Investigating the mode of action of natural phytotoxins

The potential use of natural phytotoxins (including allelochemicals) to develop novel tools for weed management is enhanced by the elucidation of their modes of action. This approach has not been emphasized by the agrochemical industry, although the possibility of discovering new target sites may be promising, since natural products tend to have modes of action different from synthetic herbicides. The approach of testing a compound on all known herbicide molecular target sites for commercial herbicides and other potent phytotoxins is feasible. However, this would preclude the discovery of new mechanisms of action. Discovering new target sites requires more challenging holistic approaches, initiated with physiological and biochemical studies that use whole plant assays. Studying basic plant responses to a compound may yield important clues to the specific physiological processes affected by the compounds and uncover novel mechanisms of action.