Looks like we’ll have to come to terms with a new view about the basic mechanism of photosynthesis and to rewrite the textbooks on biology. Also, we may need to revise approaches to search for alien life and create more effective crops. The fact that scientists have discovered a new kind of photosynthesis. Work on this topic was published in Science on Friday, June 15. The vast majority of life on Earth uses visible red light in the photosynthesis process, however, the new type uses a near infrared light. They found a wide range of cyanobacteria (blue-green algae), which grow in the near-infrared light, in shaded conditions, the bacterial mats in Yellowstone and on the stone beaches in Australia.
As found by scientists at Imperial College London, this also happens in the closet with infrared LEDs.
Photosynthesis beyond the red limit
The usual, almost universal type of photosynthesis using the green pigment chlorophyll a, for collecting light, and to use its energy for the production of useful biochemical compounds and oxygen. Chlorophyll a absorbs light in such a way that only the energy of red light can be used for photosynthesis.
Since chlorophyll a is present in all plants, algae and cyanobacteria, which we know was considered that the energy of the red light sets the “red limit” for photosynthesis, in relation to the minimum amount of energy required to perform complex chemistry that produces oxygen. The red limit is used in astrobiology — according to it, scientists estimate, could complex life to evolve on planets in other solar systems.
However, when some of the cyanobacteria were grown under near infrared light, standard system, containing chlorophyll a, switched off and given space to operate other systems that contain another type of chlorophyll — chlorophyll f.
To this day, it was believed that chlorophyll f only collects light. A new study showed that in shaded conditions photosynthesis is included chlorophyll f using low-energy infrared light to complex chemical reactions. Photosynthesis is “beyond the red limit.”
Colony Chroococcidiopsis-like cells. Photosynthesis in the chlorophyll a occurs in the purple areas on chlorophyll f in yellow.
Lead author Professor bill Rutherford from the faculty of life Sciences at Imperial College says: “the New form of photosynthesis has forced us to rethink what we thought was standard. We also reviewed key developments in the heart of normal photosynthesis. Will have to rewrite the textbooks.”
Preventing light damage
The cyanobacterium Acaryochloris has long been known that carries out photosynthesis beyond the red limit. But since it only happens in one species with very specific habitat, it was considered an exception. Acaryochloris lives under the green marine ascidians and receives almost no light.
Photosynthesis based on chlorophyll f, which was reported last week, is a widespread third type of photosynthesis. However, it is only used in special shaded environment rich in infrared light in normal lighting conditions, use the normal red form of photosynthesis.
It was believed that light damage will be more serious beyond the red limit, but a new study has shown that this is not a problem for stable shaded conditions.
Andrea Fantuzzi, one of the authors, believes that “the discovery of a kind of photosynthesis that works beyond the red limit, changes our understanding of the energy requirements for photosynthesis. Sheds light on the use of light energy and mechanisms that protect the system against light damage”.
These findings will be useful for scientists who are trying to create a bio-engineered crops that can allow more efficient photosynthesis, using a wider range of wavelengths of light. Learn how these cyanobacteria protect themselves from damage caused by changes in the brightness of the light, we will be able to implement these mechanisms in conventional agricultural plants.
Dr. Dennis Nuremberg, the first author and initiator of the study, said: “I didn’t expect my interest in cyanobacteria and their diverse way of life will lead to significant changes in our understanding of photosynthesis. It’s amazing how much even just in nature awaiting discovery.”
A new view of photosynthesis
Ilya Hel