Plants Maintain Internal Clock using Sugars

New botanical research from the University of Cambridge suggests that plants use internal sugars to determine the time of day.

Just like humans, plants have an internal clock known as the circadian rhythm. And just like us, plants use the circadian rhythm to establish the time of day, even when there is no sunlight. For plants that means when the sun rises in the morning, the plant does not simply respond to the stimulus, but rather it reacts to it, having made preparations for a sunrise it knew was coming all along.

"This ability to keep time provides an important competitive advantage and is vital in biological processes such as flowering, fragrance emission and leaf movement," researchers from the University of Cambridge Department of Plant Sciences said in a statement.

The researchers have found the sugars are key to a plant's internal time-keeping ability.

"Our research shows that sugar levels within a plant play a vital role in synchronizing circadian rhythms with its surrounding environment. Inhibiting photosynthesis, for example, slowed the plants internal clock by between 2 and 3 hours," said lead study author Alex Webb.

Webb said the find indicates that photosynthesis has a profound effect on setting and maintaining a circadian rhythm in Arabidopsis plants, small flowering plants indigenous to Europe that are related to cabbage and mustard.

Furthermore, the researchers explained, the find demonstrates the critical role metabolism plays in regulating the circadian rhythm.

"The accumulation of sugar within the plant provides a kind of feedback for the circadian cycle in plants -- a bit like resetting a stopwatch," said Mike Haydon, who performed much of the research at Cambridge and is now at the University of York.

"We think this might be a way of telling the plant that energy in the form of sugars is available to perform important metabolic tasks. This mirrors research that has previously shown that feeding times can influence the phase of peripheral clocks in animals."

Webb and Haydon's research is published in the journal Nature.