西藏山羊高海拔适应性的选择信号筛选

Detection Selection Signatures for High-altitude Adaptation in Tibetan Goats

试验旨在对西藏山羊常染色体的选择信号进行筛选,发掘重要的种质特性基因。基于西藏山羊、新疆山羊和太行山羊群体的Illumina 50K芯片分型数据,通过过滤等位基因频率较低和未定位的变异位点,得到高质量的SNPs标记;通过计算遗传分化系数(Fst)来分析群体遗传结构,同时对群体进行主成分分析(principal component analysis,PCA)和系统进化树构建以确定其群体结构;借助Di和XP-EHH两种不同的方法,以前5%为阈值,通过SNPs注释得到西藏山羊基因组受选择基因,并利用相关的生物信息学数据分析库对候选基因进行功能富集分析。结果显示,在3个群体中共鉴定出48358个SNPs标记,3个群体有相近的遗传距离(Fst<0.05),西藏山羊的遗传分化程度(Fst=0.0376)明显高于新疆山羊(Fst=0.0256)、太行山羊(Fst=0.0257),表明西藏山羊群体已经产生一定程度的遗传分化。通过选择信号分析,在西藏山羊群体中共筛选到36个受到较强选择的位点和211个候选基因,其中EGFR、AKT1、PDHB和PFKP等基因与高海拔适应性相关。这些基因主要富集在嘌呤代谢通路、代谢途径和HIF-1信号通路等。利用基因组SNP标记可以更全面地揭示西藏山羊高海拔适应性的选择进展,为种质资源的保护和利用提供重要参考。

This study was aimed to screen the selection signatures on autosome of Tibetan goats and discover genes with important germplasm characteristics.Based on the Illumina 50K chip genotyping data of Tibetan goats,Xinjiang goats and Taihang goats,high quality SNP markers were obtained after filtering out SNPs with low allele frequency and not located.The genetic structure was analyzed by genetic differentiation coefficients(Fst).Meanwhile,the principal component analysis(PCA)and phylogenetic tree construction were conducted to determine the population structure.The selected genes in Tibetan goats were also identified through genome selective signals testing,which contained Di and XP-EHH with top 5%valued as a significant threshold.To identify the genes that were under selection,bioinformatics databases were examined that contained relevant data on goats.The results showed that 48358 SNPs were identified in these three populations.Population genetic analysis showed that the three groups had similar genetic distance(Fst<0.05),but the degree of genetic differentiation of Tibetan goats(Fst=0.0376)was significantly higher than that of Xinjiang goats(Fst=0.0256)and Taihang goats(Fst=0.0257),indicating that Tibetan goats breed had already generated a certain degree of genetic differentiation.Based on these SNPs,36 SNPs and 211 genes were identified in Tibetan goats by Fst and XP-EHH.Among them,EGFR,AKT1,PDHB and PFKP genes were related to high altitude adaptation.These genes were found to be mainly enriched in purine metabolism pathway,metabolic pathway and HIF-1 signaling pathway.In conclusion,the genomic SNPs had more advantage in revealing the selection of Tibetan goats in high-altitude adaptability,and provided new theoretical references for the protection and utilization of germplasm resources.