新疆褐牛基因外显子多态性及其与SCS和泌乳性状关联性分析

【目的】探索ERAP2,Cwc27,PPFIBP2,THADA,ZNF804B和AMHR2基因多态性与新疆褐牛体细胞评分及泌乳性状的相关性,旨在寻找与新疆褐牛体细胞评分及泌乳性状相关的分子标记。【方法】以新疆乌鲁木齐种牛场、新疆天山畜牧生物工程股份有限公司共169头新疆褐牛母牛为试验对象,以2008—2015年间的生产性能测定记录(包括乳脂率、乳蛋白率、总固体含量、乳糖率和体细胞计数等)和305 d产奶量为试验数据,基于课题组前期15头中国荷斯坦牛DNA混池重测序的结果筛选外显子区域10个SNPs,采用基质辅助激光电离飞行时间质谱法(sequenom mass Array genotype)分型技术验证10个SNP位点的遗传多态性,运用SAS8.1软件GLM过程对这10个SNP突变与新疆褐牛体细胞评分(SCS)、305 d产奶量、乳脂率、乳蛋白率、乳糖率和总固体的关联程度进行统计分析。【结果】10个SNP位点均具有多态性,χ~2检验表明群体中9个SNP位点符合Hardy-Weinberg平衡状态。关联分析结果表明ERAP2基因两个位点(T98741711C和G98736141A)均与新疆褐牛305 d产奶量达到极显著关联(P0.001),其中TT型和GG型个体的产奶量最高;PPFIBP2(C45667492G)位点与新疆褐牛乳糖率达到显著关联(P0.005),其中GG型个体的乳糖率最高;Cwc27(T14533269A)位点与新疆褐牛乳脂率和总固体含量达到显著关联(P0.005),与SCS达到极显著关联(P0.001),其中TT型个体的乳脂率和总固体含量均最高,AA型个体的SCS极显著高于AT和TT型;AMHR2(C26758055G)位点与新疆褐牛乳蛋白率和总固体含量达到极显著关联(P0.001),其中GG型个体显著高于CC和GC型个体。连锁不平衡分析与单倍型构建的结果发现10个SNPs构建了两个单倍型模块,其中SNP1和SNP2位点之间处于连锁不平衡状态(r20.3),SNP4和SNP10位点之间处于强连锁不平衡状态(r20.6),随后分析了单倍型与SCS和泌乳性状之间的相关性,发现单倍型与新疆褐牛SCS和泌乳性状无显著关联(P0.001)。【结论】初步发现了ERAP2,Cwc27,PPFIBP2和AMHR2与新疆褐牛SCS和泌乳性能相关,结果可为新疆褐牛产奶性状的分子标记辅助选育提供参考和依据。

Genetic Effect Analysis of SNPs from 6 Genes on SCS and Milk Production Traits in Xinjiang Brown Cattle

【Objective】The association between polymorphisms of ERAP2, Cwc27, PPFIBP2, THADA, ZNF804B and AMHR2 genes and somatic cell score (SCS) and milk production traits in Xinjiang brown cattle were studied in orderto find out molecular markers association with SCS and/or milk production traits.【Method】Taking 169 Xinjiang brown cattle cows as experimental animalsfrom Xinjiang Urumqi cattle farm and Xinjiang Tianshan Animal Husbandry and Biotechnology Co., Ltd. The experimental data including Dairy Herd Improvement records (including milk fat percentage, milk protein percentage, lactose percentage, total solid content and SCS) and milk yield of 305d, 10 SNPs were selected from exon area based on the results of DNA sequencing of 15 Chinese Holstein cows in an initial study and genotyped by Sequenom MassARRAY Genotype technology, the association between SNPs or haplotype and SCS and milk yield traits were analyzed by the least squares method in the GLM procedure of SAS8.1.【Result】The results showed that the 10 SNPs were polymorphic, and 9 SNPs were in Hardy-Weinberg equilibrium. Association analysis results showed that two SNPs in ERAP2 gene (T98741711C and G98736141A) had a highly significant association with milk yield of 305d in Xinjiang brown cattle(P＜0.001), the milk yield of TT and GG genotype was the highest in T98741711C locus and G98736141A locus, respectively; C45667492G locus in PPFIBP2 gene had a significant association with milk lactose percentage (P＜0.005), GG genotype was the highest; Cwc27 (T14533269A) had a significant association with milk fat percentage and total solid content(P＜0.005) and had a highly significant association with SCS(P＜0.001), milk fat percentage of TT genotype was the highest and SCS of AA genotype was higher than AT and TT genotypes; AMHR2 (C26758055G) had a highly significant association with milk protein percentage and total solid content(P＜0.001), GG genotype was higher than CC and GC genotypes. The results of linkage disequilibrium analysis and haplotype construction revealed that the 10 SNPs constructed two haplotype blocks, among them, SNP1 and SNP2 were in linkage disequilibrium state(0.3＜r²＜0.6), SNP4 and SNP10 in strong linkage disequilibrium state(r²＞0.6). Then the correlation between haplotype and SCS and/or milk production traits was analyzed, and the results showed that haplotype had no significant association with SCS and milk production traits(P＞0.001).【Conclusion】In this study, it was found that ERAP2, Cwc27, PPFIBP2 and AMHR2 genes had a significant association with SCS and milk production traits, and the results of the study will provide a theoretical basis and reference for the molecular marker-assisted selection in Xinjiang Brown Cattle.