Genomic sequences for Tetranychus urticae wild-type and albino mutant strains

Most animals acquire carotenoids from their diets, as de novo synthesis of carotenoids is primarily limited to plants and some bacteria and fungi. Nevertheless, sequencing projects in aphids and adelgids, spider mites, and gall midges have identified genes with homology to fungal sequences encoding de novo carotenoid biosynthetic proteins. The relevance of these lateral gene transfers for the arthropods that acquired them has remained speculative, especially for spider mites that feed on plant cell contents, a rich source of carotenoids. Pigmentation in spider mites results solely from carotenoids. Using a combination of genetic approaches, including Illumina sequencing of wild-type and albino strains of the spider mite Tetranychus urticae, we show that variants in a single horizontally transferred phytoene desaturase result in complete albinism. Carotenoid biosynthetic genes of fungal origin have therefore enabled some mites to forgo dietary carotenoids, with endogenous synthesis underlying their intense pigmentation.