PLANT PHYSIOLOGY , Vol 109, Issue 2 421-432, Copyright © 1995 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Amelioration of Ozone-Induced Oxidative Damage in Wheat Plants Grown under High Carbon Dioxide (Role of Antioxidant Enzymes)
M. V. Rao, B. A. Hale and D. P. Ormrod
Department of Horticultural Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
O3-induced changes in growth, oxidative damage to protein, and specific
activities of certain antioxidant enzymes were investigated in wheat plants
(Triticum aestivum L. cv Roblin) grown under ambient or high CO2. High CO2
enhanced shoot biomass of wheat plants, whereas O3 exposure decreased shoot
biomass. The shoot biomass was relatively unaffected in plants grown under
a combination of high CO2 and O3. O3 exposure under ambient CO2 decreased
photosynthetic pigments, soluble proteins, and ribulose-1,5-bisphosphate
carboxylase/oxygenase protein and enhanced oxidative damage to proteins,
but these effects were not observed in plants exposed to O3 under high CO2.
O3 exposure initially enhanced the specific activities of superoxide
dismutase, peroxidase, glutathione reductase, and ascorbate peroxidase
irrespective of growth in ambient or high CO2. However, the specific
activities decreased in plants with prolonged exposure to O3 under ambient
CO2 but not in plants exposed to O3 under high CO2. Native gels revealed
preferential changes in the isoform composition of superoxide dismutase,
peroxidases, and ascorbate peroxidase of plants grown under a combination
of high CO2 and O3. Furthermore, growth under high CO2 and O3 led to the
synthesis of one new isoform of glutathione reductase. This could explain
why plants grown under a combination of high CO2 and O3 are capable of
resisting O3-induced damage to growth and proteins compared to plants
exposed to O3 under ambient CO2.
