Abstract: Uniformity of plumage color is a critical breeding objective for the Luokeng chicken，a distinctive indigenous breed in Guangdong Province. To elucidate the genetic basis underlying plumage color variations，this study investigated the polymorphisms of the melanocortin? 1 receptor（MC1R）gene across three phenotypes：dark partridge，light partridge，and yellow. The complete coding region of MC1R was amplified and screened for single nucleotide polymorphisms（SNPs）using PCR combined with Sanger sequencing. Sequence analysis identified two significant missense mutations in the coding region：a c.274G>A substitution resulting in a glutamic acid?to?lysine change at residue 92（p.Glu92Lys），and a c.265T>C substitution leading to a serine to proline change at residue 89（p. Ser89Pro）. Genotyping and association analysis revealed a highly significant correlation between the c.274G>A locus and plumage phenotypes（P<0.01）. Specifically，the AA genotype was predominant in the dark?partridge population （frequency：97.44%），whereas the light?partridge and yellow populations consisted primarily of AG heterozygotes and GG homozygotes. These findings confirm that c.274G>A is the major effect locus controlling plumage color in Luokeng chickens. Consequently，marker?assisted selection（MAS）based on this locus can precisely identify and eliminate recessive heterozygous carriers，thereby significantly accelerating the purification and rejuvenation process of the Luokeng chicken breed.

Key words: Luokeng chickens；MC1R gene；marker?assisted selection（MAS）

摘要： 罗坑鸡是广东省第三次畜禽资源普查发现的新资源，是优良的地方家禽品种，羽色 外貌特征呈现出较多样化。为解析罗坑鸡羽色性状的遗传机制，研究以群体中全麻羽、轻麻羽 及黄羽三种典型表型个体为素材，针对候选基因黑素皮质素受体1基因（MC1R）开展了序列变 异分析。研究采用PCR扩增结合Sanger测序技术，筛查出关键的单核苷酸多态性（SNP）位点。 序列比对结果显示，MC1R 基因编码区存在两处错义突变：一是位于第274 位的c.274G>A 突 变，导致第92 位氨基酸由谷氨酸（Glu）突变为赖氨酸（Lys）；二是位于第265 位的c.265T>C 突 变，导致第89位氨基酸由丝氨酸（Ser）变为脯氨酸（Pro）。基因分型与关联分析表明，c.274G> A 位点基因型在不同羽色群体间的分布差异极显著（P<0.01）：全麻羽群体中AA基因型为优势 基因型（检出率高达97.44%），而轻麻羽及黄羽个体则主要以AG杂合型和GG基因型形式存 在。结果提示，基因c.274G>A 可能是调控罗坑鸡羽色性状的关键候选位点，可利用该位点建 立分子标记辅助选择技术，精准识别并剔除隐性基因携带者（杂合子），为加速罗坑鸡羽色性 状的提纯复壮提供有效的分子育种方法。

关键词: 罗坑鸡；MC1R 基因；分子标记辅助检测