Plants use ‘bedtime alarm clock’ that helps them stay alive overnight

YORK, England — Here’s some research that may give new meaning to the term “flower bed.” Plants, it turns out, have their own “bedtime alarm clock” that helps them survive the night, reveals a new study.

Researchers at the University of York have discovered that plants possess an internal signal which they believe tells them the amount of sugar they has in their systems at dusk. Plants use sunlight to make their own sugars from photosynthesis during the day and store them to provide energy during the night.

Being able to predict sunrise and estimate the length of the night, as well as fine-tune metabolism depends on a biological time-keeper called a circadian clock. This is a network of genes which drives rhythms of roughly 24 hours.

Biologists think this signal, or so-called “alarm,” gives plants the information they need to adjust their metabolism in the dark nighttime hours to stay alive.

Arabidopsis clock in plants
Watching the Arabidopsis clock: Seedlings expressing a light emitting firefly gene controlled by the plant’s circadian rhythm. (Credit: University of York)

“We think this metabolic signal is acting rather like setting an alarm clock before bedtime to ensure the plant’s survival,” explains Dr. Mike Haydon, formerly from the university’s department of biology, in a statement.  “Plants must coordinate photosynthetic metabolism with the daily environment and adapt rhythmic physiology and development to match carbon availability.”

Haydon and his colleagues discovered a set of genes regulated by the chemical compound superoxide, which is associated with metabolic activity. Most of these genes are active in the evening, including key genes that act in the circadian clock.

The researchers found by halting the production of superoxide, they also stopped the effect of sugar on these circadian clock genes in the evening, revealing the plants’ so-called “alarm.”

“Distinguishing the effects of light and sugars in photosynthetic cells is challenging. Our data suggest a new role for superoxide as a rhythmic sugar-related signal which acts in the evening and affects circadian gene expression and growth,” adds Ian Graham, a professor from the Department of Biology’s Centre for Novel Agricultural Products.

The findings are published in the journal PNAS.

SWNS writer William Janes contributed to this report.