Nonsense mutation in PMEL is associated with yellowish plumage colour phenotype in Japanese quail

The L strain of Japanese quail exhibits a plumage phenotype that is light yellowish in colour. In this study, we identified a nonsense mutation in the premelanosome protein (PMEL) gene showing complete concordance with the yellowish plumage within a pedigree as well as across strains by genetic linkage analysis of an F₂ intercross population using approximately 2,000 single nucleotide polymorphisms (SNPs) that were detected by double digest restriction site-associated DNA sequencing (ddRAD-seq). The yellowish plumage was inherited in an autosomal recessive manner, and the causative mutation was located within an 810-kb genomic region of the LGE22C19W28_E50C23 linkage group (LGE22). This region contained the PMEL gene that is required for the normal melanosome morphogenesis and eumelanin deposition. A nonsense mutation that leads to a marked truncation of the deduced protein was found in PMEL of the mutant. The gene expression level of PMEL decreased substantially in the mutant. Genotypes at the site of the nonsense mutation were fully concordant with plumage colour phenotypes in 196 F₂ offspring. The nonsense mutation was not found in several quail strains with non-yellowish plumage. Thus, the yellowish plumage may be caused by the reduced eumelanin content in feathers because of the loss of PMEL function.