GENETICS CHARACTERS OF PIGS DIFFERENT BREEDS BY DNA-POLYMORPHISM OF SWINE LEUKOCYTE ANTIGEN

Abstract

Assessment of swine leukocyte antigen polymorphism (SLA–3) in different breeds pigs of Ukraine was carried out using the method of allele-specific PCR. Features of the allelic fund structure in pig breeds such as Large white, Mirgorod, Ukrainian steppe white, Ukrainian steppe speckled and Vietnamese potbellied pig were studied on four polymorphic sites: SLA–3–0602, SLA–3–0401, SLA–30101 and SLA–3–03cs01. In the study population of Mirgorod pigs, the absence of SLA–3–03cs01 and SLA–3–0602 alleles was detected. The experimental animals were polymorphic by the SLA–3–0101 and SLA–3–0401 marker systems with the above alleles frequency of 18.2 and 81.8%, respectively. By the polymorphic site SLA–3–0401 pigs of Large white, Ukrainian steppe white and Vietnamese potbellied breeds were monomorphic, whereas the representatives of the aboriginal Ukrainian steppe speckled breed the frequency of this allele did not exceed 40%. The genetic structure of Vietnamese potbellied pigs significantly differed from the characteristics obtained for the local Ukrainian breeds by four SLA sites. The most statistically significant differences are recorded for allele frequencies SLA–3–0602 and SLA–3–0101. The SLA–3–0602 allele was absent in Vietnamese potbellied breed with its 100% presence in Large white pigs. In contrast, the SLA–3–0101 allele was found in all Vietnamese pigs and was absent in a sample of the Large white pigs (p < 0.05). The distribution pattern of alleles in all of the samples selected for the study of polymorphisms in the pig locus of leukocyte antigen (SLA–3) showed a high genetic homogeneity of the Large white animals sample. The SLA–3–0101 and SLA–3–03cs01 alleles carriers were not detected, and by SLA–3–0602 and SLA–3–0401, 100% of the specimens had the respective alleles in their genotype. High values of the genetic homogeneity in these animals are confirmed by calculation of the total heterozygosity index, which was 0.136. The maximum genetic and, accordingly, genealogical relationship (according to the summary zootechnical account) were recorded in Vietnamese potbellied pigs for which the index of intragroup similarity was 0.960, and the calculated heterozygosity was the least among the breeds under study – 0.024. It is expedient to consider the results of the population-genetic characteristics analysis of the autochthonous pig breeds – the Ukrainian steppe speckled and Mirgorod when further planning selection and breeding work with them. The minimum value of intragroup similarity was found in the group of the Ukrainian steppe speckled swine – 0.156, as compared to the values of this index in pigs of other breeds under study (p < 0.05), and the theoretically calculated heterozygosity for these animals sample was 0.823. The integral assessment of breeds genetic differentiation by SLA–3 polymorphisms was obtained by performing a cluster analysis based on the calculated values of genetic distances between the breeds. The most genetically distant ones were the Mirgorod and Ukrainian steppe speckled breeds, and the value of the genetic distance between them was 0.776. In general, Ukrainian steppe speckled was characterized by the most unique distribution of SLA–3 alleles compared to other breeds under study, which has influenced the configuration of the obtained dendrogram by the UPGMA method. By means of molecular genetic, population and cluster analysis, the singularity and specificity of the Ukrainian steppe white and speckled pigs are shown. The genetic characteristics of the Mirgorod breed obtained by us can be useful in the process of recreating these animals using biotechnological methods, since the only gene pool herd of these pigs was eliminated due to the African plague infection. The generative material from the Mirgorod breed pigs has only been preserved in the Bank of Genetic Resources of the M.V.Zubets Institute of Animal Breeding and Genetics, NAAS. Determining genetic characteristics of the SLA allelic fund breed specificity of the local pig breeds reveals the prospects for using this information as an additional tool for their genetic certification, in special programs for conservation and restoration of their gene pool.