Polymorphism Analyses Of ESR, FSHβ, PRLR Genes And Their Association With Litter Size Traits In Three Strains Of Large White Pigs

In this study,201 Large White pigs belong to three strains were used as experimental subjects:(1)The nucleotide sequence of mitochondrial D-loop region was determined in 201 Large White pigs,and the genetic polymorphism and relationship among threestrains of Large White pig were analyzed combining the 227 wild boars information from China,South Korea,Japan,Russia and Indonesia,which were downloaded from NCBI.(2)As estrogen receptor(ESR),follicle stimulating hormone(FSHβ),prolactin receptor(PRLR)gene were the three candidate genes to affect the litter size traits,use PCR amplification and direct sequencing method to detect the SNPs loci in all exons of ESR gene,exon3 of FSH gene and exon10 of PRLR gene,then analysis their correlation with litter size traits and selecte the dominant genotypes to improve litter size traits of sows.The results are as follows:(1)The results of the study on the relationship of three strains of Large White pigs: 34 polymorphic sites were detected in the D-loop region of 201 white pigs,including 7 singleton polymorphic sites and 27 parsimony information sites,and there are 19 haplotypes.The haplotype diversity and nucleotide diversity were 0.891±0.008 and 0.01198 ± 0.00034,respectively.Phylogenetic analysis showed that the population differentiation among the three strains of Large White pigs was not obvious.And it was preliminarily found that the genetic distance between Large White pigs and the pig species in north-east Asian region(such as China,Japan,South Korea and Russia)was closer.(2)The results of ESR gene study: 4 SNPs sites were found,namely,g.C669 T in exon 3,g.A1296 G in exon 6,g.C1665 T and g.A1755 G in exon 8.The TT genotype of g.C1665 T site and the AA genotype of g.A1755 G site had a significant effect on reproductive performance of female pigs(P<0.05).The haplotype combinations of H5H8,H2H5 and H5H5 were the dominant combinations of litter size traits.(3)The results of FSHβ gene study: 8 SNPs sites were found in exon 3,namely,g.A511 G,g.A617 G,g.C630 T,g.C652 T,g.C678 T,g.C735 T,g.A746 G and A921 G.The reproductive performance of sows was significantly affected byAA genotypes of g.A511 G,AA and AG genotypes of g.A617 G,CC and CT genotypes of g.C630 T,CT and TT genotypes of g.C652 T,CT and TT genotypes of g.C735 T,AA and AG genotypes of g.A746 G,AA and AG genotypes of g.A921 G and CT genotype of g.C678T(P<0.05).H2H8 haplotype combination is the dominant combination of litter size traits.(4)The results of PRLR gene study: 9 SNPs were found in exon 10,which were g.C260 G,g.C362 T,g.C527 G,g.A540 G,g.A584 G,g.A673 T,g.A745 G,g.C765 T,g.A934 G,respectively.The CC and CT genotypes of g.C362 T,AG genotype of g.A584 Gs had significant effects on reproductive performance of sows(P<0.05).The CC genotype of g.C765 T and AA genotype of g.A934 G site had highly significant effects on reproductive performance of sows(P<0.01).The haplotype combination of H2H7 and H4H4 were the dominant combinations of litter size traits.SNPs loci in ESR,FSHβ and PRLR genes and dominant genotypes that were beneficial to improve litter size traits of sows were explored in this study.The results provide a reference for screening molecular markers of sows with high reproductive performance and a theoretical basis for genetic breeding and reproductive performance testing of sows.