Plants set a ‘bedtime’ alarm to ensure their survival, a new study shows

Plants have a metabolic signal that adjusts their circadian clock at night to ensure they store enough energy to survive the night, a new study reveals.

The research – involving scientists at York University – suggests that this signal may provide the plant with important information about the amount of sugar available at dusk and therefore how to adjust the metabolism to last the night.

Plants use sunlight to make their own sugars from photosynthesis during the day and store them to provide energy during the night.

The ability to predict the sunrise and estimate the duration of the night, and adjust metabolism accordingly, is critical for plant survival and to maximize growth. This depends on a biological timer called a circadian clock, which is a network of oscillating genes that controls rhythms for about 24 hours.

Dr. Mike Haydon, a former biology department at York University and now based at the University of Melbourne, said: “We think this metabolic signal is acting like setting an alarm clock before going to sleep to ensure the plant’s survival.

“Plants must coordinate photosynthetic metabolism with the daily environment and adapt rhythmic physiology and development to match carbon availability.”

To understand how sugars change the circadian clock, the researchers measured gene expression in seedlings while modifying photosynthesis or sugar supply.

They discovered a set of genes regulated by the chemical compound superoxide, a molecule associated with metabolic activity. Most of these genes are active at night, including key genes that act on the circadian clock. They found that by inhibiting the production of superoxide, they also inhibited the effect of sugar on these genes in the circadian clock at night.

Professor Ian Graham of the Center for New Agricultural Products in the Department of Biology added: “Distinguishing the effects of light and sugars on photosynthetic cells is challenging. Our data suggest a new role for superoxide as a rhythmic signal related to sugar acting on at night and affects circadian gene expression and growth. “

The article, “Superoxide is promoted by sucrose and affects the amplitude of circadian rhythms at night”, was published in the magazine. PNAS.