TGF-β1基因多态性及其与2个山羊品种产羔数的相关分析

Polymorphism of TGF-β1 gene and its relationship with litter size in two goat breeds

为了研究波尔山羊和陕南白山羊转化生长因子β1(TGF-β1)基因遗传多态性及其与产羔数的相关性,根据绵羊TGF-β1基因序列设计3对引物,采用PCR-SSCP技术和DNA测序技术检测山羊TGF-β1基因外显子1和内含子2的多态性,同时用最小二乘法探讨了其多态性与产羔数的关系。结果显示,在波尔山羊和陕南白山羊中,仅第2内含子(P2)存在多态位点,分别定义为MM、LM和LL基因型。MM型与LL型相比在内含子2的790bp处碱基发生G→C的突变,多态位点均以L为优势等位基因,基因频率分别为0.540和0.659。在波尔山羊的3～4胎和平均产羔数中,MM型个体的产羔数显著高于LM和LL型个体(P<0.05);LM型个体的第2胎产羔数显著高于LL型个体(P<0.05)。在陕南白山羊的2～4胎和平均产羔数中,MM型个体显著高于LM和LL型个体(P<0.05)。表明TGF-β1基因多态位点与产羔数显著相关,可用于山羊分子遗传育种的候选基因。

The. objectives of the present study were to detect the polymorphism in transforming growth factor-β1 （TGF-β1） and investigate the relationship between TGF-β1 gene and litter size in Boer and Shaannan goat breeds. According to the sequence of ovine TGF-β1 gene, three pairs of primers were designed to detect single nucleotide polymorphism of the exon 1 and intron 2 of TGF-β1 gene in two goat breeds by PCR-SSCP and DNA sequencing. The least square mean and genetic variance of different genotypes at polymorphic loci were analyzed. The results showed that only the products amplified by primer 2（P2） displayed polymorphism. Three genotypes（LM, MM and LL）,and one single nucleotide mutation（G-C） were detected in two goat breeds. Haplotype L was the dominant allele. The frequencies of haplotype L were 0. 540 and 0. 659 in two goat breeds,respectively. In Boer goat,MM genotype had significant higher（P〈0.05） litter size than LM and LL genotype in the third or fourth parity and average parity;LM genotype had significant higher（P〈0.05） litter size than LL genotype in the second parity. In Shaannan goat,MM genotype had significant higher（P〈0.05） litter size than LM and MM genotype in the second or fourth parity and average parity. The TGF-β1 gene was shown to be associated with litter size in two goat breeds. Therefore,these results suggest that the TGF-β1 gene is a strong candidate gene that af- fects litter size in goats.