Rapid Response of Antioxidant Enzymes to O3-Induced Oxidative Stress in Populus tremuloides Clones Varying in O3 Tolerance : International Journal of Forest Genetics

2000

S. 335-338

4 Abb., 27 Lit. Ang.

Unselbständiges Werk

200085147

The concentration of atmospheric ozone (O3), formed at the interaction of nitrogen oxides, volatile hydrocarbons and ultraviloet radiation, is increasing globally (Fowler et al. 1999) due to fossil fuel consumption. While O3 levels are increasing in the atmosphere, in fact none of it has been detected inside the leaf (Laisk et al. 1989). Ozone readily reacts with water giving rise to reactive oxygen species (ROS) hydrogen perioxide and superoxide anion radical (Grimes et al. 1983; Kanofsky & Sima 1995). ROS and especially radicals can non-specifically react with lipids, proteins and nucleic acids (Davies 1995) thus disrupting the structural and functional integrity of the cell. While the increased rise in tropospheric O3 and the resulting increase in ROS is the result of human activities, the active oxygen species are also produced naturally during the normal metabolism of photosynthesizing cells. All green plants as well as other aerobic organisms have evolved antioxidant defense systems to comat the inevitable ROS (Alscher et al. 1997). The antioxidant systems can be enzymatic or non-enzymatic ROS scavengers that require the activation of specific metabolic pathways and investment of energy.