Biosynthesis and antioxidant function of glutathione in plants

Glutathione is widely distributed in plant cells. It appears to be synthesized in both the chloroplast and the cytosol and to occur in both subcellular compartments at relatively high levels. Its function is that of an antioxidant; in concert with ascorbate, it acts to protect labile macromolecules against attack by scavenging free radicals and hydrogen peroxide, which are formed as a consequence of oxidative stresses such as extremes of temperature, drought, herbicides or air pollutants. An integral part of the response of glutathione metabolism to oxidative stress appears to include an increase in the levels of the reduced form of the molecule. The possible role of glutathione as an elicitor of transcriptional events associated with stress responses is briefly discussed.