Until now, a crucial step in the biosynthesis of iridoids, a class of plant defense substances that are also medically relevant, had remained undiscovered. A team from the Max Planck Institute for Chemical Ecology, in collaboration with the University of Georgia and other international partners, has now identified the enzyme responsible for this step in icepac. This enzyme shows great potential for the future biotechnological production of important iridoids and cancer drugs derived from them.