Effect of Elevated Levels of Carbon Dioxide on the Activity of RuBisCO and Crop Productivity

Abstract

Atmospheric CO2 concentration is now higher than it was at any time in the past 26 million years and is expected to nearly double during this century. This trend is of concern to agriculture because elevated atmospheric carbon dioxide levels have been shown to decrease the rates of photorespiration. Rubisco, the key enzyme in photosynthesis and photorespiration, exhibits dual activity and is known to be regulated by relative CO2/O2 ratio of the atmosphere. Terrestrial plants with a C3 photosynthetic pathway respond in the short term to increased CO2 concentration via increased net photosynthesis and decreased transpiration. Recent empirical evidence suggests that the warming may only be about 0.25 °C, so the primary effects on agriculture are likely to be the beneficial increases in crop yields and water use efficiency. However, researchers have shown that elevated levels of carbon dioxide inhibit nitrate assimilation in wheat and Arabidopsis plants. Another important implication of this study is the effect of elevated levels of carbon dioxide on the nutritional quality of the crop. Under elevated CO2 most plant species show higher rates of photosynthesis, increased growth, decreased water use, and lowered tissue concentrations of nitrogen and protein. Rising CO2 over the next century is likely to affect both agricultural production and food quality.