不同尾型绵羊全基因组选择信号检测

Genome-wide Detection of Selection Signatures of Distinct Tail Types in Sheep Populations

为研究不同尾型绵羊群体遗传分化程度,检测全基因组选择信号,以挖掘不同尾型绵羊重要性状相关的候选基因。本研究基于蒙古羊(短脂尾)和藏羊(瘦尾)群体的Illumina Ovine SNP 50K芯片分型数据,借助遗传分化系数FST法进行群体间选择信号检测,寻找选择信号区域内的重要基因,并对其中与脂肪代谢相关的基因PPARG、PDGFD在呼伦贝尔羊(大尾和小尾品系;肥尾)与藏羊(瘦尾)尾脂进行mRNA相对表达量研究。结果,(1)465个SNPs被选择,基因注释找到448个候选基因,筛选到50个与脂类代谢相关的基因,GO功能富集分析发现,主要富集在脂类生物合成过程、磷脂代谢、脂质结合等条目,此外发现4个基因(PPARG、RXRG、SLC27A2和ACSL6)富集到PPAR信号通路。(2)肥瘦尾之间,呼伦贝尔羊(大尾和小尾品系)PPARG和PDGFD基因表达量均显著高于藏羊(P<0.01),而大小肥尾之间,呼伦贝尔羊大尾品系PPARG基因表达量显著高于小尾品系(P<0.05),PDGFD基因表达量则无明显差异。通过FST法有效检测到受选择的基因,部分与绵羊重要性状相关,相对定量试验证明PPARG和PDGFD基因与尾部脂肪沉积密切相关,可以作为尾型选育的候选基因,为绵羊育种及改良提供重要参考。

This experiment was conducted to study genetic differentiation between 2sheep populations with distinct tail types by genome-wide detection of selection signatures and to search the candidate genes related to important traits of sheep.Based on the Illumina Ovine SNP 50 KBreadchip genotyping data of Mongolian sheep and Tibetan sheep,population differentiation index FST was adopted to detect the selection signatures,and to found the genes located in selection signature regions.Based on the tail adipose tissue of Hulun Buir sheep(fat-tailed sheep,include large fat-tailed sheep and small fat-tailed sheep)and Tibetan sheep(thin-tailed sheep),the relative expression study was adopted to explore the difference of gene relative expression level of PPARG and PDGFD,which were related to fat metabolism.This result showed that:(1)465selected SNPs were found,448 candidate genes were detected by gene annotation.And 50 genes related to lipid metabolism were selected from these candidate genes,the analysis of GO showed that these genes were related to lipid biosynthetic process,phospholipid metabolic process and lipid binding.In addition,4genes were found,PPARG,RXRG,SLC27A2 and ACSL6,and enriched into the PPAR signaling pathway.(2)The gene relative expression levels of PPARGand PDGFDfrom Hulun Buir sheep was significantly higher than that of Tibetan sheep(P<0.01),between fattailed and thin-tailed sheep,the gene relative expression level of PPARGfrom lager fat-tailed Hulun Buir sheep was significantly higher than that of small fat-tailed Hulun Buir sheep(P<0.05),but the gene relative expression level of PDGFD had no significant difference between lager fattailed and small fat-tailed Hulun Buir sheep.FST could be used to detect the genes with selection signatures and some of the candidate genes were related to important traits in sheep.PPARGand PDGFDgenes were proved to be closely related to tail fat deposition through the relative expression studies,these genes could be used as candidate genes for different tailed sheep breeding.This study can provide theoretical references for sheep breeding or breed improvement.