A Novel Mechanism that Regulates CO₂ Fixation in Plants

A team of researchers from the University of Essex has discovered a new mechanism that regulates carbon dioxide fixation in plants. Carbon dioxide fixation in plants is highly dependent on sunlight. Since the amount of sunlight varies during the day, plants must employ a mechanism that will allow them to vary the speed at which they capture carbon dioxide from the atmosphere. This will ensure the continuous production of important plant metabolites, especially sugars. Carbon dioxide is turned to sugars via a process called the Calvin Cycle.

The study showed for the first time how changing light environments influence the Calvin Cycle. Two important enzymes in the cycle, PRK and GAPDH, were found to stick together when light levels decrease. The darker it is, the more PRK and GADPH complex are formed, therefore the slower the Calvin Cycle. In conditions of high light, on the other hand, the enzyme complexes breakdown rapidly, speeding up the sugar-producing cycle.

The study increases scientists’ understanding of the CO2 fixation process, which may ultimately lead to the development of plants with increased biomass for food and fuel use.

The paper published by PNAS is available at http://www.pnas.org/cgi/content/abstract/0710518105v1