Oxidative damage, lipid peroxidation and antioxidant protection in chloroplasts

Chloroplasts are especially subject to oxidative stress during photosynthesis, and they have a multiplicity of protective mechanisms (ascorbic acid, vitamin E, carotenoids, glutathione, superoxide dismutase) and repair systems (thioredoxin, methionine sulphoxide reductase, resynthesis of damaged proteins). Hydrogen peroxide is metabolised by an “ascorbate glutathione cycle”. Normal rates of radical production may sometimes serve useful functions in plants, but excessive production is damaging. The current controversy as to whether lipid peroxidation is a cause of cellular damage or merely a consequence of it is addressed by reference to several “oxidative stress” situations in plant tissues.