RNAi-Mediated Manipulation of Cuticle Coloration Genes in Knight (Hemiptera: Miridae).

Cuticle coloration in insects is a consequence of the accumulation of pigments in a species-specific pattern. Numerous genes are involved in regulating the underlying processes of melanization and sclerotization, and their manipulation can be used to create externally visible markers of successful gene editing. To clarify the roles for many of these genes and examine their suitability as phenotypic markers in Knight (western tarnished plant bug), transcriptomic data were screened for sequences exhibiting homology with the proteins. Complete open reading frames encoding putative homologs for six genes (, , , , , and ) were identified, with two variants for . Sequence and phylogenetic analyses supported preliminary annotations as cuticle pigmentation genes. In accord with observable difference in color patterning, expression varied for each gene by developmental stage, adult age, body part, and sex. Knockdown by injection of dsRNA for each gene produced varied effects in adults, ranging from the non-detectable (, ), to moderate decreases (, ) and increases (, ) in darkness, to extreme melanization (). Based solely on its expression profile and highly visible phenotype, appears to be the best marker for tracking transgenic .