Abstract：The objective of this study was to identify polymorphisms of porcine thyroid-stimulating hormone β subunit gene (TSH-β) and investigate its associations with porcine carcass and meat quality traits. Three SNP were identified by resequencing the entire genomic sequence of porcine TSH-β gene: A-175G located in the 5' untranscribed region, non-synonymous mutation G+52A located in the coding region and G+570A located in the intron. These three loci were genotyped in total of 548 pigs which including 24 Pietrain, 28 Landrace, 30 Duroc, 57 Yorkshire, 49 Jinhua pigs, 33 Chalu black pigs, 41 Jiaxing black pigs and 286 F2 animals of a cross of Pietrain and Jinhua pigs by PCR-RFLP and tetra-primer ARMS-PCR methods. Association study was carried out in the F2 population. Considerable genetic diversity of porcine TSH-β gene (Shannon I = 0.48) and gene differentiation among breeds(Fst=0.5389) were observed. The prevailing allele of locus A-175G in the four foreign breeds and Chalu black pigs was A, while it was G in Jinhua and Jiaxing black pigs. And association analysis showed that animals with AA genotype were significantly higher (P<0.05) than individuals with GG genotype in carcass length, daily gain, ham weight and ham muscle weight. The polymorphism of locus G+52A was mainly observed in Jinhua pig, and it was significantly associated with intramuscular fat content. The polymorphism of locus G+570A was only observed in Jinhua and Jiaxing black pigs, and it seemed to be fixed for G allele in the other breeds, association analysis revealed that the carcass length and ham muscle weight were significantly higher in pigs with GG genotype than that with AA genotype. The results suggested that TSH-β can be the functional candidate gene for the corresponding QTLs located on Sus scrofa chromosome 4.
