A molecular mechanism for bright color variation in parrots
Roberto Arbore, Soraia Barbosa, Jindřich Brejcha, Yohey Ogawa, Yu Liu, Michaël P. J. Nicolaï, Paulo Pereira, Stephen J. Sabatino, Alison Cloutier, Emily Shui Kei Poon, Cristiana I. Marques, Pedro Andrade, Gerben Debruyn, Sandra Afonso, Rita Afonso, Shatadru Ghosh Roy, Uri Abdu, Ricardo J. Lopes, Peter Mojzeš, Petr Maršík, Simon Yung Wa Sin, Michael A. White, Pedro M. Araújo, Joseph C. Corbo, Miguel Carneiro
Abstract
Parrots produce stunning plumage colors through unique pigments called psittacofulvins. However, the mechanism underlying their ability to generate a spectrum of vibrant yellows, reds, and greens remains enigmatic. We uncover a unifying chemical basis for a wide range of parrot plumage colors, which result from the selective deposition of red aldehyde- and yellow carboxyl-containing psittacofulvin molecules in developing feathers. Through genetic mapping, biochemical assays, and single-cell genomics, we identified a critical player in this process, the aldehyde dehydrogenase ALDH3A2 , which oxidizes aldehyde psittacofulvins into carboxyl forms in late-differentiating keratinocytes during feather development. The simplicity of the underlying molecular mechanism, in which a single enzyme influences the balance of red and yellow pigments, offers an explanation for the exceptional evolutionary lability of parrot coloration.