绵羊LHCGR基因多态性与产羔数的关联分析

Polymorphism of LHCGR Gene and Its Association with Litter Size in Sheep

实验旨在探究绵羊LHCGR基因g.75709226G>T、g.75733123G>A、g.75737425T>C、g.75728068G>T位点多态性与绵羊产羔数之间的关系,以期为绵羊高繁殖力分子育种提供新的遗传标记。利用全基因组重测序结合Sequenom MassARRAY誖SNP技术对3个多羔绵羊品种(小尾寒羊、湖羊和策勒黑羊)和4个单羔绵羊品种(滩羊、萨福克羊、苏尼特羊和草原型藏羊)共768只绵羊LHCGR基因g.75709226G>T、g.75733123G>A、g.75737425T>C、g.75728068G>T位点的多态性开展检测,并与小尾寒羊产羔数进行关联分析。结果表明:LHCGR基因g.75709226G>T位点存在GG、GT、TT三种基因型,g.75733123G>A位点存在GG、GA、AA三种基因型,g.75737425T>C位点存在TT、TC、CC三种基因型,g.75728068G>T位点存在GG、GT、TT三种基因型,g.75709226G>T、g.75733123G>A位点的基因型频率和等位基因频率在单、多羔品种间均达到了差异极显著水平(P<0.01),g.75728068G>T位点的等位基因频率在单、多羔品种间达到了差异显著水平(P<0.05)。群体遗传学分析表明,g.75709226G>T位点在小尾寒羊、草原型藏羊、策勒黑羊、湖羊和滩羊中均表现为低度多态(PIC<0.25),在萨福克羊和苏尼特羊中表现为中度多态(0.25<PIC<0.5);g.75733123G>A位点在7个绵羊品种中均表现为低度多态;g.75737425T>C位点在7个绵羊品种中均表现为中度多态;g.75728068G>T位点在草原型藏羊中表现为低度多态,在其余品种中表现为中度多态。卡方适合性检验表明,g.75709226G>T、g.75733123G>A和g.75737425T>C三个位点在7个绵羊品种中均处于哈代-温伯格平衡状态(P>0.05);g.75728068G>T位点在苏尼特羊和滩羊中处于哈代-温伯格平衡状态(P>0.05),在其余5种绵羊中处于哈代-温伯格不平衡状态(P<0.05)。关联分析表明,g.75709226G>T位点多态性与小尾寒羊第1胎产羔数有显著关联(P<0.05),且前3胎中TT个体和GT个体产羔数均高于GG个体;g.75733123G>A位点多态性与小尾寒羊第1胎产羔数有显著关联,且前3胎中GA个体和GG个体产羔数均明显高于AA个体;g.75737425T>C、g.75728068G>T位点多态性与绵羊第1、2、3产羔数均无显著关联(P>0.05)。综上所述,LHCGR基因g.75709226G>T、g.75733123G>A位点可以作为小尾寒羊产羔性状选育的潜在分子标记,g.75737425T>C、g.75728068G>T两个位点不适合用于小尾寒羊产羔性状的选育。

The aim of the present study was to elucidate association between the polymorphism of LHCGR gene(g.75709226 G>T,g.75733123 G>A,g.75737425 T>C,g.75728068 G>T) and litter size in sheep,providing new genetic markers for high prolific molecular breeding of sheep.Polytocous(Small Tail Han sheep,Hu sheep,Cele Black sheep)and monotocous(Tan sheep,Suffolk sheep,Sunite sheep,Prairie Tibetan sheep)sheep breeds were selected and Sequenom Mass ARRAYSNP assay was applied to detect the genotypes of g.75709226 G>T,g.75733123 G>A,g.75737425 T>C and g.75728068 G>T loci of LHCGR gene,then the association between the loci and the litter size in Small Tail Han sheep was analyzed.The results showed that three genotypes were found at g.75709226 G>T(GG,GT,TT),g.75733123 G>A(GG,GA,AA),g.75737425 T>C(TT,TC,CC),g.75728068 G>T(GG,GT,TT) in both polytocous and monotocous sheep. The genotype frequency and gene frequency of g. 75709226 G>T,g.75733123 G>A loci of LHCGR gene were extremely significantly different between polytocous and monotocous sheep(P<0.01),and the gene frequency of g.75728068 G>T locus was significantly different between polytocous and monotocous sheep.Population genetic analysis showed that the g.75709226 G>T was at low polymorphism in Small Tail Han sheep,Prairie Tibetan sheep,Cele Black sheep,Hu sheep and Tan sheep(PIC<0.25),it was at moderate polymorphism in Suffolk sheep and Sunite sheep(0.25<PIC<0.5).The g.75733123 G>A locus was at low polymorphism in 7 sheep breeds.The g.75737425 T>C locus was at moderate polymorphism in 7 sheep breeds.The g.75728068 G>T locus was at low polymorphism in Prairie Tibetan sheep,it was at moderate polymorphism in other breeds.The χ2 test indicated that the g.75709226 G>T,g.75733123 G>A and g.75737425 T>C loci of 7 breeds were in Hardy-Weinberg equilibrium(P >0.05).The g.75728068 G>T locus of Sunite sheep and Tan sheep was in Hardy-Weinberg equilibrium(P >0.05),it was not in Hardy-Weinberg equilibrium in other breeds(P<0.05).The association analysis indicated that the polymorphism of the g.75709226 G>T locus had correlation with the first litter size of Small Tail Han sheep,while the litter size of TT and GT was higher than GG in the first three births.The g.75733123 G>A locus had correlation with the first litter size of Small Tail Han sheep,while the litter size of GA and GG was higher than AA in the first three births.The g.75737425 T>C and g.75728068 G>T loci had no correlation with the litter size of first,second or third parity Small Tail Han sheep(P >0.05). Therefore,it could be concluded that the g.75709226 G>T and g.75733123 G>A loci of LHCGR gene might be potential molecular markers for breeding of Small Tail Han sheep,the g.75737425 T>C and g.75728068 G>T loci might not be suitable for breeding of Small Tail Han sheep.