSBEI of Higher Education "Stavropol
State Agrarian University". The objects of the study were one-year-old rams of Jalgin Merino
(JM, n = 20), Manych Merino (MM, n = 20), and Soviet Merino (SM, n = 20) breeds from the
breeding farms of the Stavropol Territory. Based on the results of the targeted sequencing of
MEF2B gene, the frequencies of alleles and genotypes occurrence were determined by the
substitutions rs420767326, rs413905991, rs401426310, and rs417014745. The rs401426310
substitution was the most common in sheep of all the studied breeds. The average frequency
of occurrence of the mutant A allele was 81.7 %. The average frequency of occurrence of the
mutant allele A of rs420767326 substitution was 38 %, and the mutant allele T of
rs413905991 polymorphism was 7.5 %. The rs417014745 substitution is rare. It was
identified only in the heterozygous state and only in one representative of the JM breed. This
substitution was not found in rams of SM and MM breeds. There was found a deviation of the
distribution of genotype frequencies from the Hardy-Weinberg equilibrium of rs420767326
and rs401426310 polymorphisms, which can be related to selection pressure and the selection
advantage of prevailing genotypes carriers. It is advisable to concentrate the further studies on
the correlation of single nucleotide substitutions rs420767326, rs401426310 with indicators of
meat productivity.