Lateral Transfer of Genes from Fungi Underlies Carotenoid Production in Aphids

Pink for Me, Green for You Aphids come in different colors, a critical issue when fate is a question of pigmentation: Red aphids tend to be consumed by ladybugs and green ones by parasitic wasps. Aphid color is determined by carotenoids, the same group of chemicals that make flamingos pink. But unlike flamingos, which have to eat colored food to stay pink, aphids make their own pigment. Carotenoids are vital to animals, not only because of their decorative possibilities but also for their oxidation-protective qualities as visual pigments and immune-system modulators. On sifting through an aphid genome, Moran and Jarvik (p. 624 ; see the Perspective by Fukatsu ) discovered that the machinery for producing carotenoids has been acquired by an ancestral aphid in a lateral transfer event from a fungus. Although a spontaneous yellow mutant aphid was found that still possesses the sequence for biosynthesis of the red carotenoid pigment torulene, the sequence was discovered to have a single point mutation that puts a stop to turning red.