FoxO-mediated γ-carotene metabolism alters body coloration in Myzus persicae in response to starvation.

Body color transformations play important roles in the environmental adaptations of organisms. However, the molecular mechanisms and ecological significance underlying these phenomena remain unclear. In this study, we observed that starvation induced a shift in Myzus persicae body coloration from red to green. Through transcriptomic analyses, RNA interference (RNAi) assays, and dual-luciferase assays, we demonstrated that starvation down-regulates the expression of carotene desaturase 2 (Cde2), a key gene involved in the dehydrogenation of γ-carotene, through the nutrient-responsive transcription factor FoxO, ultimately leading to a color transition in M. persicae. Metabolomic analyses further revealed that starvation enhances the cyclization of γ-carotene and the metabolism of β-carotene, which is a γ-carotene cyclization product. This metabolic change strengthens aphids' behavioral preference for yellow cues, which facilitates aphid-located host plants to combat starvation stress. Overall, these results provide new insights into the mechanisms underlying body color plasticity and environmental adaptation strategies in insects.