Isoprenoid biosynthesis. Metabolite profiling of peppermint oil gland secretory cells and application to herbicide target analysis

Two independent pathways operate in plants for the synthesis of isopentenyl diphosphate and dimethylallyl diphosphate, the central intermediates in th e biosynthesis of all isoprenoids. The mevalonate pathway is present in the cytosol, whereas the recently discovered mevalonate-independent pathway is localized to plastids. We have used isolated peppermint (Mentha piperita) oil gland secretory cells as an experimental model system to study the effe cts of the herbicides fosmido-mycin, phosphonothrixin, methyl viologen, ben zyl viologen, clomazone, 2-(dimethylamino)ethyl diphosphate, alendronate, a nd pamidronate on the pools of metabolites related to monoterpene biosynthe sis via the mevalonate-independent pathway. A newly developed isolation pro tocol for polar metabolites together with an improved separation and detect ion method based on liquid chromatography-mass spectrometry have allowed as sessment of the enzyme targets for a number of these herbicides.