A group of researchers led by the Imperial College London had recently discovered a new type of photosynthesis which could rewrite our current biology textbooks, lead to new methods of engineering more efficient crops, and even change the way we hunt for extra-terrestrial life.
While the vast majority of life on Earth uses visible red light in the process of photosynthesis, the new type of virtually the same process uses near-infrared light instead. The discovery was made in a wide range of cyanobacteria (blue-green algae) found in shaded locations around the world.
Up until now, photosynthesis was considered to be the process whereby plants transform the green pigment, chlorophyll-a, into useful biochemicals by harnessing solar energy. This has also led to the concept of the ‘red limit’ which is used in astrobiology to determine the chances of discovering complex life on other planets.
Now, however, scientist have found that when cyanobacteria grow in near-infrared light, the standard chlorophyll-a systems shut down, which activates other systems reliant on a different type of chlorophyll, namely – chlorophyll-f, previously thought to merely harvest light.
Prior to the study, only one organism — the cyanobacterium called Acaryochloris — was known to do photosynthesis beyond the red limit, but since it was thought that photosynthesis under such conditions would lead to serious damage, the Acaryochloris was seen as an exception to the rule.
“This new form of photosynthesis made us rethink what we thought was possible. It also changes how we understand the key events at the heart of standard photosynthesis. This is textbook changing stuff,” said lead researcher Professor Bill Rutherford from the Department of Life Sciences at Imperial College London.
The researchers have found that ‘accessory’ chlorophylls previously thought to play only a minor part in the process actually performs the crucial step in the chemical chain-reaction, which holds true even for other types of photosynthesis.
“I did not expect that my interest in cyanobacteria and the diverse lifestyles would snowball into a major change in how we understand photosynthesis. It is amazing what is still out there in nature waiting to be discovered,” said senior author Dr Dennis Nürnberg.