Genetic Analysis Of Fatness Traits QTL On Porcine Chromosome 7q1.1-1.4 Region

QTL affecting fat deposition traits such as backfat thickness on chromosome 7 p1.1-q1.4 region were reported in many studies, as well as QTL between Sw1856-Sw859 affecting backfat thickness in F2 resource population in our lab. In virtue of newly released porcine genome sequence map, we selected 10 positional candidate genes in this region and screened part of SNP in these genes with comparative sequencing method, and then constructed the linkage map for further QTL mapping in the pig resource family of Large White×Meishan. Specific results are as follows:1. We selected 6 candidate genes in Sw1856-Sw859 region and obtained 22 new SNP markers in these genes. Meanwhile, genotyping methods of 6 molecular markers were established. In order to increase markers density, the existing four SNP markers reported in NCBI database were also included. Therefore, a total of 10 SNP markers were used across 20Mb. SNP genotyping of Large White X Meishan resource including 315 F2 pigs were performed by RFLP methods. Eight informative polymorphic sites (polymorphism information content 0.359～0.375) were used for linkage mapping. The sex-averaged linkage map spanned 24.6cM, with an average interval of 3.51cM.2. Linear model and least square regression interval mapping was used for detecting the QTL of 7 fat deposition traits. The F threshold values were determined by permutation. In all,5 QTL were detected at 5% chromosome-wise level, of which four QTL reached 1% chromosome-wise level.①The significant QTL affecting BFT2 at position 23cM between GNMT and PLA2G7 could explain approximately 5.207% fraction of the phenotypic variation. Large White allele caused an increase in BFT2.②The significant QTL for BFT3, BFT4, ABF and LFW were all mapped to the same marker interval between PPARD and GLP1R. Four QTL for BFT3, ABF, BFT4 and LFW explaining respective 4.999%,3.975%,4.668% and 4.575% of the genetic variance were found with high significance at positions 11 and 12 cM on SSC7 q1.1-1.4, with the Meishan allele decreasing the phenotypic value.