Czech J. Anim. Sci., 2026, 71(9):428-442 | DOI: 10.17221/9/2026-CJAS

Associations of SLC45A2 variation and MC1R/cAMP-related molecular characteristics with the “cloudy feather” phenotype in Qiangshan Cloud chickensOriginal Paper

Ronghong Li ORCID..., Min Xiao, Yuzhen Zhou, Xilamu Yi, Sang Mu

¹ Aba Prefecture Academy of Agricultural Sciences, Aba, Sichuan, P.R. China

Qiangshan Cloud chicken is a local chicken breed unique to Aba Prefecture, Sichuan Province, characterised by its distinctive “cloudy feather” phenotype, where black feathers form the base with attached cloud-like white feathers. This study aimed to evaluate genetic associations with this phenotype and to explore whether MC1R expression, cAMP concentration, melanogenesis-related transcript patterns, and qualitative histology were consistent with a multi-gene working model. The research was conducted in two phases. Phase I involved 220 adult chickens (110 Qiangshan Cloud chickens and 110 Fengwei chickens) for SLC45A2 and TYR genotyping and reciprocal crossing experiments. Phase II comprised the same 220 birds plus 30 recessive white-feathered chickens for MC1R genotyping. For qPCR and cAMP ELISA, 24 biologically independent birds were selected from each breed; qPCR was performed in three technical wells per bird and ELISA in two technical wells per bird, with the technical-well mean used as one biological observation. Histology included three independent birds per breed and three microscopic fields per bird and was evaluated qualitatively. In Phase I, genotyping and crossbreeding segregation results supported an association between the SLC45A2 c.1039C>A (Leu347Met) variant and the cloudy feather phenotype; 87 of 110 Qiangshan Cloud chickens (79.1%) carried an A-containing genotype, and the phenotypic segregation patterns in the crossbred offspring were consistent with sex-linked inheritance. The 7.7 kb insertion in TYR intron 4 was present in 20% of Qiangshan Cloud chickens, but no obvious feather-colour difference was detected between sampled cc and CC birds. The MC1R E allele frequency was 98.2% in Qiangshan Cloud chickens. MC1R expression and cAMP concentration were higher in Qiangshan Cloud chickens than in the comparison breeds (P < 0.01). MC1R and TYR expression were positively correlated in the Qiangshan Cloud wild-type subgroup (n = 18, r = 0.656, P = 0.003 1), whereas the mutant subgroup showed a nonsignificant inverse trend (n = 6, r = –0.710, P = 0.114). Positive correlations were also observed in Fengwei chickens (n = 24, r = 0.813, P = 1.35 × 10^–6) and recessive white-feathered chickens (n = 24, r = 0.616, P = 0.001 34). Representative histological sections qualitatively showed more extensive brown-black staining in Qiangshan Cloud chickens; melanin content was not quantified. The data support SLC45A2 c.1039C>A as a sex-linked candidate variant associated with cloud-like white-feather distribution. The high frequency of the MC1R E allele, higher MC1R expression and cAMP concentration, and the observed TYRP1 and DCT expression patterns are consistent with enhanced melanogenic signalling in Qiangshan Cloud chickens. However, direct negative regulation of TYR, functional compensation for the TYR insertion, and causal pathway relationships were not established and require functional validation. Because the comparisons involved genetically distinct breeds and MC1R was nearly fixed within Qiangshan Cloud chickens, the present design does not isolate an MC1R single-locus effect.

Keywords: cAMP signalling pathway; MC1R; multi-gene regulation; Qiangshan Cloud Chicken; SLC45A2; TYR

Received: January 20, 2026; Accepted: August 19, 2026; Published: September 29, 2026  Show citation