Genome editing of thevermilionlocus generates a visible eye color marker forOncopeltus fasciatus

Abstract

AbstractInsects display a vast array of eye and body colors. Genes encoding products involved in biosynthesis and deposition of pigments are ideal genetic markers, contributing, for example, to the power ofDrosophilagenetics.Oncopeltus fasciatusis an emerging model for hemimetabolous insects, a member of the piercing-sucking feeding order Hemiptera, that includes pests and disease vectors. To identify candidate visible markers forO. fasciatus, we used parental and nymphal RNAi to identify genes that altered eye or body color while having no deleterious effects on viability. We selectedOf-vermilionfor CRISPR/Cas9 genome editing, generating three independent loss-of-function mutant lines. These studies mappedOf-vermilionto the X-chromosome, the first assignment of a gene to a chromosome in this species.Of-vermilionhomozygotes have bright red, rather than black, eyes and are fully viable and fertile. We used these mutants to verify a role forOf-xdh1, ortholog ofDrosophila rosy, in contributing to red pigmentation after RNAi. Rather than wild-type-like red bodies, bugs lacking bothvermilionandxdh1have bright yellow bodies, suggesting that ommochromes and pteridines contribute toO. fasciatusbody color. Our studies generated the first gene-based visible marker forO. fasciatusand expanded the genetic toolkit for this model system.