October 24, 2013
Plants Tell Time With Sugar
redOrbit Staff & Wire Reports - Your Universe Online
Like animals, plants have a 24-hour internal clock, known as circadian rhythm, which allows them to innately maintain track of time. Now, researchers from the University of Cambridge’s Department of Plant Sciences are working to discover exactly how this process works.As Dr. Alex Webb and his colleagues explain in Wednesday’s edition of the journal Nature, weeds, trees, herbs, shrubs and other types of flora are able to anticipate sunlight and make the necessary adjustments to their biology. This internal clock is essential to flowering, fragrance emission, leaf movement and other biological processes, they added.
The key to plant circadian rhythms, Dr. Webb’s team has discovered, is sugar. Plants produce sugar during photosynthesis, and it is their way of converting energy from the sun into a chemical form that they can use to grow and function.
By monitoring seedlings growing in air that lacked carbon dioxide (in order to inhibit photosynthesis) and by growing and observing genetically modified plants, the researchers found that the production of sugar was linked to the regulation of genes that are responsible for a plant’s internal clock.
“Our research shows that sugar levels within a plant play a vital role in synchronizing circadian rhythms with its surrounding environment,” Dr. Webb explained in a statement. “Inhibiting photosynthesis, for example, slowed the plants internal clock by between two and three hours.”
The research, which was sponsored by the Biotechnology and Biological Sciences Research Council (BBSRC), also demonstrates that photosynthesis has a major impact on setting and maintaining robust circadian rhythms of Arabidopsis plants. This observation illustrates the essential role that metabolism plays when it comes to regulating the circadian clock.
“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 Dr. Mike Haydon, who worked with Dr. Webb on the project and is now with the University of York’s biology department.
“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,” he added. “This mirrors research that has previously shown that feeding times can influence the phase of peripheral clocks in animals.”
In addition Dr. Webb and Dr. Haydon, co-authors of the study included Olga Mielczarek and Dr. Katharine E. Hubbard of the University of Cambridge Department of Plant Sciences, and Fiona C. Robertson, now working in the University of Zimbabwe Department of Biochemistry.