Picking out parallels: plant circadian clocks in context

Molecular models have been described for the circadian clocks of representa tives of several different Laxa. Much of the work on the plant circadian sy stem has been carried out using the thale cress, Arabidopsis thaliana. as a model. We discuss the roles of genes implicated in the plant circadian sys tem, with special emphasis on Arabidopsis. Plants have an endogenous clock that regulates many aspects of circadian and photoperiodic behaviour. Despi te the discovery of components that resemble those involved in the clocks o f animals or fungi, no coherent model of the plant clock has yet been propo sed. In this review, we aim to provide an overview of studies of the Arabid opsis circadian system. We shall compare these with results from different taxa and discuss them in the context of what is known about clocks in other organisms.