| In the breeding of new varieties(strains)of high quality mutton sheep in Ningxia,one important target trait is prolificacy.Due to the heritability of reproductive traits is low,so the result of phenotypic selection effect is poor.However,molecular marker assisted selection(MAS)can improve the accuracy of selection and accelerate the breeding progress.In this study,we used the candidate gene flight mass spectrometry,choosed 60 snp sites of eight genes related to the reproductive traits of sheep as candidate sites,the polymorphism of 384 individuals of Dorper sheep(D),Small Tailed Han sheep(H),Tan sheep(T)and Small Tailed Han-Tan sheep(TH)were detected,then analyzed population differences and screened candidate genes.The results showed that:(1)Among the 9 SNP loci of the BMPR1B gene,5 loci were not polymorphic,and the genotypes were the same in 4 sheep;4 loci were polymorphic.The C gene frequency in rs418841713 loci had a significant difference between D,T and H,and TH(p<0.01),and there was a significant difference between D and T,H,and TH(0.01<p<0.05).At rs428753381 locus,T gene frequency in T group was significantly higher than D,H,and TH groups(p<0.01);at rs603752979 locus,T gene frequency was significantly higher in D than T,H,and TH groups(p<0.01);at BMPR1B746 locus,G gene frequency had a significant difference between the D,T and H,TH groups(p<0.01).(2)The 4 SNPs of the BMP 15 gene,2 SNPs of the ESR1 gene,and 7 SNPs of the PGR gene had no polymorphisms in the D,H,T,and TH4 herds,neither in genotypes.The 3 SNP loci of GnRH gene had no significant difference among these 4 groups(P>0.05).(3)Of the 15 LHR gene loci,5 SNP loci were not polymorphic and 10 loci were polymorphic,but there were no significant difference among the 4 groups(P>0.05),3 loci differed in 4 groups.At rs422326439 locus,A gene frequency is significantly higher in D group than in T and TH groups(p<0.01).At rs410734874 locus,A gene frequency was significantly higher in T and TH groups than in D and H groups(p<0.01).(4)Among the 10 SNP loci of ESR2 gene,3 were not polymorphic;7 loci were polymorphic,but the gene frequency of 4 loci did not differ significantly among the 4 groups(P>0.05);there were polymorphisms in 3 loci,at rs405617034 and rs428438934 loci,A gene frequency was significantly higher in D,H,and TH groups than in Tan sheep(P<0.01);at rs603897979 locus,T gene frequency was significantly higher in group D than in H?T?TH groups(p<0.01).(5)Among the 9 SNPs of FSHR gene,4 SNPs had very low polymorphisms and there was no difference among the 4 groups;the polymorphism at rs399253678 locus was higher,but there was no significant difference among the 4 groups(P>0.05);at rs399612350 locus,A gene frequency was significantly different between T and D,H,and TH groups(P<0.01);at rs422112895 locus,G genotype frequency had significant difference between T and H,TH,and D groups(P<0.01);at rs398233545 and rs1093458544 loci,T gene frequency had significant difference between D and T,H,and TH groups(P<0.01).(6)Two linkage groups were found on chromosome 3,the first linkage group was rs422112895 and rs398233545 loci of FSHR gene,existed TC and GT haplotypes,TC frequency was higher than GT;In the second linkage group,four loci of 422326439?398733991?421442316?and 410734874 or rs422326439?rs398733991?rs421442316?rs401906902 and rs410734874 were linked,and 5 or 6 haplotypes were formed in the LHR gene,CCAA or CCAAA had the highest frequency.One linkage group was found on chromosome 7,which was linked by two loci of 405617034 and 4284489434 of the ESR2 gene,formed two haplotypes,GT and AC,GT frequency was higher than AC.Initial identification:the 4 loci of the BMPR1B gene(rs418841713,rs428753381,rs603752979,and BMPR1B746),the rs603897979 locus of the ESR2 gene,and the 3 loci of the FSHR gene(rs399612350,rs398233545,and rs1093458544)can be used as candidate genes for the detection of multiple lambs in 4 groups. |
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