Cyanogenic glucosides are widely distributed natural products in the plant kingdom and are found in important crop plants like sorghum, barley, cassava, clover, flax, lotus and almonds. Plants also contain degradative enzymes that upon cellular disruption of the plant tissue are brought in contact with the cyanogenic glucosides causing hydrogen cyanide release. This binary system - two sets of components which separately are chemically inert – provides cyanogenic plants with an immediate chemical defense response to herbivores and pathogens causing tissue damage. The biosynthetic pathway is catalyzed by two membrane bound cytochrome P450s and a soluble UDPG-glucosyltransferase and is highly channelled. The channeling mechanism is studied (collaboration with the Sligar laboratory, Urbana) by molecular modeling and by assembly of the metabolon into synthetic nano discs possessing the characteristics of a soluble protein. Biochemical knowledge of the pathway has enabled predicted metabolic engineering. The trait of cyanogenesis is about 430 million years old enabling co-evolution of cyanogenic plants and their herbivores and pests. The burnet moth Zygaena filipendulae is able to sequester the cyanogenic glucosides present in its host plant Lotus corniculatus as well as to de novo synthesize the compounds. We have demonstrated that these cyanogenic glucosides play intimate roles in the life cycle of the burnet moth e.g. as pheromone attractant, mating determinant, as nuptial gifts and in defense. Cyanogenic glucosides present in plant material used as green manure or left on the ground leaches into surface and ground water in amounts exceeding the EU and WHO approved threshold values for drinking water