How Plants' Light-Sensitive 'Eyes' Tell Whether It's Night or Day

Why do plants turn toward the sun and how do they do it? It has everything to do with light-sensitive proteins within plant cells. Now, scientists have taken a closer look at these proteins and have discovered exactly how they change when they discover light.

The proteins are part of the "phytochrome" family, and can be found in all plant leaves. The proteins detect the presence of light and then inform the cell whether it's night or day, or whether the plant is in the shade or the sun.

"You can think of them as the plant's 'eyes,'" said Sebastian Westenhoff, one of the researchers, in a news release. "Our study has shown how these eyes work at the molecular level."

In order to examine these proteins a bit more closely, the researcher used laser light to initiate the structural change. They then used X-rays to image the change. More specifically, they looked at this structural change from bacteria, since it's possible to obtain sufficient material to work on from bacteria.

"We already knew that some form of structural change was taking place, since the light signals must be transferred onwards to the cell," said Westenhoff in a news release. "What we didn't know, however, was how the structure changed, and this is what we have revealed. Nearly the complete molecule is rebuilt."

The findings reveal how phytochromes work within plants. This could lead to new strategies when it comes to developing more efficient crops-something that will be crucial in a future where climate change will hinder crop production.

"Proteins are the factories and machines of life, and their structures change when they carry out their specific tasks," said Westenhoff in a news release. "At the moment, it's usually not possible to determine these changes. But I believe that we can use similar experiments to determine many important structural changes in phytochromes and other proteins."

The findings are published in the journal Nature.