Genetic Basis of Keto-Carotenoid Production in Spider Mites

ß-carotene and keto-carotenoid derivatives determine the body and eye coloration of spider mites (Arthropoda: Chelicerata). Here, we focus on a carotenoid pigment mutant of the spider mite Tetranychus kanzawai that lost the ability to produce keto-carotenoids. We employed bulked segregant analysis and localized the causal locus to a single narrow genomic region. The causal mutation was fine-mapped to a minimal candidate region that held only one complete gene, the cytochrome P450 monooxygenase CYP384A1, of the CYP3 clan. Using a number of genomic approaches, we revealed that an inactivating deletion in the fourth exon of CYP384A1 caused the aberrant pigmentation. Phylogenetic analysis indicated that CYP384A1 is orthologous across mite species of the ancient Trombidiformes order where keto-carotenoids typify eye and body coloration, suggesting a deeply conserved function of CYP384A1 as a carotenoid ketolase.