中文摘要：

旨在对秦川牛DKK1基因进行SNPs检测,并研究其与秦川牛体尺、肉质性状的相关性。本研究随机选择相近饲养条件下447头18～24月龄的秦川牛母牛,采用DNA直接测序技术并结合PCR-SSCP方法进行DKK1基因全区段遗传变异检测。运用SPSS16.0程序中最小二乘法拟合线性模型对DKK1基因不同基因型与秦川牛体尺（体斜长、体高、腰高、尻长、腰角宽、胸深、胸围和坐骨端宽）和肉质性状（背膘厚、眼肌面积和肌间脂肪含量）进行关联分析。经DNA测序发现秦川牛DKK1基因存在5个突变位点,分别为第一内含子G523A突变;第二内含子A999G和A1 169G突变;第三内含子C1858T突变;第四外显子A2355G突变,其为第247位氨基酸Cys→Arg的错义突变。PCR-SSCP方法检测得到G523A和A2355G位点仅存在2种基因型;A999G、A1169G和C1858T位点存在3种基因型。卡方检验显示,G523A、A1169G和A2355G位点则处于Hardy-Weinberg极度不平衡状态（P〈0.01）,而A999G和C1858T位点于检测群体中处于Hardy-Weinberg平衡状态（P〉0.05）。关联分析表明,秦川牛DKK1基因不同突变位点的不同基因型与体斜长、体高、腰高、尻长、坐骨端宽和背膘厚、眼肌面积、肌间脂肪含量差异显著相关（P〈0.05或P〈0.01）。DKK1基因对秦川牛部分体尺、肉质性状有显著的影响,可以尝试作为秦川肉牛新品系培育的主效候选基因。

英文摘要：

The aim of the study was to research polymorphism of DKK1 gene and its association with body measurement and meat quality traits in Qinchuan cattle. 447 Qinchuan heifers from 18- to 24-month-old under similar feeding conditions were randomly selected, DNA samples were directly sequenced and the polymorphisms of DKK1 gene was analyzed by PCR-SSCP technology. Least squares fitting linear model of SPSS16.0 program were used to analyze the relationship between the different genotypes and body measurement and meat quality traits. Five SNPs had been detected in DKK1 gene including G523A in intronl, A999G and A1169G in intron2, C1858T in intron3 and A2355G in exon4,which was missense mutation with replacement of Arginine by Cystein at 247^th amino acid. The result of PCR-SSCP analysis showed that G523A and A2355G showed only two genotypes, whereas A999G, Al169G and C1858T showed three genotypes. 3（2 test showed G523A, Al169G and A2355G were not in Hardy-Weinberg equilibrium （P〈0. 01）, whereas A999G and C1858T were in Hardy-Weinberg equilibrium （P〉0.05） in Qinchuan cattle populations. Association analysis of polymorphisms of DKK1 gene with body measurement and meat quality traits showed that the genotypes of different mutations in DKK1 gene were significantly related to body length, withers height, hip height, rump length, pin bone width and backfat thickness, lion muscle area, intramuscular fatty content（P〈0.05 or P〈0.01）. It indicated that SNPs of the DKK1 gene may be closely associated with some body measurement and meat quality traits, and could be an major candidate gene for new strain breeding of Qinchuan cattle.