Abstract: To investigate the molecular mechanism underlying feather coloration, 60 adult chickens (30 Qiangshan Cloud Chickens and 30 Fengwei Chickens, with equal sex distribution) were selected as experimental subjects. The polymorphisms of the SLC45A2 and TYR genes were analyzed by PCR amplification,sequencing,and insertion mutation detection methods. Results demonstrated that the missense mutation (c.1039 C>A, p.Leu347Met; homologous to the silver feather allele) in exon 4 of the SLC45A2 gene showed significant association with the cloud-like plumage phenotype (P<0.01), with mutant genotypes (homozygous mutant AA and heterozygous AW) accounting for 93% of Cloud Chickens. The 7.7 kb viral insertion mutation in intron 4 of the TYR gene was present in 18% of individuals (homozygous mutant CC genotype), but exhibited no significant effect on plumage coloration. The c.1039 C>A missense mutation in SLC45A2 gene exon 4 was the key genetic variant responsible for cloud-like plumage in Qiangshan Cloud Chickens. Although TYR gene participated in the melanin synthesis pathway, its intronic insertion mutation was not a determinant of feather color variation.

Key words: Qiangshan Cloud Chicken, SLC45A2, TYR, single nucleotide polymorphism (SNP)