The mechanism of and the defense against oxidative stress in higher plants.

Project Details


This project concerns the mechanism of the generation of, and the defense against oxidative stress in plants. We will continue our work with transgenic tobacco plants modified in catalase expression. Catalase-deficient and catalase-overproducing plants generate higher and lower fluxes of H2O2, respectively, than normal plants. In catalase-deficient plants, photorespiration causes H2O2-mediated damage. This allows one to determine under what stress conditions photorespiration plays an important role. Catalase-deficient plants will also be used for the study of (1) the role of H2O2 in the generation of oxidative damage; (2) the metabolic systems that are sensitive to oxidative damage; (3) the role of H2O2 as a signal molecule for the induction of antioxidant sytems; (4) the nature of the induced antioxidant systems. The latter two aspects will also be studied in catalase-overproducing plants. This work promises to lead to the discovery of an antioxidant function of systems in which such a function was hitherto not recognized.The research into the protection against oxidative stress in maize and tobacco will be continued. A. Tobacco: We will test catalase-underproducing plants, and glutathione peroxidase- overproducing plants, for oxidative stress tolerance. The stress will be will be applied in leaf discs, and especially at the level of the whole plant. Leaf discs will treated with methyl viologen or aminotriazole as described in the present and previous Annual Report. Whole plants will be exposed to elevated salt concentrations or low temperatures, and in hydroponic culture to K- or Mg deficiency. Stress tolerance will be determined from the stress-induced damage. Special attention will be paid to the recovery phase after cessation of the stress. We will investigate whether formation of hydrogen peroxide in leaves is a good measure of light-induced oxidative stress, both in leaf discs and at the whole plant level. B. Maize: The new MnSOD-overproducing lines will be tested for cold tolerance, by measurement of the growth rate. The FeSOD overproducing lines will first be tested for MV-tolerance, for comparison with MnSOD-overproducing lines, and then for cold tolerance. Hydrogen peroxide levels in plants grown at low temperatures will be determined as a measure of oxidative stress, if this proves to be a suitable test in tobacco
Effective start/end date1/01/9731/12/99

Flemish discipline codes

  • Biological sciences


  • Oxidative stress
  • Genetic Engineering
  • Photorespiration
  • Crop Improvement
  • Antioxidant