Polymorphism Of GHR,GHRH,GHRL Gene And Its Association Analysis With Growth Traits In Sheep

In order to screen out candidate genes that affect the growth of high-quality mutton sheep in Ningxia,this study used the three parent groups of Dorper,Small Tail Han sheep,and Tan sheep and their hybrid offspring as the research objects.Targeted sequencing technology was used to detect the GHR,GHRH,and GHRL gene differential sites of the three parent populations,and the bioinformatics analysis of missense mutations in the exon region was performed;MassArray genotyping technology was used to detect the differential site genotypes of the hybrid offspring and analyzed the correlation of growth traits between different genotypes;The qRT-PCR technology was used to analyze the expression of related genes in different tissues,and the GHRH genes with promoter mutations were further analyzed for the relationship between SNP and gene expression.The main findings are as follows:1.The part of GHR,GHRH,and GHRL genes of 91 sheep from 3 breeds were sequenced by targeted sequencing technology,and 41 sites with significant differences among populations were screened.The three genes are in Dorper sheep,Tan sheep,and Small Tail Han sheep.There are significant differences among the three different breeds of sheep.2.MassArray genotyping technology was used to genotype the different sites in 3 84 hybrid offspring sheep and perform correlation analysis with growth traits.The results showed that the initial indicators of CC and CT genotype individuals at 33627336 site of the GHR gene exon region were significantly higher(P<0.01)than TT genotype individuals,and the six-month-old body length was significantly higher(P<0.05).In the TT genotype individuals;the initial body height,chest circumference,and three-monthold body length of the GG and AG genotypes at 33661895 were significantly higher than those of the AA genotype individuals(P<0.05),and the three-month-old body weight of the AG genotype individuals was significantly higher In the AA type(P<0.05);the diplotype H1H2,H2H2,H1H4,H2H4 type individuals composed of have higher indicators in each period than the H1H3,H3H3,H3H4 type individuals and there are certain differences.There was no significant correlation between genotype and individual indicators of GHRH gene 69000912,69001024,69001075,69001149 sites.In the exon region of the GHRL gene,individuals with TG genotype at position 56243237 at 6-year-old have significantly higher body heights than those with GG type(P<0.05);individuals with TA type at position 56243237 have a significantly higher body weight,height,and length than TT at 6-month-old(P<0.05);The six-month-old body height and chest circumference of H1H2 diplotype individuals were significantly higher than those of H2H2 individuals(P<0.05).3.The tissue expression of the three genes was studied by qRT-PCR technology,and it was found that the three genes were mainly expressed in liver,brain and pituitary tissues,and their expression levels in muscle tissues were low.The SNP mutation at 69000912 in the upstream region of the GHRH gene was related to the expression of the gene in the brain tissue,and the GT type was significantly higher than the TT type(P<0.05).In summary,the 33627336 and 33661895 sites of the GHR gene and the 56243223 and 56243237 sites of the GHRL gene are related to sheep growth traits.They have a certain reference value in breeding work,and can use it as a candidate gene locus for the growth and meat production performance of mutton sheep for further research.