Photosynthesis, which allows energy from the sun to be converted into life-sustaining sugars, can also be hazardous to green plants. If they absorb too much sunlight, the extra energy destroys their tissue.
To combat this, green plants have developed a defense mechanism known as photoprotection, which allows them to dissipate the extra energy. Researchers from MIT and the University of Verona have now discovered how the key protein in this process allows moss and green algae to protect themselves from too much sun.
The researchers found that the protein, embedded in the membranes in the chloroplast, can switch between different states in response to changes in sunlight. When moss and green algae absorb more sunlight than they need, this protein releases the energy as heat, preventing it from building up and damaging the cells. The protein can act within seconds of a change in sun exposure, such as when the sun appears from behind a cloud.
“These photoprotective mechanisms have evolved from the fact that sunlight is not constant. There are sunny days; there are cloudy days. Clouds may briefly pass over, or the plant can be transiently in the shade,” says Gabriela Schlau-Cohen, an MIT assistant professor of chemistry and the senior author of the study.
Learning more about how this protein works could allow scientists to alter it in a way that would promote more photosynthesis, potentially increasing the biomass yield of both crops and algae grown for biofuels, Schlau-Cohen says.
MIT postdoc Toru Kondo is the lead author of the paper, which appears in the 17 July issue of Nature Chemistry. Other authors are MIT graduate student Wei Jia…