中国荷斯坦奶牛TBX21基因与产奶性状及体细胞数的遗传效应分析

Genetic Effects of TBX21 Gene on Milk Production Traits and SCC of Chinese Holstein Cows

为鉴定与奶牛产奶性状和乳房炎抗性相关的遗传标记,为将来的分子育种提供理论基础,以383头中国荷斯坦母牛(均为2胎牛)为研究对象,利用直接测序法及飞行时间质谱法首次寻找TBX21基因5'和3'侧翼区的SNP位点,进而对这些多态性位点与中国荷斯坦牛4个泌乳性状(305天产奶量、乳脂率、乳蛋白率、乳糖率)和体细胞数进行关联分析。结果表明:在TBX21基因5'和3'侧翼区存在2个SNP位点,一个是在3'侧翼区1091 bp处A→G的突变,一个是3'侧翼区654 bp处A→C的突变;这2个位点均处于哈代-温伯格(Hardy-Weinberg)平衡状态。关联分析结果表明,rs207725545位点AA基因型个体的4种泌乳性状和体细胞数均高于CC型个体(P>0.05);rs110420592位点GG基因型个体的产奶量和乳糖率高于AA型个体(P>0.05),AA基因型个体的乳脂率和乳蛋白率高于GG型个体(P>0.05),而GA基因型个体的体细胞数略高于其他2种基因型个体(P>0.05)。因此,在本试验群体中,TBX21基因的rs110420592和rs207725545两个位点与产奶性状和体细胞数无显著关联,后续需要扩大群体对TBX21基因的其他位点进行遗传效应分析。

In order to identify the genetic markers associated with milk production and mastitis resistance, and provide theoretical basis for molecular breeding, 383 Chinese Holstein cows（all were the 2nd parity） were chosen as study animals. Direct sequencing and time of flight mass spectrometry were used to find polymorphisms in 5＇ and 3＇-flanking region of TBX21 gene. Then association of the two polymorphic sites with the 4 milk production traits including milk yield, fat percentage, protein percentage and lactose percentage andSCC（somatic cell count） was analyzed. The results showed that two polymorphic sites were detected in 5＇ and3＇-flanking region of TBX21 gene. There were one A→G mutation at 1091 bp and one A→C mutation at654 bp in 3＇-flanking region. Both of them were in Hardy-Weinberg equilibrium. Association analysis showedthat the 4 milk production traits and somatic cell count of rs207725545 loci AA genotype were higher thanthose of CC genotype（P〉0.05）. For rs110420592, milk yield and lactose percentage of GG geno type were higher than those of AA genotype（P〉0.05）, fat percentage and protein percentage of AA genotype were higherthan those of GG genotype（P〉0.05）, and somatic cell count of GA genotype were higher than that of GG andAA genotype（P〉0.05）. The two loci of rs110420592 and rs207725545 in TBX21 gene had no significant association with the milk production traits and somatic cell count. Analysis of genetic effects on otherpolymorphic sites of TBX21 gene was needed in the future.