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COMBINED EFFECTS OF CO2 AND O3 ON ANTIOXIDATIVE AND PHOTOPROTECTIVE DEFENSE SYSTEMS IN NEEDLES OF PONDEROSA PINE
Citation:
Tausz, M., D M. Olszyk, S. Monschein, AND D T. Tingey. COMBINED EFFECTS OF CO2 AND O3 ON ANTIOXIDATIVE AND PHOTOPROTECTIVE DEFENSE SYSTEMS IN NEEDLES OF PONDEROSA PINE. Biologia Plantarum. Institute of Experimental Botany of the Academy of Sciences of the Czech Republic, Prague, Czech Republic, 48(4):543-548, (2004).
Description:
To determine interactive effects of important environmental stresses on biochemical defense mechanisms of tree seedlings, we studied responses to elevated O3 and elevated atmospheric CO2 on antioxidative and photoprotective systems in needles of ponderosa pine (Pinus ponderosa Dougl. ex Laws.). Ponderosa pine seedlings of a low O3 provenance were grown in experimental sun-lit mesocosm chambers under ambient air temperature and water vapour pressure deficit conditions for three years. Seedlings were exposed to either ambient or elevated CO2 (253 mol mol-1 above ambient), combined with low or elevated O3 (0.05 or 26.13 mol mol-1 @ hr, respectively) for the growing season prior to harvest of current year needles. Ozone exposure led to decreased needle chlorophyll a and b, the combined violaxanthin, antheraxanthin and zeaxanthin pigments; decreased ascorbate concentrations, and a more oxidized total ascorbate pool irrespective of the CO2 level. Trees under elevated CO2 had a more oxidized needle total glutathione pool. Glutathione concentrations, tocopherol, and carotenoid concentrations were not affected by treatments. There were no interactive effects between elevated CO2 and elevated O3 on any of the needle parameters. The results suggest that elevated atmospheric CO2 concentration does not compensate for ozone stress by increasing antioxidative capacity in ponderosa pine.