CHROMIUM-INDUCED OXIDATIVE STRESS IN PEA CHLOROPLASTS

摘要

In plant cells, chloroplasts, mitochondria and peroxisomes are important intracellular generators of reactive oxygen species (ROS) like superoxide radical (O_2~(·-)) and hydrogen peroxide (H2O2) (Salin, 1991). In chloroplasts, O_2~(·-) and O_2~(·-)-derived hydrogen peroxide are mainly produced by electron acceptor of photosystem I (Asada and Takahashi, 1987). In addition O2_2~(·-), if not scavenged quickly, can participate in the formation of lethal hydroxyl radicals (·OH). These ROS are highly reactive and, in the absence of any protective mechanism, can damage different aspects of cell structure and function. Oxidative damage to chloroplasts may be minimized by the enzymes of the ascorbate-glutathione cycle and various anti-oxidants.