How understanding plant body clocks could help transform how food is grown

Header image: Rimma Bondarenko/Shutterstock

Katharine Hubbard, University of Hull

Have you ever had a bad case of jet lag? That horrible feeling when you get off a long haul flight and your body is telling you it’s time to go to sleep, but the outside world is telling you it’s time for breakfast? That’s the biological effects of your inner body clock, also known as your circadian clock.

Plants, fungi and even some bacteria have a circadian rhythm too. Although plants don’t tend to hop onto international flights, any living organism with a circadian clock has the potential to get jet lagged. This is more than a fun fact: we could use this information to make crops more productive and tackle food security.

The first reports of an inner body clock in plants stretch back to ancient Greece, when a ship’s captain studied the daily opening and closing of leaves on a tamarind tree. The first systematic observations of plant circadian rhythms were conducted in the 1700s by the French scientist Jean-Jacques d’Ortous de Mairan who studied the rhythmic opening and closing of the leaves of Mimosa pudica (a plant in the pea family).

De Mairan noticed these cycles persisted even when the plant was in constant darkness. This demonstrated the leaf movements were not a response to changes in the lighting conditions, but were controlled by the plant itself. This is the definition of a circadian rhythm.

We now know these rhythms are controlled by a genetic network found inside each plant cell. About 20 genes control the circadian rhythm in plants. These genes switch each other on and off in a complicated circuit, generating a 24-hour rhythm.

This control circuit also activates other genes in the plant genome. Some genes are activated at dawn,