GWAS Of Internal Organ And Carcass Weights And Genetical Dissection On The Pork C20:0 Fatty Acid Composition

With the development of the in-depth study of genomics and high-density gene chip technology, numerous genetic variants associated with complex traits had been identified by the whole-genome association study(GWAS). In recent years, this approach has been applied in the identification of major gene in economically important traits of agricultural animals. Pig, as the most important economic animals of provisions of meat, has obtained more attentions on the research of its important economic traits.2650 individuals from five experimental populations(the F2 resource population, Sutai population, Laiwu population, Erhualian population and DLY commercial population) are included in this study. Seven important economic traits, which include 4 internal organ(heart, liver, spleen and kidney) weights, carcass weight and C20:0 content were recorded. The genotype data are produced using Pocine SNP60 beadchip. GWAS and meta-GWAS were conducted to identify the major QTL(quantitative trait loci) associated with the traits studied. To furtherly fine map the QTL associated with C20:0 content, we adopted comprehensive application of many statistical methods, such as, haplotype analysis, IBD(identical-by-decent) analysis. The findings will contribute to further identification of the QTG(quantitative trait gene) and QTN(quantitative trait nucleotide) underlying the QTL and understand the genetic architure of the C20:0 content in muscle.The results show that,1) A total of 10 genome-wide significant QTL were identified in GWAS from five populations. Of which, 4 was association with heart weight, 2 with liver weight, 2 with spleen weight, one with carcass weight and one with C20:0. We also find one pleiotropic QTL in chromosome 7, which was association with heart weight and liver weight.2) Sixty-two percent of genome-wide significant QTL identified in singe-GWAS were verified in meta-GWAS. Additionally, 4 novel suggestive QTL associated with carcass weight were discovered in meta-GWAS.3) After the comprehensive application of haplotype analysis, IBD analysis and meta analysis, we located the QTL associated with C20:0 content to 41.3- 43.4Mb and a candidated gene ELOVL7 standed out.4) Eleven SNPs(single nucleotide polymorphisms) consistent with QTL genotype were identified by taking advantage of the resequencing data of 6 F0 pigs. Two SNPs(42561841 and 42564441bp) were kept after verification in F2 and Sutai populations.5) To verify the biological effects of ELOVL7, we randomly selected 120 individuals from F2 population to conduct the RNA expression. The e QTL analysis indicated that the strongest SNP is ALGA0090412 at 40.7Mb near the ELOVL7Our study will lay the foundation for understanding the genetic structure of internal organs and carcass weights and give insights into the molecular genetic mechanisms of C20:0 in pig’s muscle.