柯乐猪PRLR基因多态性与繁殖性状的关联性

Correlation of PRLR gene polymorphisms and reproductive traits in Kele pig

本研究旨在探究催乳素受体(prolactin receptor,PRLR)基因的单核苷酸突变位点(single nucleotide polymorphism,SNP)及其对柯乐猪繁殖性状的遗传效应,以期为提高柯乐猪的繁殖性能研究提供基因标记。采用PCR产物直接测序法对204头柯乐猪PRLR基因外显子区的SNP位点进行筛查鉴定,同时利用SPSS软件中单因子方差法分析各SNPs不同基因型和双倍型与7个繁殖性状的相关性,并通过在线软件分析碱基变异对mRNA二级结构的影响。结果显示,在柯乐猪PRLR基因第8外显子检测到g.20655220 C>T突变,其导致丝氨酸变成脯氨酸,为错义突变;在第4内含子检测到2个同义突变位点g.20648859 C>T和g.20648931 C>T,3个SNPs均存在3种基因型,g.20648931 C>T属于低度多态,其余2个位点属于中度多态;经卡方χ^(2)检验,g.20655220 C>T位点的基因型分布符合Hardy-Weinberg平衡(P>0.05),g.20648859 C>T和g.20648931 C>T位点的基因型分布极显著(P<0.01)偏离Hardy-Weinberg平衡;g.20655220 C>T位点导致PRLR基因mRNA序列二级结构发生改变,致使mRNA二级结构稳定性降低;3个SNPs共组成5种单倍型和9种双倍型,优势单倍型H1(CCC)频率为0.610,优势双倍型H1H1(CCCCCC)频率为0.382。关联性分析结果显示,g.20655220 C>T位点CC基因型母猪的初生个体重、断奶窝重和断奶个体重均显著(P<0.05)高于CT基因型,g.20648931 C>T位点CT基因型母猪的初生个体重、初生窝重和断奶窝重均显著(P<0.05)高于CC基因型和TT基因型,且该位点在初生个体重上,CC基因型显著(P<0.05)高于TT基因型;双倍型H1H5(CTCTCT)在产仔数和活仔数上为优势双倍型,H2H3(CCTTCT)在断奶窝重和断奶个体重上为较优双倍型。综上,PRLR基因可作为候选基因参与柯乐猪繁殖性状的分子标记辅助选择。

The aim of this study was to investigate the polymorphisms of the prolactin receptor gene(PRLR)and their effects on reproductive performance in Kele pigs,with a view to finding molecular markers for improving reproductive performance in Kele pigs.In this study,SNPs in the exon region of the PRLR gene were screened in 204 Kele pigs and identified by direct PCR product sequencing.At the same time,the correlation between different genotypes and diplotypes of SNPs and seven reproductive traits was analysed by single-factor variance method in SPSS software,and the influence of base variation on the secondary structure of mRNA was analysed by online software.The results showed that g.20655220C>T mutation was detected in the 8th exon of PRLR gene,which caused serine to proline change,which was a missense mutation.Two synonymous mutations g.20648859C>T and g.20648931C>T were detected in the fourth intron.There were three genotypes in all three SNPs,g.20648931C>T was low polymorphism and the other two loci were medium polymorphism.Chi-squared test showed that the genotype distribution of g.20655220C>T loci was in Hardy-Weinberg equilibrium(P>0.05).The genotypes of g.20648859C>T and g.20648931C>T deviated significantly(P<0.01)from Hardy-Weinberg equilibrium;g.20655220C>T locus led to changes in the secondary structure of the PRLR gene mRNA sequence,resulting in decreased stability of the secondary structure of the mRNA;the three SNPs consisted of 5 haplotypes and 9 diplotypes.The dominant haplotype H1(CCC)frequency was 0.610 and the dominant diplotype H1H1(CCCCCC)frequency was 0.382.Correlation analysis showed that the average birth weight,weaning litter weight and weaning average weight of CC genotype were significantly(P<0.05)higher than those of CT genotype.CT genotype of g.20648931c>T locus had significantly(P<0.05)higher birth weight,birth litter weight and weaning litter weight than those of CC genotype and TT genotype,and CC genotype had significantly(P<0.05)higher birth weight than that of TT genotype.H1H5(CTCTCT)was the dominant doublet type in terms of litter size and live litter size,whereas H2H3(CCTTCT)was the superior doublet type in terms of litter weight and average weaning weight.In conclusion,PRLR gene could be used as a candidate gene for molecular marker-assisted selection of breeding traits in Kele pig.