Detoxification of xenobiotics by plants: Chemical modification and vacuolar compartmentation

Plants have versatile detoxification systems to counter the phytotoxicity of the wide variety of natural and synthetic chemicals - xenobiotics - present in the environment. One important detoxification mechanism is chemical modification of the xenobiotic by covalent linkage to the endogenous tripeptide, glutathione. The resulting glutathione conjugates are exported from the cytosol to the vacuole by an ATP-dependent tonoplast transporter. This detoxification pathway shares many features with the pathway used by plants for the synthesis and vacuolar deposition of secondary metabolites, such as anthocyanins. In addition, the vacuolar glutathione-conjuagate transporter shows functional similarities with an ATP-binding cassette transporter, the multidrug resistance-associated protein, present in drug-tolerant human cancer cells.