本土绵羊品种GH与IGF-1基因多态性分析

Polymorphism Analysis of GH and IGF-1 Genes in Native Sheep Breedsroke

生长性状是绵羊育种中关注的重要性状。GH和IGF-1基因已被证明是影响动物生长发育的重要候选基因。因此,了解中国本土绵羊GH和IGF-1基因的遗传多样性,将为提高本土绵羊的生产效率、制定遗传育种和品种改良措施奠定基础。本研究以本土绵羊品种呼伦贝尔羊、藏羊、湖羊、阿勒泰羊、小尾寒羊和滩羊为主要研究对象,以澳白羊为参考,通过Sanger测序检测了340只绵羊GH和IGF-1外显子单核苷酸多态性。研究发现,GH和IGF-1基因外显子区分别检测到11个和3个SNPs,呈品种特异性分布,在群体中处于低度至中度多态。连锁不平衡分析发现,GH基因的SNP1、SNP3、SNP6、SNP7和SNP8呈强连锁不平衡,构建的7种单倍型中,CGACAG是优势单倍型(52.6%),而IGF-1基因的3个SNPs之间连锁关系很弱。生物信息学分析发现,检测到的14个SNPs中GH的SNP2、SNP4、SNP8和IGF-1的SNP1、SNP3为新发现的多态位点,其中SNP4和SNP9为错义突变,可能会导致编码蛋白质二级结构与三级结构发生改变。研究结果表明,与其他本土品种和澳白羊相比,湖羊的GH和IGF-1基因具有较为丰富的遗传变异。已有研究证实GH的SNP6和SNP9以及IGF-1的SNP2不同基因型与绵羊的生长和胴体性状相关联,且在本土品种中均有多态,推测GH基因的SNP6、SNP9和IGF-1基因的SNP2可作为本土绵羊生长性状分子标记辅助选择的候选SNPs。

Growth traits are the important traits concerned in sheep breeding.GH and IGF-1 genes are well-accepted candidate genes that affect animal growth and development.Understanding polymorphisms of GH and IGF-1 genes lays the foundation to design the breeding strategy and to improve the productive efficiency for local sheep breeds.In the present study,340 sheep breeds including 6 native breeds,Hulunbuir sheep,Tibetan sheep,Hu sheep,Altay sheep,small tail Han sheep and Tan sheep,as well as Australian white sheep,which to be taken as reference were chosen to assess polymorphisms of exons in GH and IGF-1 genes by using Sanger sequencing.We identified 11 SNPs and 3 SNPs in exons of GH and IGF-1 genes respectively.The identified SNPs were of a variety-specific distribution with low to moderate polymorphism in the population.The strong linkage disequilibrium was observed in SNP1,SNP3,SNP6,SNP7 and SNP8 of GH gene,which constructed 7 haplotypes and CGACAG was the dominant one(52.6%).In IGF-1,3 SNPs showed weak linkage.Bioinformatics analysis found that,SNP2,SNP4 and SNP8 in GH as well as SNP1 and SNP3 in IGF-1 were newly discovered mutation among the 14 SNPs.We found SNP4 and SNP9 of GH were missense mutations,which probably led to variations in secondary and tertiary structures of the encoded protein.Conclusively,GH and IGF-1 genes of Hu sheep showed higher genetic polymorphism than that in other domestic breeds and Australian white sheep.According to the associations between different genotypes and growth traits as well as the polymorphisms of SNPs in previous studies,we inferred the potential application of SNP6 and SNP9 in GH gene and SNP2 in IGF-1 gene as candidate SNPs for growth traits molecular marker-assisted selection in endemic sheep breeds.