CIRCADIAN REGULATION OF PLANT GROWTH

Circadian clocks generate 24 h biological rhythms that provide an adaptive advantage to organisms from all kingdoms. A simplified clock model comprises three main components: an input (e.g. light and temperature) that resets the oscillation daily; a central oscillator where several loops are connected by the intertwining of chromatin remodelling, transcriptional, and post-translational mechanisms; and outputs including oscillating transcripts and/or proteins able to translate waving patterns into specific biological processes. Therefore, the clock maintains an anticipation mechanism controlling different aspects of the plant life cycle. From hypocotyl elongation (when seedlings grow through the soil reaching for light) to photosynthesis, stress responses and metabolism, the clock promotes plant fitness and an increase in biomass. Major developmental transitions are also under circadian regulation. Here, we will assess the impact of the circadian clock on plant growth (considering both elongation/expansion and biomass-driven growth). We will address the regulation of cell growth and proliferation, starch metabolism, and protein translation, focusing especially in plants but providing some insights in other organisms. We expect that these findings will allow a broader understanding of the relevance of circadian-regulated processes in providing organisms with the ability to adjust their growth and development to specific environmental conditions.