中国荷斯坦牛PIK3CB基因多态性及其与繁殖和产奶性状的关联分析

Polymorphism of PIK3CBGene and Its Association Analysis with Reproductive and Milk Production Traits in Chinese Holstein Cattle

【目的】探究磷脂酰肌醇-4,5-二磷酸3-激酶催化亚单位β(PIK3CB)基因多态性及其与中国荷斯坦牛繁殖和产奶性状的关系。【方法】通过混池测序对中国荷斯坦牛PIK3CB基因进行单核苷酸多态性(SNP)位点筛选,采用竞争性等位基因特异性PCR(KASP)技术在1 160头健康泌乳中国荷斯坦牛中进行SNP分型并进行群体遗传学分析,采用线性模型进行SNP与11个繁殖和产奶性状基于单位点和单倍型组合的关联分析。【结果】在PIK3CB基因中共检测到了17个SNPs,筛选出7个SNPs用于后续分析。关联分析发现,7个SNPs与多个目标性状存在显著或极显著的关联(P<0.05;P<0.01);位于外显子区域的g.130433743 A>G位点AA基因型个体和位于可变剪接区域的g.130448069 G>A位点GG基因型个体,其经产牛首末次配种间隔、产奶量、乳蛋白量和乳脂量最低,体细胞评分最高,上述基因型个体具有较短的首末次配种间隔,而产奶性能相对较差;g.130387717 G>A位点AA基因型个体,其初配日龄和青年牛首末次配种间隔最低,产奶量、乳蛋白量和乳脂量最高,该基因型个体的繁殖和产奶性能均较好,上述3个SNPs位点可作为中国荷斯坦牛繁殖和产奶性状的候选位点重点关注。单倍型分析发现,PIK3CB基因的g.130387717 G>A、g.130430832 A>-、g.130433743 A>G、g.130433982 C>T、g.130446073 C>T和g.130448069 G>A 6个SNPs紧密连锁形成一个单倍型块,且与多个目标性状存在显著或极显著关联(P<0.05;P<0.01),其中H2H3和H2H4单倍型组合个体的繁殖和产奶性能较好,为优势单倍型组合。【结论】中国荷斯坦牛PIK3CB基因存在丰富的遗传变异,其多态性与繁殖和产奶性状存在关联,g.130433743 A>G、g.130448069 G>A和g.130387717 G>A位点可作为潜在分子标记,为中国荷斯坦牛的平衡育种提供理论依据。

【Objective】 The aim of this study was to investigate the relationships between the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta(PIK3 CB) gene polymorphism and reproductive and milk production traits in Chinese Holstein cattle.【Method】 The single nucleotide polymorphisms(SNP) site of PIK3CB gene in Chinese Holstein cattle was screened using hybrid pool sequencing.SNP genotyping and population genetic analysis were performed in 1 160 Holstein dairy cows based on Kompetitive Allele Specific PCR(KASP) method.The linear model was employed to perform the association between SNP and 11 reproductive and milk production traits based on unit point and haplotype combinations.【Results】 A total of 17 SNPs were detected in PIK3CB gene, and 7 SNPs were screened for subsequent analysis.The association analysis revealed that a total of 7 SNPs were significantly or extremely significantly associated with various target traits(P<0.05 or P<0.01).The individuals with AA genotype at g.130433743 A>G in exon and GG genotype at g.130448069 G>A in variable splice region had the lowest mating interval, milk yield, milk protein and milk fat, and the highest somatic cell score, which suggested the individuals with the above genotypes had shorter mating intervals between the first and last mating and relatively poor milk production performance.The individuals with AA genotype at g.130387717 G>A had the lowest mating age and the lowest first to last mating interval of young cattle, and the highest milk yield, milk protein yield and milk fat.The above mentioned 3 SNPs could be considered as candidate SNPs for reproductive and milk production traits in Chinese Holstein cattle.Haplotype analysis revealed that 6 SNPs of g.130387717 G>A,g.130430832 A>-,g.130433743 A>G,g.130433982 C>T,g.130446073 C>T and g.130448069 G>A were closely linked to form a haplotype block, and were significantly or extremely significantly associated with various target traits(P<0.05 or P<0.01).Among the various haplotypes, H2 H3 and H2 H4 haplotype combinations had better reproductive and milk-producing performance, and were the advantageous haplotype combination.【Conclusion】 Polymorphism of PIK3CB gene had abundant variants which was associated with reproductive and milk production traits in Chinese Holstein cattle. g.130433743 A>G,g.130448069 G>A and g.130387717 G>A could be considered as potential molecular markers to provide the theoretical basis for balanced breeding of Chinese Holstein cattle.