SST基因多态性及其与牛生长性状的关联分析

Polymorphism of SST gene and its association with growth traits in cattle breeds

【目的】对秦川牛、鲁西牛、鲁西与西门塔尔杂种牛(简称鲁杂牛)、南阳牛、夏南牛和郏县红牛6个品种中国黄牛Somatostatin基因(SST)的第1外显子和第2外显子进行SNPs检测,研究其与6个品种中国黄牛部分生长性状的相关性。【方法】采用DNA直接测序技术和PCR-SSCP方法,对669头中国黄牛SST基因第1和第2外显子进行多态性分析,运用最小二乘线性模型对SST基因的不同基因型与6个品种中国黄牛生长性状进行关联性分析。【结果】在SST基因第126个碱基处找到1处多态位点,除秦川牛和鲁杂牛有GG和AG 2种基因型外,其他4个品种牛中均存在AA、AG、GG 3种基因型。运用卡方检验模型对6个品种黄牛中等位基因A/G的频率、基因型频率、多态信息含量等进行了统计分析,结果表明,各供试品种在这一位点上均处于Hardy-Weinberg平衡状态(P>0.05);该位点的A、G等位基因频率和多态信息含量在6个品种中国黄牛中分别为0.053 8～0.218 8,0.781 2～0.946 2和0.096 6～0.283 4。SST基因的多态性与6个品种黄牛的8个生长指标的相关性分析结果显示,该位点对669个个体中的某些生长性状指标具有显著影响;其中24月龄秦川牛品种中,GG型个体的体斜长、腰角宽和坐骨端宽均高于AG型个体(P<0.05);12月龄鲁西牛品种中,GG型个体的体斜长均高于AA型个体(P<0.05);12月龄鲁杂牛牛群体中,GG型个体的体斜长和体高均高于AG型个体(P<0.05);其他品种牛各基因型个体之间的生长性状指标差异均不显著。【结论】SST基因可能与秦川牛、鲁西牛和鲁杂牛的生长性状有密切的相关性,可作为秦川牛、鲁西牛和鲁杂牛生长性状的候选基因。

【Objective】 The variation of exon 1 and exon 2 of Somatostatin（SST） gene were examined and the association of this polymorphism with growth traits in Qinchuan,Nanyang,Luxi,Luxi×Simmental,Xia＇nan and Jiaxian six cattle breeds was investigated.【Method】 Using PCR-SSCP and DNA sequencing technology,669 individuals from six Chinese cattle breeds were selected to check the polymorphism of exon 1,exon 2 of SST gene.Least squares regressions analysis with linear mode was used to analyze the relationship between the genotypes and growth traits.【Result】 Mutations of G126A was detected in the exon 1 of the SST gene.The electrophoretic result showed that there were three genotypes,namely AA,AG and GG in all cattle breeds but for Qinchuan and Luxi×Simmental which had two（GG,AG） genotypes.Allelic frequencies,genotype frequencies and polymorphism information content（PIC） of this SNP were investigated and evaluated by the χ2 test in 669 cattle populations.The result showed that all cattle breeds were in Hardy-Weinberg equilibrium.Allelic frequencies of A,G and polymorphism information content of the bovine SST locus in six breeds varied from 0.053 8 to 0.218 8,0.781 2 to 0.946 2,and 0.096 6 to 0.283 4,respectively.We also obserued a potential association of this SNP with 8 growth traits indexes in 669 individuals and found significant effect on some of the growth indexes.The indexes of animals with the genotype GG were significantly higher than those of AG on bodylength,hip width and hucklebone width in 24-month-old Qinchuan cattle（P0.05）;The indexes of animals with the genotype GG were significantly higher than those of AA on bodylength in 12-month-old Luxi cattle（P0.05）;While the indexes of animals with the genotype GG were higher than those of AG on bodylength and bodyheight in 12-month-old Luxi×Simmental cattle,the indexes between genotypes were not significant（P0.05）.【Conclusion】 We conclude that polymorphisms of the SST gene is potentially associated with cattle growth traits and may be a candidate gene responsible for growth trait in Qinchuan,Luxi and Luxi×Simmental cattle.