Edinburgh, Scotland, United Kingdom - TAIR

The circadian clock controls carbohydrate
metabolism and hence growth rate in
Arabidopsis plants at night
Using the model plant Arabidopsis, we have revealed the mechanism by which
the circadian clock optimises plant growth and productivity. We show that the
circadian clock has a central and previously unreported function in controlling
carbohydrate availability in leaves at night. Signals from the clock set the rate of
starch mobilisation to available sugars, so that plants are depleted of starch
precisely at the anticipated dawn. This timing is vital for the normal growth of the
plant: if starch reserves are exhausted before dawn there is a massive
transcriptional “starvation response” and growth stops.
By utilizing a combination of abnormal photoperiods, mutants defective in central
elements of the circadian clock and mutants defective in conversion of starch to
sugars we demonstrate unambiguously that 1) the rate of conversion of starch
to sugars in leaves at night is set by the circadian clock and 2) failure to set the
correct rate leads directly to reductions in plant growth rate.
Our results provide a new and unexpected perspective on the function of the
plant circadian clock, and are relevant to circadian biology in general. They also
have important implications for understanding plant productivity.
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C04
Wednesday 14:45 -15:00
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Alexander Graf1
Armin Schlereth2
Mark Stitt2
Alison Smith1
1John Innes Centre
Norwich
UK
2Max Planck Institute of
Molecular Plant Physiology
Golm
Germany