PLANT PHYSIOLOGY , Vol 110, Issue 2 393-402, Copyright © 1996 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Responses of Antioxidative Systems to Drought Stress in Pendunculate Oak and Maritime Pine as Modulated by Elevated CO2
P. Schwanz, C. Picon, P. Vivin, E. Dreyer, J. M. Guehl and A. Polle
Albert-Ludwigs-Universitat Freiburg, Institut fur Forstbotanik und Baumphysiologie, Professur fur Baumphysiologie, Am Flughafen 17, D-79085 Freiburg, Germany (P.S., A.P.)
The aim of the present study was to investigate the effects of an enhanced
CO2 concentration alone or in combination with drought stress on
antioxidative systems of a deciduous (oak; Quercus robur) and an evergreen
(pine; Pinus pinaster) tree species. The seedlings were grown for one
season in a greenhouse in tunnels supplied with 350 or 700 [mu]L L-1 CO2.
The experiment was repeated in a second year. Antioxidants, protective
enzymes, soluble protein, and pigments showed considerable fluctuations in
different years. Elevated CO2 caused significant reductions in the
activities of superoxide dismutases in both oak and pine. The activities of
ascorbate peroxidase and catalase were also reduced in most cases. The
activities of dehydroascorbate reductase, monodehydroascorbate radical
reductase, glutathione reductase, and guaiacol peroxidase were affected
little or not at all by elevated CO2. When the trees were subjected to
drought stress by withholding water, the activities of antioxidative
enzymes decreased in leaves of pine and oak grown at ambient CO2 and
increased in plants grown at elevated CO2 concentrations. The present
results suggest that growth in elevated CO2 might reduce oxidative stress
to which leaf tissues are normally exposed and enhance metabolic
flexibility to encounter increased stress by increases in antioxidative
capacity.
