A Study On The Polymorphism Of MHC-DRB Genes And Their Relatedness To The Antler Productivity In Sika Deer (Cervus Nippon)

Antler is the major product of the deer farming. High productivity of antler is one of important economic traits for the selection of male breeders. So the breeding of deer focuses on the steady improvement of the productivity. Routine breeding of sika deer is too consuming in time and low in efficiency, as well as requiring a large basic breeding population. Molecular marker aid breeding can ideally overcome these defects, but there has to be numerous genetic markers available. However, up to date, there was no genetic marker that is related to the trait of antler growth in sika deer available in either domestic or abroad.The major histocompatibility complex (MHC) gene is reported closely related to the development of secondary sexual characters of animals. The technique of PCR-SSCP was used in this paper to study the polymorphisms of exon 2 of MHC-DRB gene in sika deer, and probe the relatedness of the gene to antler productivity. The results showed: (1) 16 alleles of the second exon of MHC-DRB gene were found in captive sika deer population, which were named allele A3, A2, A1, A, B, D, C, C1, E, F, Q H, I, K, J1 and J, and the frequency of the alleles was 0.5660, 0.6604, 0.6604, 0.6038, 0.4151, 0.2453, 0.4528, 0.2642, 0.3962, 0.6792, 0.6981, 0.6792, 0.7925, 0.5849, 0.2830 and 1.0000 respectively. (2) The heterozygosity of the second exon of MHC-DRB gene was disequilibrium in captive sika deer population, high in some individuals and low in the other. (3) 38 haplotypes of the second exon of MHC-DRB gene were found in 43 sika deer individuals, suggesting a high polymorphism of MHC-DRB gene in this population. (4) The correlation between heterozygosity of the second exon of the MHC-DRB gene and antler productivity of sika deer was found significantly positive, with a correlation coefficient 0.532 (P<0.01). (5) Nine alleles of the second exon of MHC-DRB gene that are significantly positively correlated to the antler productivity were discovered, namely allele A, E, F, B, C, G, H, I and K. Their correlation coefficients were 0.311(P<0.05), 0.334(P<0.05), 0.372(P<0.05), 0.473(P<0.01), 0.471(P<0.01), 0.405(P<0.01), 0.461(P<0.01), 0.452(P<0.01) and 0.442(P<0.01) respectively. (6) Among these 9 alleles, allele A, B and C were found existing only in the group of extremely high productivity, not existing in the group of extremely low productivity. It suggests that these 3 alleles could be candidate genetic markers for early identify of antler productivity in sika deer.The results mentioned above indicated that scoring the antler productivity of sika deer with the heterozygosity of the second exon of MHC-DRB gene was feasible; MHC-DRB gene is deserved to be the genetic marker for early identify of antler productivity in sika deer, predicting a wide application perspective.