Missing link in plants’ biological clock

15 March 2009


Scientists have found a missing link in the workings of the biological clocks of plants.

You might think that it is just animals that can detect light and respond to changes in night and day, but plants can too. And until now there has been a mystery surrounding how plants do this. Previously, scientists have studied the plant equivalent of laboratory mice - called Arabidopsis - and tracked down two primary feedback loops, one that detects the onset of light in the morning, and a second that senses when light fades in the evening. What was missing was a system to link the two together.

Now, Steve Kay and his team of researchers from the University of California, San Diego think they have found that missing link: a protein called CHE.

The presence of CHE was predicted nearly a decade ago, but only now has it been found.  What these researchers did was to hunt for proteins that bind to DNA and switch genes on or off. In particular they looked for proteins that changed in abundance over time, since those were the ones most likely to be involved in a plant's biological clock.

They found several cyclical proteins, but it was only CHE that stuck to the region of the plant DNA that is in charge of the ability to sense morning light levels. Taking a closer look the team also found that the same protein also binds to the region of DNA involved in the sensitivity to evening light levels dropping.

More and more evidence is piling up that biological clocks are crucial in controlling the growth of plants, and for things like timing flowering just right to ensure that flowers come out when it's not too cold still and when pollinating insects are flying around. Other studies have shown that altering the plants clocks can create crops that grow more vigorously, so if we can understand more about how those clocks work, crop scientists will one day develop crops that are even better.


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