荷斯坦牛TLR2基因遗传多态性与乳腺炎抗性关系分析

Analysis of Polymorphism of TLR2 Gene and the Relationship between the Gene and Mastitis Resistance in Chinese Holstein Cattle

利用PCR-RFLP方法检测TLR2基因在297头中国荷斯坦牛中的多态性,并分析其多态性与体细胞评分(SCS)的相关性。结果表明,TLR2基因exon2扩增片断的109 bp处产生C→A的突变,并导致天冬氨酸突变为谷氨酸。TLR2基因exon2被EcoR V消化后表现多态性,表现AA,AB,BB 3种基因型,其中B等位基因为优势等位基因,等位基因频率为0.7845,而A等位基因频率则为0.2155。经χ2适合性检验,中国荷斯坦牛在该位点达到Hardy-Weinberg平衡状态。同时,群体EcoR V基因座不同基因型与SCS相关分析的结果表明,BB,AB型个体的SCS指标显著高于AA型(p<0.05),AA基因型可作为乳腺炎抗性的有利基因型,可将TLR2作为奶牛乳腺炎候选基因,将应用于分子标记辅助选择育种,为乳腺炎抗性牛群的选育奠定一定的理论基础。

In this research, polymorphisms of TLR2 gene in Chinese Holstein （n = 297）were detected with PCR- RFLP, and relationship between polymorphisms of TLR2 with somatic cell score（SCS）was analyzed. Results showed that a polymorphic site was identified,where there was a mutation C→A at position 106 bp after sequencing, which resuhed in Asp replaced by Glu. Genotype AA, AB and BB were detected by digesting the fragment with restriction endonuclease EcoR V in the population. B allele was predominant and allele frequency A and B were estimated as 0.784 5,0.215 5. χ^2 test indicated that the polymorphism locus in Chinese Holstein fitted Hardy-Weinberg equilibrium（p 〈 0.05）. In addition, the effect of the TLR2 polymorphism on SCS was analyzed. Results indicated that the SCS of BB and AB genotype cows were significantly higher than AA genotype（p 〈 0.05）. AA genotype was beneficial to mastitis resistance. We coneluded that TLR2 gene could be candidate gene of mastitis resistance for molecule marker-assisted selection breeding. This study might offer a theoretical basis on selection of the mastitis resistance in Holstein cattle.