Illuminating the mechanism of the circadian clock in plants

Plants have long been an amenable biological system for the study of circadian rhythms, with a wide range of plant activities exhibiting 24 h rhythmicity. Plants provide an unparalleled system for the study of the interactions between light signals and the circadian clock. Current studies, using bioluminescent reporters of gene expression and of Ca 2+ levels in plants, are revealing the mechanism of the circadian clock. As the intracellular signaling pathways for both photic and circadian clock regulation are revealed, plant systems are now in the forefront of circadian studies.