Evolution of benzoxazinone biosynthesis and indole production in maize.

The synthesis of a diverse spectrum of secondary metabolites has allowed plants to develop sophisticated chemical defense mechanisms. Maize (Zea mays L.), for example, releases a cocktail of volatile compounds when attacked by a caterpillar. These compounds attract a parasitic wasp, which deposits its eggs in the larvae, thereby controlling the population size of the herbivore. Indole, which is part of the cocktail, is produced by an enzyme recruited from primary metabolism. Indole can either function as a volatile signal or be converted by specific cytochrome P450 enzymes into benzoxazinoids, which function as important defense chemicals.