How a cyanobacterial strain adapts to boost photosynthesis efficiency under various light conditions.
The Science:
Researchers sequence the genome of a cyanobacterial strain isolated from hot springs near Yellowstone National Park and conduct gene expression and metabolic studies to understand how it adapts to utilize far-red light to photosynthesize.
Fluorescence image of microcolonies of the Leptolyngbya sp. strain of cyanobacteria cells (JSC-1) collected from a hot spring near Yellowstone National Park. The image shows that the cells grow towards the light provided from above only. (Image courtesy of Bryant Lab)
The Impact:
Understanding how cyanobacteria utilize far-red light could help researchers introduce this capability to other plants, improving their growth rates. The work also provides researchers with a better understanding of how photosynthesis in cyanobacteria contributes to the global carbon cycle.
Summary
Marine cyanobacteria such as Prochlorococcus and Synechococcus are known to be responsible for more than a quarter of the net primary productivity in oceans, but terrestrial cyanobacteria also contribute significantly to global photosynthesis. In a study published ahead online August 21, 2014 in the Science Express edition of Science, a team led by Penn State University’s Don Bryant, a longtime collaborator of the U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science user facility, has found a strain of cyanobacteria in hot springs that utilizes wavelengths of sunlight that neither humans nor cyanobacteria can see to conduct photosynthesis. Known as JSC-1, the strain of Leptolyngbya cyanobacteria isolated from a floating microbial mat at LaDuke hot spring near Yellowstone National Park in Montana was sequenced as part of a DOE JGI Community Sequencing Program project.
To convert sunlight into energy-rich compounds, cyanobacteria primarily rely on three complexes known as Photosystem I (PS I), Photosystem II (PS II), and phycobilisomes (PBS). The team found that JSC-1 demonstrates what is called Complementary Chromatic Acclimation, in which the cyanobacteria changes color in response to the color of the light in order to maximize its photosynthetic yield. As part of the study, they grew JSC-1 under white fluorescent light, green-filtered fluorescent light, red-filtered fluorescent light, far-red light, and two wavelengths that simulate the solar irradiance reaching Earth’s surface. They found that when JSC-1 shifts from growing under white light to growing under far-red light, more than 40 percent of its genome responds by making changes to boost photosynthetic efficiency. Most of the core proteins of PS I and PS II are replaced, and there are structural changes to PBS core substructures. The team referred to this response as “Far-Red Light Photoacclimation” or FaRLiP.
“This enhanced photosynthetic performance in [far-red light] would be ecologically significant … for example, in mats, stromatolites, cyanobacterial blooms, or in the shade of plants,” the team reported. “FaRLiP should also benefit organisms living in sandy soils, because far-red light penetrates deeper than visible wavelengths…. Thus, FaRLiP could have a significant impact on cyanobacterial photosynthesis in soil crusts.”
Contact
Donald Bryant
Penn State University
dab14@psu.edu
Funding
- U.S. Department of Energy Office of Science
- National Science Foundation
Publication
Gan F et al. Extensive remodeling of a cyanobacterial photosynthetic apparatus in far-red light. Science. 2014 Aug 21. doi:10.1126/science.1256963 [Epub ahead of print]