News
Efficient use of water drives the evolution of photosynthetic systems
Published: 19 June 2014
Some species such as maize have a slightly different photosynthesis called C4, compared to the more common C3 type. An article in Journal of Experimental Botany states that the evolutionary steps from C3 to C4 photosynthesis are driven by low atmospheric carbon dioxide concentration, but the final steps really become advantageous when also water is scarce.
Most plant species adopt a so-called C3 photosynthetic system to fix carbon dioxide from the atmosphere in compounds used to grow new biomass. The C4 photosynthesis improves carbon dioxide fixation by using a biochemical ‘pump’ able to concentrate carbon dioxide and thus make the photosynthetic reactions more efficient.
Intermediate photosynthetic systems
Starting from C3 photosynthesis, evolution led to C4-plants through a series of small steps, nowadays apparent in a few plant species with intermediate photosynthetic systems that have features of both C3 and C4 types. These species offer a unique opportunity to study the evolutionary drivers of the C4 photosynthesis.
Use less water
Researchers thought that the most important evolutionary pressure for C4 photosynthesis was low atmospheric carbon dioxide, but recent evidence showed that also lack of water might have been important. Dr. Way and coworkers, including Giulia Vico (Department of Crop Production Ecology) and Stefano Manzoni (Department of Crop Production Ecology and Ecology) demonstrated that indeed moving from C3 to C4 plants involves a four-fold improvement of water use efficiency. In other words C4 plants and the intermediates most close to them, use much less water than C3 species to gain the same amount carbon.