|By Lliane Hunter | 2 years ago|
Scientists have discovered a new type of chlorophyll that pushes the boundaries of plants’ ability to photosynthesise, reports Mike McRae for Science Alert.
Briefly, organisms like plants and cyanobacteria mix carbon dioxide with water and use sunlight to construct glucose—their source of food. To convert photons into chemical bonds requires the use of a protein called chlorophyll-a, which soaks up mostly red wavelengths of light while reflecting the greens, blues, and purples, McRae explains. For some time, scientists assumed that only about 700 nanometers of the red part of the spectrum was worth collecting because anything longer would require more sensitive photosystems, and risk damage. Thus, chlorophyll-a is found in virtually everything that photosynthesises.
However, writes McCrae, in 2013 a cyanobacterium called Acaryochloris marina was found to possess a type of chlorophyll labeled ‘d’ that absorbed wavelengths 40 nanometers longer than type a. An exciting discovery, but Acaryochloris marina is fairly niche—living in the shade of sea squirts—so, the search for more examples continued. Now, after conducting experiments on the extremophile cyanobacterium Chroococcidiopsis thermalis, researchers have found their answer. When placed in the shade and fed only infrared, a newly discovered type of chlorophyll—type ‘f’—runs the show. Chlorophyll-f extends the size of wavelengths an organism can absorb to over 760 nanometers, close to infrared. “The new form of photosynthesis made us rethink what we thought was possible,” says senior researcher Bill Rutherford from Imperial College London.
Chlorophyll-f can switch between absorbing low energy wavelengths longer than 760 nanometers to slightly more intense light closer to 727 nanometers. The belief is that this discovery can help produce hardier plants in the future capable of making better use of variable light conditions. What’s more, developers may be able to design oxygen-generating algae and bacteria that can adapt to different wavelengths of light, and assist in terraforming Mars.