Abstract: 【Objective】 This study was aimed to explore the influence of genetic variation of insulin-like growth factor 1 receptor (IGF1R) gene on the growth traits of sheep (Ovis aries),in order to provide effective molecular genetic markers for the breeding of new breeds (lines) of high-quality mutton sheep.【Method】 Using liquid-phase capture sequencing technology to obtain IGF1R gene mutation sites in a total of 91 Doper sheep,Small-tailed Han sheep and Tan sheep,and screen out single nucleotide polymorphism (SNP) with significant differences among breeds.For the selected sites,flight mass spectrometry was used to detect 383 sheep of the hybrid offspring of 3 sheep breeds,and the correlation analysis with growth traits of newborn and 3 months old was carried out.【Result】 A total of 347 mutation sites were detected in IGF1R gene of 3 sheep breeds,there were 8 SNPs in exon:g.7628315 T>C,g.7628528 T>C,g.7628690 C>T,g.7833817 C>T,g.7836687 C>T,g.7840691 T>C,g.7855904 C>G and g.7872277 C>T.which showed polymorphism in the population.χ² test results showed that all SNPs were in Hardy-Weinberg equilibrium (expect for g.7628690 C>T in Small-tail Han sheep).g.7628528 T>C and g.7872277 C>T showed low polymorphism in 3 sheep breeds (PIC<0.25);g.7833817 C>T showed moderate polymorphism in 3 sheep breeds (0.25<PIC<0.50);The other 5 SNPs showed moderate polymorphism in 1 or 2 populations.The single-site association analysis showed that g.7628528 T>C was significantly correlated with the 3 months old body weight and chest girth of F2 generation,and the newborn chest girth of H2 generation (P<0.05);g.7628690 C>T was significantly correlated with the newborn chest girth of H2 generation (P<0.05);g.7833817 C>T was significantly correlated with the 3 months old body height of F2 generation (P<0.05);g.7836687 C>T was significantly correlated with the 3 months old body weight and chest girth of F1 generation,and the 3 months old body height of F2 generation (P<0.05);g.7755904 C>G was significantly correlated with the 3 months old chest girth of F1 generation,and the newborn chest girth of F2 generation (P<0.05);g.7872277 C>T was significantly correlated with the 3 months old chest girth of H1 generation,the newborn body weight,body height,chest girth,and 3 months old body height of H2 generation (P<0.05);g.7628315 T>C was significantly correlated with the 3 months old body height and body length of F1 generation,and the 3 months old body height of H2 generation (P<0.05);g.7840691 T>C had no significant association with growth traits (P>0.05).Linkage disequilibrium analysis showed that g.7628315 T>C-g.7628528 T>C and g.7833817 C>T-g.7840691 T>C formed 2 strong linkages,3 haplotypes were constructed,and 6 genotypes were formed after combination,the dominant genotypes were H2H2 and H5H6,respectively.The association analysis of haplotype combination showed that the newborn body length of H3H1 genotype individuals was significantly higher than that of H3H2 genotype (P<0.05),and the 3 months old body height of H2H2 genotype individuals was significantly higher than that of H1H2 genotype (P<0.05),the 3 months old body length of H4H5 genotype individuals was significantly higher than that of H4H6 genotype (P<0.05),and there were no significant differences in other growth indicators among the combined genotypes (P>0.05).【Conclusion】 The results of this study indicated that the genetic variation of IGF1R gene had an significant impact on the growth traits of sheep.8 SNPs caould be considered as potential candidate genetic markers during the growth and development of sheep,which could provide information for the selection and breeding of IGF1R gene in mutton sheep,and provide the theoretical basis for the molecular marker-assisted breeding of mutton sheep.

Key words: sheep; IGF1R gene; growth traits; association analysis