A MECHANISM FOR INDUCING PLANT DEVELOPMENT - THE GENESIS OF A SPECIFIC INHIBITOR

Parasitic strategies are widely distributed in the plant kingdom and f requently involve coupling parasite organogenesis with cues from the h ost. In Striga asiatica, for example, the cues that initiate the devel opment of the host attachment organ, the haustorium, originate in the host and trigger the transition from vegetative to parasitic mode in t he root meristem. This system therefore offers a unique opportunity to study the signals and mechanisms that control plant cell morphogenesi s. Here we establish that the biological activity of structural analog s of the natural inducer displays a marked dependence on redox potenti al and suggest the existence of a semiquinone intermediate. Building o n chemistry that exploits the energetics of such an intermediate, cycl opropyl-p-benzoquinone (CPBQ) is shown to be a specific inhibitor of h austorial development. These data are consistent with a model where ha ustorial development is initiated by the completion of a redox circuit .