We could soon help plants grow faster to boost food security

Photosynthesis, notes a team of scientists at the University of Sheffield in the United Kingdom, “is the foundation of life on Earth providing the food, oxygen and energy that sustains the biosphere and human civilisation.”

It follows that understanding the process better can yield tangible benefits such as an ability to boost plant growth. The British researchers report that they have managed to unlock the structure of the protein complex dubbed cytochrome b6f, which influences plant growth during photosynthesis.

Cytochrome b6f provides the electrical connection between the so-called photosystem I and photosystem II reaction centers of oxygenic photosynthesis, which are two light-powered chlorophyll-proteins within the plant cell chloroplast that convert sunlight into chemical energy. The protein complex, the researchers say, serves as a sort of “proton battery” for storing energy.

“This stored energy can then be then used to make ATP, the energy currency of living cells. Ultimately this reaction provides the energy that plants need to turn carbon dioxide into the carbohydrates and biomass that sustain the global food chain,” explains Lorna Malone, a PhD student at the University of Sheffield’s Department of Molecular Biology and Biotechnology who was an author of a new study published in the journal Nature.

The protein complex cytochrome b6f, the scientists have discovered, also acts as a sensor that aids plants in their photosynthetic capacity in tandem with changes in their environments. The encoded response mechanism protects plants from damage when they need to endure adverse environmental conditions such as prolonged drought or too much sunlight.

“Cytochrome b6f is the beating heart of photosynthesis which plays a crucial role in regulating photosynthetic efficiency,” observes Matt Johnson, a biochemist at the University of Sheffield.

“Previous studies have shown that by manipulating the levels of this complex we can grow bigger and better plants,” he adds. “With the new insights we have obtained from our structure we can hope to rationally redesign photosynthesis in crop plants to achieve the higher yields we urgently need to sustain a projected global population of 9-10 billion by 2050.”