The observed diversification of (di)terpenoids in plants suggests that these natural products play important roles in such organisms. Chief among these are the gibberellin phytohormones, produced by both plants and associated microbes, and which have given rise to the particularly extensive super-family of labdane-related diterpenoids. To demonstrate the physiological relevance of these natural products, we have been investigating their role in plant-microbe interactions. Based on our extensive work on rice labdane-related diterpenoid metabolism, we have taken a reverse genetic approach to elucidate their role in the plant.