Coordinated activation of the metabolic pathways induced by LED blue light in citrus fruit

•Light emitting diodes blue light (LBL) represses iron homeostasis in citrus fruit.•LBL activates photooxidative repair-related responses and carbohydrate metabolism.•LBL increases total flavonoids and represses the limonene catabolism.•LBL favors lipid metabolism toward the synthesis of pigments and oxylipins.•Shifting from LBL to darkness favors ferrochelatase, steroid and alkaloid metabolism. The biochemical changes induced by LED Blue Light (LBL) (450 nm) in Lane Late oranges were investigated. The selected quantum flux (60 µmol m−2 s−1, 2 days) was associated with resistance against Penicillium digitatum, the main postharvest pathogen of citrus fruit. A holistic overview was obtained by a comparative transcriptome profile analysis, which revealed that LBL favored energy metabolism and redirected metabolic pathways toward the synthesis of diverse primary and secondary metabolism products. LBL favored reactive oxygen species homeostasis and metabolic activities involving lipid metabolism, specifically the synthesis of pigments and oxylipins, and the metabolism of carbohydrates, amino acids and indol- and alkaloid-derivatives. LBL also repressed limonene catabolism and triggered phenylpropanoid derivatives-related changes, which increased content in total flavonoids. Transferring fruit from LBL to darkness favored those processes involving amino acids, different phenylpropanoid, alkaloid and terpenoid classes, and ferrochelatase activity.