柯乐猪BMP7基因SNP位点与繁殖性能的关联分析

Association analysis of BMP7 gene SNP loci with reproductive performance in Kele pig

【目的】明确骨形态发生蛋白7基因(BMP7)单核苷酸多态性(SNP)位点与柯乐猪繁殖性能的关联性,挖掘柯乐猪繁殖性状的分子辅助标记,为加速柯乐猪繁殖性能提升及推进其品种改良进程提供技术支撑。【方法】选取150头健康经产柯乐母猪为研究对象,采用Sanger测序法筛查鉴定BMP7基因SNP位点,计算各SNP位点的群体遗传参数,并通过SPSS 22.0中的一般线性模型(GLM)分析SNP位点与柯乐猪总产仔数、初生窝重、平均初生重、断奶仔猪数、断奶窝重及平均断奶重等6个繁殖性状指标的关联性。【结果】在柯乐猪BMP7基因上共发现5个SNPs位点:g.57602289C>T(第2外显子)、g.57602334C>T(第2外显子)、g.57602404C>T(第2内含子)、g.57602418C>T(第2内含子)和g.57602561G>T(第2内含子),均存在3种基因型;5个SNPs位点的优势基因型分别为CT、CT、CT、CT和GT,对应的多态信息含量(PIC)介于0.358~0.375,均表现为中度多态(0.25<PIC<0.50)。5个SNPs位点均符合Hardy-Weinberg平衡状态(P_(HWE)>0.05),且各SNP位点间均存在强连锁不平衡关系[LD系数(Dʼ)>0.800,相关系数(R^(2))>0.330]。关联分析结果显示,g.57602289C>T、g.57602334C>T和g.57602418C>T等3个位点TT基因型个体的初生窝重均显著高于CC基因型个体(P<0.05),TT基因型个体的断奶仔猪数极显著高于CC基因型和CT基因型个体(P<0.01,下同);g.57602404C>T位点TT基因型个体的总产仔猪数极显著高于CC基因型个体;g.57602561G>T位点TT基因型个体的总产仔猪数极显著高于GG基因型个体。此外,双倍型H2H2和H3H3个体的总产仔数、初生窝重、断奶仔猪数和断奶窝重均高于其他双倍型个体,尤其是H2H2个体在断奶仔猪数和初生窝重方面表现出明显优势。【结论】在柯乐猪BMP7基因上发现的5个SNPs位点均与其繁殖性能存在较强的关联性,BMP7基因可作为柯乐猪繁殖性状的候选基因,而双倍型H2H2可作为繁殖性状分子标记辅助选择的参考。

【Objective】The study aimed to identify the association between single nucleotide polymorphisms(SNP)loci of bone morphogenetic protein 7 gene(BMP7)and the reproductive performance of Kele pig,to explore molecular marker-assisted selection for reproductive traits in Kele pig,and to provide reference for accelerating the improvement of reproductive performance and the breed improvement process of Kele pig.【Method】A total of 150 healthy multiparous Kele sows were selected as the study subjects.SNP loci of the BMP7 gene were screened and identified using the Sanger sequencing method,and the population genetic parameters for each SNP locus were calculated.The association between SNP loci and 6 reproductive traits of Kele pigs,including total litter size,litter weight at birth,average birth weight,number of weaned piglets,litter weight at weaning,and average weaning weight,was analyzed using the general linear model(GLM)in SPSS 22.0.【Result】Five SNPs loci were identified in the BMP7 gene of Kele pigs:g.57602289C>T(exon No.2),g.57602334C>T(exon No.2),g.57602404C>T(intron No.2),g.57602418C>T(intron No.2)and g.57602561G>T(intron No.2),all of which exhibited 3 genotypes.The dominant genotypes for the 5 SNP loci were CT,CT,CT,CT and GT respectively,with corresponding polymorphism information content(PIC)ranging from 0.358 to 0.375,all exhibiting moderate polymorphism(0.25<PIC<0.50).All five SNP loci conformed to Hardy-Weinberg equilibrium(P_(HWE)>0.05),and strong linkage disequilibrium[LD coefficient(Dʼ)>0.800,correlation coefficient(R^(2))>0.330]was observed among all SNP loci.The results of the association analysis showed that individuals with the TT genotype at the 3 loci,g.57602289C>T,g.57602334C>T and g.57602418C>T,had significantly higher litter weight at birth compared to those with the CC genotype(P<0.05).The number of weaned piglets in TT genotype individuals was extremely significantly higher than in those with the CC and CT genotypes(P<0.01,the same below).The total litter size with the TT genotype individuals at the g.57602404C>T locus was extremely significantly higher than that of individuals with the CC genotype.The total litter size with the TT genotype at the g.57602561G>T locus was extremely significantly higher than that of individuals with the GG genotype.Additionally,individuals with the H2H2 and H3H3 diplotypes showed higher total litter size,litter weight at birth,number of weaned piglets,and weaning litter weight compared to other diplotypes,with H2H2 individuals demonstrating a particularly notable advantage in the number of weaned piglets and litter weight at birth.【Conclusion】Five SNPs loci identified in the BMP7 gene of Kele pigs are strongly associated with their reproductive performance.BMP7 gene can be considered a candidate gene for reproductive traits of Kele pigs,and the diplotype H2H2 can serve as a reference for reproductive traits molecular marker-assisted selection.