Genome-wide Association Studies For Pig Carcass Traits And Study Of Screening Backfat Thickness Main Effect Gene

This study analyzed the carcass traits from the genome level and the backfat trait was study indepth to screen the major candidate gene. The Large White×MinZhu F2resource group wasestablished and Genome-Wide Association Study (GWAS) was carried out using Illumina PorcineSNP60K DNA Chip for pig carcass traits. Then a significant area of backfat trait was in-depthanalyzed to screen major candidate gene. Research contents are as follows:1. The seven carcass traits containing head weight (HT), feet weight (FT), leaf fat weight (LFW),carcass length (CL), carcass weight (CW), backfat thickness (BFT) and slaughter body weight(SBW) were determined and described.2. According to the GRAMMAR-GC (Genome-wide Rapid Association using the Mixed Modeland Regression-Genomic Control) calculation method, GWAS were performed for HT, FT,LFW, CL, CW, BFT and SBW by using GenABEL under R-language environment and DMUsoftware in F2individual. The results showed the significant SNPs (P <1.03E–06) weredetected for six indexes, except of CW. The number of significant SNPs for HT, FT, LFW, CL,BFT and SBW were63,84,56,78,35and8respectively. All the significant SNPs werelocated on chromosome7and almost all were gathered in the31Mb to49Mb range,narrowing QTL range of carcass traits.3. The significant range of backfat trait was narrowed and located on chromosome70.50Mb(34755605-35332315) by haplotype analysis, selective sweep and P<0.01leve significantSNPs by GWAS. The narrowed range was blasted in Ensembl then six gene (HMGA1、GRM4、NUDT3、RPS10、SPDEF and PACSIN1), which have been annotated, were obtained.The fluorescence quantitative PCR for six genes were tested in backfat tissue of twoexperimental groups (60d/150d/210d old MinZhu and Large White pig test groups and60dold Erhualian pig and Large White pig test groups). The results showed HMGA1mRNA wasonly detected significant different expression. Therefore, HMGA1was identified as the majorcandidate for porcine backfat thickness.4. The RNAi test of HMGA1gene was performed on mouse3T3-L1preadipocyte cell lines.After induced differentiation for RNAi cells and negative control cells, cells were collectedand genes were tested by fluorescence quantitative PCR. Results showed that after interference, the mRNA expression of HMGA1、C/EBP-βand PPARγwere all significantlylowered (P<0.05). The results also showed that HMAG1played a role in3T3-L1preadipocytedifferentiating to adipocyte.