Plants let chloroplasts know the time

March 14, 2013
Investigating the effect of different wavelengths of light. Image by Antony Dodd/University of Bristol

( —Plant cells communicate information about the time of day to their chloroplasts, the part of their cells that underpins all agricultural productivity on Earth, researchers at the University of Bristol have demonstrated in a study published today in Science.

Plant cells contain an internal clock (the ), which is able to regulate cellular processes so that they occur at the optimal time of day, causing a big increase in . As chloroplasts are the site of photosynthesis, their function is highly dependent on the daily changes in light environment.

It is thought that chloroplasts were originally free-living organisms that were incorporated into the cells of plants very early in plant evolutionary history. A result of this is that chloroplasts have retained some of the cellular machinery required to produce proteins from their own chloroplast DNA. An essential part of this machinery are 'sigma factors', and in present-day plants, they are encoded for by the cell's nuclear DNA.

The researchers were able to show that the production of sigma factors is controlled by the plant's clock. This enables the to regulate the activity of chloroplast genes, and ensure that the production of proteins essential for photosynthesis is co-ordinated with daylight.

Lead author, Dr Antony Dodd of Bristol's School of Biological Sciences said: "This is a major breakthrough that provides a completely new perspective on daily . We have learnt from this work that timing information moves between different parts of the cell, and in particular involves the chloroplast, which is the part of the cell that underpins all agricultural productivity on the planet. It's particularly fascinating that the process we identified makes use of genes that pre-date modern land plants and originates from the bacteria that gave rise to chloroplasts."

Explore further: New research alters concept of how circadian clock functions

More information: 'Circadian Control of Chloroplast Transcription by a Nuclear-Encoded Timing Signal' by Noordally, Z., Ishii, K., Atkins, K., Wetherill, S., Kusakina, J., Walton, E., Kato, M., Azuma, M., Tanaka, K., Hanaoka, M., and Dodd, AN. in Science:

Related Stories

Green plant transport mystery solved

January 26, 2010

Contrary to prevailing wisdom, a new study from plant biologists at UC Davis shows that proteins of the Hsp70 family do indeed chaperone proteins across the membranes of chloroplasts, just as they do for other cellular structures.

What makes a plant a plant?

June 15, 2011

Although scientists have been able to sequence the genomes of many organisms, they still lack a context for associating the proteins encoded in genes with specific biological processes. To better understand the genetics underlying ...

Recommended for you

Mapping the protein universe

October 9, 2015

To understand how life works, figure out the proteins first. DNA is the architect of life, but proteins are the workhorses. After proteins are built using DNA blueprints, they are constantly at work breaking down and building ...

ZomBee Watch helps scientists track honeybee killer

October 9, 2015

While scientists have documented cases of tiny flies infesting honeybees, causing the bees to lurch and stagger around like zombies before they die, researchers don't know the scope of the problem.

Gene editing: Research spurs debate over promise vs. ethics

October 9, 2015

The hottest tool in biology has scientists using words like revolutionary as they describe the long-term potential: wiping out certain mosquitoes that carry malaria, treating genetic diseases like sickle-cell, preventing ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Mar 16, 2013
The question for astrobiology is whether this circadian mechanism is necessary for life and if so can it be transmuted to other perhaps habitable exoplanets. The recent discovery of deeply buried hydrogen life forms under the oceanic crust would exhibit an alternative biological timing mechanism.
not rated yet Mar 16, 2013
As long as the timing is mutable. it should be OK. And remember, due to our Moon we have had a more varying daily rhythm than most planets, from an initial ~ 8 hours to today's 24 h. Though plants would have only seen the last 20 % change or so.

Modern organisms and cells have a lot of "necessary" mechanisms, by necessity of contingency creating so called "interlocking complexity" (Muller, 1930ish). Say, the nerve that loops down to the hearth before ending up controlling parts of our throat.

Some circadian clock mechanisms have deep ancestry, billions of years. Plenty of times for interlocking systems to form.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.