关键词: 罗坑鸡；MC1R 基因；分子标记辅助检测

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）