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Lutein Added a Pigmentary Component to Peafowl Iridescent Coloration

Close-up of an iridescent Indian peafowl feather
Research · Molecular biology & biochemistry

A biochemical and transcriptomic study of male Indian peafowl (Pavo cristatus) and green peafowl (Pavo muticus) found that their iridescent feather colors are not produced by structural coloration alone. Structural color arises when microscopic arrangements of melanin, keratin and air alter how light is reflected, rather than from pigment alone. The researchers detected the xanthophyll carotenoid lutein in all analysed feather samples and found differences in the expression of genes associated with melanin and carotenoid deposition between iridescent and non-iridescent feather follicles.

Feathers and feather follicles were sampled from three adult males of each species. Indian peafowl came from Beijing Agricultural College and green peafowl from Qinhuangdao Wildlife Park. Samples were collected from the rump, mantle and breast, while the eyespots of train feathers were further separated into green, brown, blue and purple regions.

Peafowl feather regions and lutein measurements in Indian and green peafowl
Sampled feather regions and xanthophyll lutein concentrations in Indian and green peafowl. Figure 1 from Wang et al. (2026), Animals, CC BY 4.0.

Colored feathers contained more lutein than breast feathers

Lutein concentrations ranged from 0.0082 to 0.021 µg/g. In both species, colored rump and mantle feathers contained significantly more lutein than non-iridescent breast feathers. In Indian peafowl, train feathers had about twice the lutein concentration of breast feathers, and the blue region of the eyespot contained the highest concentration among the four eyespot colors.

ASIP and GSTA2 expression differed between iridescent and breast follicles

Transcriptome analysis — a comparison of which genes were active in the feather follicles — showed markedly lower expression of the melanin-regulating gene ASIP in rump follicles than in breast follicles. ASIP expression in rump follicles was less than one-thirtieth of the breast level in Indian peafowl and less than one-twelfth in green peafowl, a pattern consistent with greater eumelanin deposition in the iridescent regions. The carotenoid-deposition-related gene GSTA2 was expressed more strongly in rump follicles; in green peafowl, expression was about three times the breast level. The authors interpret the results as evidence that ordered melanin-based nanostructures provide the physical foundation for iridescence, while lutein acts as a pigmentary filter that absorbs particular wavelengths and helps fine-tune the final hue.

Sources and image credit

  1. Wang, G., Zhang, X., Zhao, X., Ren, X., Ning, Z., & Qu, L. (2026). Structural coloration and carotenoids together create the vibrant colors of peafowl feathers. Animals, 16(6), 903. https://doi.org/10.3390/ani16060903Primary open-access research article published 13 March 2026 under CC BY 4.0. Feather and follicle samples from three adult male Indian peafowl and three adult male green peafowl were analysed by UHPLC-MS/MS and transcriptomics. Lutein was detected in all feather samples at 0.0082–0.021 µg/g and was more abundant in colored than non-iridescent feathers; ASIP and GSTA2 expression differed between feather-follicle regions.

Image: Mroede — iridescent feather from an Indian Peafowl (Pavo cristatus), photographed 31 July 2008; location not specified by the source; Wikimedia Commons; representative feather image, not one of the samples analysed in the study · CC BY 3.0 · Source

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Molecular biology & biochemistry

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