Expression levels of GSTA2 and APOD genes might be associated with carotenoid coloration in golden pheasant (Chrysolophus pictus) plumage

Carotenoids, which generate yellow, orange, and red colors, are crucial pigments in avian plumage. Investigations into genes associated with carotenoidbased coloration in avian species are important; however, such research is difficult because carotenoids cannot be synthetized in vertebrates as they are only derived from dietary sources. Here, the golden pheasant (Chrysolophus pictus) was used as a model in analysis of candidate gene expression profiles implicated in carotenoid binding and deposition. Using mass and Raman spectrometry to confirm the presence of carotenoids in golden pheasant feathers, we found C₄₀H₅₄O and C₄₀H₅₆O₂ in feathers with yellow to red colors, and in the rachis of iridescent feathers. The global gene expression profiles in golden pheasant skins were analyzed by RNA-seq and all six carotenoid binding candidate genes sequenced were studied by realtime PCR. StAR4, GSTA2, Scarb1, and APOD in feather follicles showed different expressions in red breast and orange nape feathers compared with that of iridescent mantle feathers. Further comparison of golden pheasant yellow rump and Lady Amherst's pheasant (Chrysolophus amherstiae) white nape feathers suggested that GSTA2 and APOD played a potential role in carotenoid-based coloration in golden pheasant.