ASCORBATE AND GLUTATHIONE - KEEPING ACTIVE OXYGEN UNDER CONTROL

To cope with environmental fluctuations and to prevent invasion by pat hogens, plant metabolism must be flexible and dynamic. Active oxygen s pecies, whose formation is accelerated under stress conditions, must b e rapidly processed if oxidative damage is to be averted. The lifetime of active oxygen species within the cellular environment is determine d by the antioxidative system, which provides crucial protection again st oxidative damage. The antioxidative system comprises numerous enzym es and compounds of low molecular weight. While research into the form er has benefited greatly from advances in molecular technology, the pa thways by which the latter are synthesized have received comparatively little attention. The present review emphasizes the roles of ascorbat e and glutathione in plant metabolism and stress tolerance. We provide a detailed account of current knowledge of the biosynthesis, compartm entation, and transport of these two important antioxidants, with emph asis on the unique insights and advances gained by molecular explorati on.