In a plant's own sweet time: Sugar and circadian rhythms

Rotation of the Earth on its axis causes 24-h cycles in many features of the environment. Circadian rhythms generate a cellular measure of the time of day, providing a biological adaptation to daily changes in the environment. Plants need light to power photosynthesis in order to grow and reproduce, yet sunlight is only available for part of the 24-h day. It may therefore come as no surprise that circadian rhythms are extraordinarily important for plants. Experiments with the model plant Arabidopsis thaliana demonstrated that circadian rhythms increase plant productivity and photosynthesis1. Extension to other plant species is revealing how circadian rhythms are crucial for, and can be used to manipulate, agronomic traits of crops. Understanding and controlling the molecular bases for circadian regulation is therefore a crucial part of developing more productive crops for the next century.