| Studying the genetic structure and genetic variation of cattle population is the base of protecting and utilizing the breed resource of cattle, and the precondition of breeding and improving. But performance traits of beef cattle are the quantitative traits which are controlled by multiple genes. The genetic progress is slower and inaccuracy in the animal phenotype selection. Genetic markers can be included into marker-assisted selection programs to select at early stage and increase selecting accuracy. With the development of molecular genetic techniques, quantitative genetics and computer simulation methods, a large numbers of genetic markers can be obtained and it also supplies possibility to study their association with QTL. One of the genetic markers, microsatellite DNA takes on the strong foreground of application. This study is relating to preliminary study on genetic variation of microsatellite DNA in beef cattle population and their association with beef performance traits.Five cattle breeds/cross, including Yanbian yellow cattle, Limousin, Charolais, LimousinxYanbian and CharolaisxYanbian, were used as experimental population. The techniques of PCR-SSLP and method of electrophoresis on polyacrylamide gels were used to analyze the genetic structure and genetic variation of five microsatellite loci in five breeds/cross. The clustering dendrogram from standard genetic distance of the five microsatellite polymorphisms is analyzed, The five microsatellites used in this study have all been sequenced, and their sequences are analyzed. The performance traits including the regulation of beef cattle linear valuation were measured, and the association between genetic markers and performance traits were analyzed by using general linear model (GLM). The results were as follows:1. Five microsatellite loci ETH10, IDVGA46, IDVGA44, ETH225 and BM2113 were used to analyze the genetic structure and genetic variation in five breeds/cross. The polymorphism information content (PIC) values are 0.43016, 0.36482, 0.53231, 0.58535 and 0.61386 for Yanbian yellow cattle, 0.64475, 0.65003, 0.63067,0.42785 and 0.55469 for Limousin, 0.37500, 0.59259, 0.44963, 0.44963 and0.37500 for Charolais, 0.28906, 0.19784, 0.53038, 0.69915 and 0.53072 for LimousinxYanbian, 0.57518, 0.19784, 0.77480, 0.65841 and 0.54334 for CharolaisxYanbian, respectively. Heterozygosity and effective number of alleles range from 0.2094 to 0.8015, from 1.2649 to 5.0378, respectively. By using neighbor-joinning method (NJ), the clustering dendrogram from general genetic distance of the five microsatellites can correctly reflect geographical distribution of the five cattle population and the relationship among its. The mean of allele, the average polymorphism information content, the average effective numbers of alleles and the average gene heterozygosity for per microsatellite locus in every population were calculated, the values for Yanbian cattle are 5.80, 0.51, 2.33 and 0.56, respectively, and Yanbian cattle shows high polymorphism. The results show that the average PIC and the average gene heterozygosity hi Limousin were the greatest, and the values are 0.58 and 0.63, respectively, but its in population of Limousin crossed with Yanbian cattle are the lowest, and the values are 0.45 and 0.48, respectively.2. The five microsatellites used in ths study have all been sequenced. Results show that four of them, ETH10, IDVGA46, IDVGA44 and BM2113 are perfect (GT/CA)n microsatellite, while ETH225 is imperfect (TG)4(CG)(CA)15 microsatellite. The homology between 5 microsatellites sequenced in this study and the corresponding microsatellite loci published in NCBI (National Center for Biotechnology Information) are all above 96%.3. The performance traits including the regulation of beef cattle linear valuation were measured, and the association between genetic markers and performance traits were analyzed by using general linear model (GLM). Three microsatellite loci, ETH10 , IDVGA46 and BM2113 were associated to bee...
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