Plants have a metabolic signal that adjusts their circadian clock in the
evening to ensure they store enough energy to survive the night, a new study
reveals.
The research—involving scientists from the University of York—suggests this
signal might provide important information to the plant about the amount of
sugar available at dusk and therefore how to adjust 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 sunrise and estimate the duration of the night, and
fine-tune metabolism accordingly, is critical for plant survival and to
maximize growth. This depends on a biological time-keeper called a circadian
clock which is an oscillating gene network which drives rhythms of about 24
hours.
Dr. Mike Haydon, formerly from the Department of Biology, University of York
and now based at the University of Melbourne said: "We think this metabolic
signal is acting rather like setting an alarm clock before bedtime 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 alter the circadian clock, the researchers measured
gene expression in seedlings while modifying photosynthesis or sugar supply.
They discovered a set of genes known to be regulated by the chemical
compound, superoxide, a molecule associated with metabolic activity. Most of
these genes are active in the evening, including key genes that act in the
circadian clock. They found by inhibiting the production of superoxide, they
also inhibited the effect of sugar on these circadian clock genes in the
evening.
Professor Ian Graham from the Department of Biology's Centre for Novel
Agricultural Products added: "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."
The paper, "Superoxide is promoted by sucrose and affects amplitude of
circadian rhythms in the evening," is published in the journal, PNAS.
Reference:
Superoxide is promoted by sucrose and affects amplitude of circadian rhythms
in the evening, PNAS (2021).
Tags:
Plants & Animals