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Interactive Effects of Elevated CO2 and Growth Temperature on the Tolerance of Photosynthesis to Acute Heat Stress in C3 and C4 Species

Interactive Effects of Elevated CO2 and Growth Temperature on the Tolerance of Photosynthesis to Acute Heat Stress in C3 and C4 Species,E. William Ham

Interactive Effects of Elevated CO2 and Growth Temperature on the Tolerance of Photosynthesis to Acute Heat Stress in C3 and C4 Species   (Citations: 2)
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Determining effects of elevated CO2 on the tolerance of photosynthesis to acute heat-stress (heat wave) is necessary for predicting plant responses to global warming, as photosynthesis is thermolabile and acute heat-stress and atmospheric CO2 will increase in the future. Few studies have examined this, and past results are variable, which may be due to methodological variation. To address this, we grew two C3 and two C4 species at current or elevated CO2 and three different growth temperatures (GT). We assessed photosynthetic thermotolerance in both unacclimated (basal tolerance) and pre- heat-stressed (preHS =acclimated) plants. In C3 species, basal thermotolerance of net photosynthesis (Pn) was increased in high CO2, but in C4 species, Pn thermotlerance was decreased by high CO2 (except Zea mays at low GT); CO2 effects in preHS plants were mostly small or absent, though high CO2 was detrimental in one C3 and one C4 species at warmer GT. Though high CO2 generally decreased stomatal conductance, decreases in Pn during heat stress were mostly due to non-stomatal effects. Photosystem II (PSII) efficiency was often decreased by high CO2 during heat stress, especially at high GT; CO2 effects on post-PSII electron transport were variable. Thus, high CO2 often affected photosynthetic theromotolerance, and the effects varied with photosynthetic pathway, growth temperature, and acclimation state. Most importantly, in heat-stressed plants at normal or warmer growth temperatures, high CO2 may often decrease, or not benefit as expected, tolerance of photosynthesis to acute heat stress. Therefore, interactive effects of elevated CO2 and warmer growth temperatures on acute heat tolerance may contribute to future changes in plant productivity, distribution, and diversity.
Published in 2008.
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    • ...cate that elevated CO2 will benefit photosynthesis during heat stress in C3 and CAM plants grown at near-optimal temperatures, but that high CO2 will often decrease photosynthesis during heat stress in C4 plants at both near-optimal and supraoptimal growth temperatures and CAM plants at supra-optimal growth temperatures (Hamilton et al. 2008; Wang et al. 2008)...

    Sasmita Mishraet al. Interactive Effects of Elevated CO2 and Ozone on Leaf Thermotolerance ...

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