Studies On Association With Egg Production Of Candidate Gene In Hypothalamic–Pituitary-Gonadal Axis In Xinhua Chicken

The production and quality of eggs are closely related to the national economy and people’s life.The potential of egg production based on local breeds of chickens is huge.Xin Hua chicken is matching with local chicken breeds cultivation resistance and the resistance of forage,and the advantages of strong adaptability,but low heritability traits(Open Day age,number of eggs and egg quality,etc.)with conventional breeding methods to improve is not ideal.This study Xin Hua chicken E system as experimental material,the PCR-RFLP method of DRD2,IGF 1,HDLBP and ADRA1 beta gene classification,the use of molecular biology methods of four genes in reproductive growth axis SNPs loci polymorphism and eggs with trait and correlation analysis,hope to screening of potential molecular markers,in order to speed up the Xin Hua chicken breed improvement and breeding.The experimental results of this study are as follows:1.Analysis of tissue expression profiling of DRD2,IGF-1,HDLBP and ADRA1β genes revealed differences in the expression of heart,liver,kidney,brain,pectoral muscle,fallopian tubes,and pituitary of Xinhua hens at different stages.2.A total of 31 SNPs of DRD2,IGF-1,HDLBP and ADRA1βwere located in the regulatory regions,introns,and exons,detected by one-generation sequencing and PCR-RFLP.(1)Association analysis of SNP loci and egg production traits:The sites associated with DRD2 gene SNP1 and SNP4 were correlated with age at first egg(AFE);the site associated with egg number(EN)was SNP2;SNP3 was related to the weight at first egg(WFE),primary egg weight(EW),and largest Clucth Size(LCS).The sites associated with IGF-1 gene AFE were SNP5 and SNP6 sites;the sites related to EN were SNP8 and SNP5 sites;the SNP7 was related to WFE and LCS.The SNP9 site of the HDLBP gene is related to the WFE and LCS.The SNP10 site of the ADRA1β gene is associated with the length of the LCS and the EN.(2)Association analysis between SNP loci and egg quality traits:The sites of DRD2 gene related to yolk weight(YW)are SNP1,SNP2,SNP4 sites;the sites associated with Haugh unit(HU)are SNP1 and SNP4 sites;and the SNP3 is related to eggshell Strength(ESS);the site associated with the yolk color(YC)is the SNP1;the site associated with the albumen weight(AW)is the SNP4 site.The SNP8 site of the IGF-1 gene is related to the egg shape index(ESI).The SNP9 site of the HDLBP gene is related to the HU.The SNP10 site of the ADRA1β gene correlates with ESS.3.Association analysis of haplotype combinations: The combinations of the four sites of the DRD2 gene(SNP1,SNP2,SNP3,and SNP4)were significantly associated with LCS.(P=0.00146<0.01),which is correlated with the HU(P=0.047<0.05).TThe combinations of the four sites of the IGF-1 gene(SNP5,SNP6,SNP7,and SNP8)was significantly associated with the average clucth size(P=0.0013<0.01),was significantly associated with LCS(P=0.019<0.05),and was significantly associated with the HU(P=0.011<0.05).4.Predictive analysis found that the mutation in the SNP8 site of the IGF-1 gene was located in the non-core region of the transcription factor,and the mutation did not occur in the conserved base of the transcription factor;the SNP10 site in the ADRA1β gene was not Synonymous mutations result in the mutation of aspartate(D)to glycine(G).5.Evolutionary analysis found that the evolutionary tree constructed based on the coding sequences of DRD2,IGF-1,HDLBP,and ADRA1β genes,using the neighboring method(Neighbo-Joining)and the maximum likelihood method of MEGA6.0 software,and the protein according to the codeml.The amino acid sequence substitution model programs Model1 and Model2,Model7 and Model8 were used for positive selection test among species,and it was found that the ω values of Model0 of DRD2,IGF-1,HDLBP and ADRA1β genes were all less than 1,and the gene was purified and selected,which means that the gene was positively selected after replication.In this study,SNP association analysis,joint haplotype association analysis,prediction and phylogenetic analysis were performed.It was found that the DRD2 gene and IGF-1 gene were associated with Xinhua egg traits,presumably serving as candidate genes affecting egg traits;HDLBP gene and ADRA1β Only a single locus of the gene is associated with the egg trait,and its use as a candidate gene requires further verification between larger groups and more generations.