小型黑羽鸡羽色性状与MC1R基因的关联研究

Study on the Association between Feather Color Traits and MC1R Gene in Local Small Black Feather Layers

为筛选与小型黑羽鸡培育品系黑羽性状相关的SNP位点,获得黑羽性状的分子标记。选取成年小型黑羽鸡和洛岛红标准品种鸡公母各30只(公母配比为1∶1)进行正反交试验,对亲本MC1R基因外显子进行PCR扩增并测序,将个体的MC1R基因多态性与后代羽色性状进行关联性分析,并对筛选出的相关遗传标记在大群中进行检测和进一步杂交验证。结果显示:正反交共得到476只F_(1)代,其中正交F_(1)代有黑羽236只,黄羽51只;反交F_(1)代有黑羽123只,黄羽66只。无论正交还是反交,均只有后代纯黑羽的组合,而无后代纯黄羽的组合,表明该群体黑羽性状属于常染色体显性遗传;黑、黄羽两种羽色的比例基本符合1∶1的分离比(黑羽∶黄羽=104∶98),表明黑羽性状受到一对等位基因控制;在MC1R基因编码区发现共有3个突变(C67T、T211C、G277A),其中后两个为错义突变;CTG单倍型在小型黑羽鸡群体中出现频率最高(0.666),且其杂交后代羽色基本为纯黑羽表型;通过大群验证发现与前期结果一致,父本单倍型为纯合的CTG的后代均表现为黑羽表型。综上,小型黑羽鸡黑羽性状为常染色体显性性状,MC1R基因CDS区上的突变(CTG单倍型)与黑羽性状紧密相关。

The aim of this study was to screen out the SNP loci associated with the black feather trait in local small black feather chicken and obtain the molecular marker for black feather.30 male and 30 female adult local small black feather chickens and 30 male and 30 female Rock Island Red standard breed chickens(male to female ratio:1∶1)were selected for pure and reciprocal crossing,and the exons of MC1R gene of the parents were amplified and sequenced.Individual MC1R gene polymorphisms were correlated with offspring plumage traits,and the screened relevant genetic markers were tested and further crossed for validation in large populations.The results showed that a total of 476 F_(1) generations were obtained from the pure and reciprocal crosses,including 236 black and 51 yellow chicks in the pure cross F_(1) generation,and 123 black and 66 yellow chicks in the reciprocal cross F_(1) generation.In both crosses,there were only combinations of progeny with pure black plumage and no combinations of progeny with pure yellow plumage,indicating that the black feather trait was autosomal dominant in this population.The ratio of the two plumage colors was basically in accordance with the 1∶1 segregation ratio(black∶yellow=104∶98),indicated that the black plumage trait in this population was controlled by a pair of alleles.A total of three mutations(C67T,T211C,G277A)were found in the coding region of MC1R gene,the latter two of which were missense mutations.Haplotype and post-hybrid phenotype analysis of these three loci revealed that the CTG haplotype was the most frequent(0.666)in the black feather chicken population,and the plumage color of its offspring was basically pure black plumage phenotype.The large group validation was consistent with previous results that progeny with pure parental haplotype CTG all exhibited the black feather phenotype.The black feather trait in this population was an autosomal dominant trait,and mutations in the CDS region of the MC1R gene(haplotype CTG)were strongly associated with the black feather trait.