Genetic variation of porcine thyroid-stimulating hormone β subunit gene (TSH-β) and its association with the economic important traits | 猪促甲状腺激素β基因(TSH-β)多态分布及与经济性状的关联分析

Chinese. 为研究猪促甲状腺激素β基因(TSH-β)的多态分布情况及与生长肉质性状的关联性，本研究对TSH-β基因全序列进行再测序，发现3个单核苷酸突变座位：位于5'非转录区多态座位A-175G、位于编码区非同义突变座位G+52A，以及位于内含子的突变座位G+570A。采用PCR-RFLP和四引物ARMS-PCR方法对皮特兰、长白、杜洛克、约克夏、金华猪、岔路黑猪和嘉兴黑猪七个纯种猪群以及金皮资源家系F2代群体共计548头个体进行多态分型，并在F2代群体中分析了TSH-β多态座位与生长和肉质性状的关联性。结果表明，猪TSH-β基因具有较高的遗传多样性(Shannon多样性指数总体均值为0.48)，且存在相当程度的品种间遗传分化(Fst=0.5389)。其中，座位A-175G在4个国外品种和岔路黑猪中的优势等位基因为A，而在金华猪和嘉兴黑猪中的优势等位基因为G，关联分析显示AA型个体在胴体长、日增重、后腿重和后腿肌肉重方面显著高于GG型个体(P0.05)；座位G+52A的多态性主要存在于金华猪中，而在其他猪种中表现为低杂合度或完全纯合于等位基因G，且与肌内脂肪含量有显著关联；座位G+570A的多态性仅存在于我国的嘉兴黑猪和金华猪中，其他猪种表现为完全纯合于等位基因G，关联分析结果表明GG型个体在胴体长和后腿肌肉重方面显著高于AA型个体。研究结果提示，TSH-β基因可考虑为猪4号染色体相关QTL的功能候选基因。

English. 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 (P0.05) 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.