Pioneering findings on the dual role of carbon dioxide in photosynthesis

Researchers at Umeå University have found that carbon dioxide, in its ionic form bicarbonate, has a regulating function in the splitting of water in photosynthesis. This means that carbon dioxide has an additional role to being reduced to sugar. The pioneering work is published in the latest issue of the scientific journal PNAS. It is well known that inorganic carbon in the form of carbon dioxide, CO2, is reduced in a light driven process known as photosynthesis to organic compounds in the chloroplasts. Less well known is that inorganic carbon also affects the rate of the photosynthetic electron transport and thus the rate of photosynthetic oxygen production. This result was first published by the Nobel Prize winner Otto Warburg and his collaborator in the late 50s. Their explanation for the stimulating effect was logical at that time since they proposed that carbon dioxide was the source of the oxygen that plants produce.