1. Tile-grey plumage is a unique and rare feather type of local chicken breeds in China, but its genetic mechanism and corresponding genes remain unknown.

2. In order to identify the genetic basis and molecular characteristics of tile-grey plumage, this experiment investigated variations of melanocortin 1 receptor (MC1R) gene in Yunnan Piao chickens with typical tile-grey plumage characteristics in contrast with three Yunnan local breeds as well as two standard breeds with different plumage colour, and analysed the association between genic variation and tile-grey plumage.

3. Through sequencing and comparison of the entire coding region of the MC1R gene, a total of 10 SNP loci were detected, of which eight were non-synonymous mutations that cause amino acid changes. The gene frequency and genotype frequency of the MC1R mutation sites in different breeds and different plumage colour groups revealed that C69T, T212C and A274G were significantly associated with tile-grey plumage. Eighteen haplotypes of the MC1R gene were constructed based on 10 nucleotide variations and eight amino acid variations. Haplotype distribution and the median joining network in breeds and plumage colour groups revealed a main haplotype (hap2) for tile-grey plumage. Hap2 is unique to the tile-grey feather of Piao chicken, and the individuals carrying this haplotype account for 62.96% of the whole tile-grey chicken.

4. The results of this study are of significance for further analysis of the molecular basis of tile-grey plumage and the selective breeding of tile-grey plumage.