TEMPORAL CONTROL OF PLANT-ENVIRONMENT INTERACTIONS BY THE CIRCADIAN CLOCK

The rotation of the earth generates dramatic daily and seasonal variation in the terrestrial environment. Plants, like other organisms, have evolved an endogenous biological oscillator to predict these daily changes in light and temperature and adjust to shifting seasonal conditions. This system must be robust to unexpected environmental challenges but can also assist plants to adjust physiology accordingly. Key features of the circadian system that contribute to achieve these are the process of entrainment, by which external cues adjust the state of the oscillator, and gating, by which the sensitivity to a stimulus is modified according to the time of day. In this way, the circadian clock is a dynamic hub which integrates physiology, metabolism, and growth in the context of a plant's current environment. We provide a comprehensive summary of the molecular composition of the core oscillator in Arabidopsis and the mechanisms of entrainment and gating. In particular, we focus on phytohormone signalling, photosynthetic metabolism, and defence responses as examples of core plant responses to environment that are integrated within the circadian system