Polymorphisms in the Promoter Region of Swine BMP7 Gene and Their Association with Reproductive Traits
|School||Henan Agricultural University|
|Course||Animal Genetic Breeding and Reproduction|
|Keywords||pig BMP7 promoter polymorphism reproductive traits|
Bone morphogenetic protein 7 is a member of the family of bone morphogenetic proteins. The multifunctional protein also plays an important role in formation of bone and cartilage, and is also involved in the regulation of mammalian reproduction. No reports on the genetic diversity analysis have been found so far in the studies of porcine BMP7 gene, thus the present study took this gene as a target gene for the pig reproductive traits. First, a DNA pool was build using DNA samples from 100 sows of different breeds, and sequenced to screen the putative SNPs occurred in the promoter region. Then after, the PCR-RFLP was employed to genotype the total 255 sows and gilts including 26 Landrace, 147 Largewhite, 82 Doroc at the 4 loci (T-3722C, A-3684G, C-3522G, A-1027G). The main results are as follows:(1) A total 39 polymorphic loci, including of 3 deletes and 36 signal nucleotide polymorphisms, were pick out for the first time in the studies of this gene.(2) The genotyping for the 4 variations found reveled that each of these loci occurred in the population studied with the full 3 genotypes. Of 4 sites, T-3722C was dominated by the allele T and genotype TC, with an allele frequency and genotype frequency of 0.67 and 0.48, respectively. The further examination showed that this locus coincided with the Hardy-Weinberg equilibrium, with a polymorphic information content(PIC) ,heterozygosity (He)and effective allele number(Ne) of 0.34,0.44 and 1.80 in the population of interest, respectively. At the locus A-3684G, the dominated allele and genotype were G (0.84) and GG (0.76), respectively. Whereas, this locus was not in the balance of Hardy-Weinberg, and PIC, He and Ne were 0.23, 0.27 and 1.36, respectively. For another locus C-3522G, the dominances were C and CG, with the frequencies of 0.71 and 0.48, respectively. The locus C-3522G was also not consistent to the Hardy-Weinberg equilibrium, and the PIC was 0.33, the He 0.41 and Ne 1.70. At the fourth locus A-1027G, the allele A was dominant to G, while the AA was dominant to the remaining genotypes. The frequencies of A and AA were 0.81 and 0.67, respectively. As the immediate 2 loci, the locus A-1027G did not meet the balance of Hardy-Weinberg, and PIC, He and Ne were 0.26, 0.31 and 1.44, respectively.(3) The subsequent association analysis of these 4 loci with the corresponding reproductive traits demonstrated that the locus A-3684G was absolutely unrelated to the all characters examined. However, the SNP T-3722C showed significant correlation with some traits, such as the live litter size and litter weight at birth, as well litter weight at the weaning of 21 day of homozygote TT and heterozygote TC were higher than those of homozygote CC, respectively. For the locus C-3522G, the homozygote CC and heterozygote CG were lower than homozygote GG in the weaning litter weight. For the locus A-1027G, the homozygote AA and heterozygote AG were found super than homozygote GG in the live birth litter size and birth litter weigh. The bioinformatics analysis employed tfsearch and the other online program for transcriptional factors demonstrated that the 3 SNP sites highly related to the reproductive traits were all in or closely near the putative transcriptional factor binding sites located in the promoter region, while the remaining SNP unrelated to the phenotypes was located beyond any predicted TF binding sites.Therefore, it can be reasonably concluded as follows:(1)Swine BMP7 gene promoter region polymorphism was screened and found 39 sites.(2) The promoter region of porcine BMP7 is rich in the genetic variations, implying a great role in the regulation of this gene as well as the phenotypes related to the reproduction.(3) Though the further assertion is needed, the loci T-3722C, C-3522G and A-1027G may affect the reproductive traits of sows by modulating the transcription activity of swine BMP7. These polymorphism sites can be expected to develop possible molecular markers for the selection of corresponding traits in the swine breeding.