Nav: Home

A new light protection mechanism discovered in plants

October 10, 2016

Scientists at Imperial College London have discovered a feedback mechanism at the heart of photosynthesis that protects plants from damage by light.

The researchers have discovered that the key enzyme in photosynthesis can tune its activity to avoid being damaged by light and oxygen.

Knowing how photosynthesis is regulated and protected could allow scientists to improve the process, potentially making agriculture and food production more efficient.

For example, understanding how this regulatory mechanism works could help researchers to identify the factors that are beneficial for plant growth and to define how to adjust these in order to optimise growth in controlled cultivation.

Photosystem II, the central enzyme in photosynthesis, uses solar energy to remove electrons from water. The electrons are used to fix carbon dioxide from the atmosphere, creating a form of carbon that constitutes the fuel and building blocks for life. Photosystem II changed the planet by putting most of the energy into the biosphere and all of the oxygen into the atmosphere.

When leaves close their pores to prevent water loss, this also prevents air exchange so that carbon dioxide cannot enter the system. As the carbon dioxide inside the leaf is used up, the electrons have nothing left to react with and so they build up.

Although carbon dioxide is not entering the system, light still is, generating excess electrons. As the electrons have nowhere to go, they instead engage in 'back-reactions' that form a 'killer molecule' called singlet oxygen. This killer molecule can damage the photosystem II enzyme.

Now, by using a technique called spectro-electrochemistry, researchers have discovered a mechanism that protects the enzyme from this damage. The trapped electrons trigger the release of a bicarbonate molecule from the enzyme, which was previously thought to be constantly bound to it.

The new study, published today in Proceedings of the National Academy of Sciences, shows that this bicarbonate release not only slows down the water-splitting reaction but crucially also protects the enzyme from light damage due to the harmful back-reactions.

Bicarbonate is formed when carbon dioxide dissolves in water, so its concentration is related to the amount of carbon dioxide in the local environment. As well as low carbon dioxide levels causing electrons to build up and trigger the release of bicarbonate, the study also suggests the possibility that the level of carbon dioxide itself in the local leaf environment could impact on the bicarbonate binding.

"This is such an intuitive feedback mechanism at the heart of biology that I think it will go into school textbooks," said lead author, Professor Bill Rutherford FRS from the Department of Life Sciences at Imperial.

"Now that we understand this new mechanism in the lab, the next step is to define when it kicks in out there in the field - not to mention the forest, greenhouse, plant pot, sea, lake and pond."

Dr Andrea Fantuzzi, co-lead author also from the Department of Life Sciences at Imperial, added: "The role of bicarbonate has long been a mystery. Otto Warburg, Nobel laureate, friend of Einstein and one of the twentieth century's leading biochemists, puzzled over this problem in the 1950s.

"Now the mystery is solved and a new regulatory mechanism defined. Not only is the question solved, but it could have real implications for understanding limitations to plant growth."

Imperial College London

Related Photosynthesis Articles:

Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.
Just how much does enhancing photosynthesis improve crop yield?
In the next two decades, crop yields need to increase dramatically to feed the growing global population.
Algal library lends insights into genes for photosynthesis
To identify genes involved in photosynthesis, researchers built a library containing thousands of single-celled algae, each with a different gene mutation.
New molecular blueprint advances our understanding of photosynthesis
Researchers at Lawrence Berkeley National Laboratory have used one of the most advanced microscopes in the world to reveal the structure of a large protein complex crucial to photosynthesis, the process by which plants convert sunlight into cellular energy.
How bacteria build hyper-efficient photosynthesis machines
Researchers facing a future with a larger population and more uncertain climate are looking for ways to improve crop yields, and they're looking to photosynthetic bacteria for engineering solutions.
More Photosynthesis News and Photosynthesis Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...