Four easy pieces: mechanisms underlying circadian regulation of growth and development

Authors: THINES, BRYAN - University Of California; Harmon, Frank

Submitted to: Current Opinion in Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2010
Publication Date: 10/11/2010
Citation: Thines, B., Harmon, F.G. 2010. Four easy pieces: mechanisms underlying circadian regulation of growth and development. Current Opinion in Plant Biology. 14:1–7.

Interpretive Summary: The circadian clock confers rhythms of approximately 24 hours to many biological events in plants. The circadian system is an important contributor to plant fitness. One means by which rhythms confer a fitness advantage is to allow plants the capacity to anticipate predictable environmental changes, such as long periods of light and dark accompanying day and night. The circadian clock also allows plants to distinguish seasons. In this way, the circadian clock allows plants to time physiological activities to coincide with the most favorable environmental conditions. For example, many developmental events are circadian regulated to ensure that growth occurs at the ideal time or season relative to available resources. This review specifically discusses the impact of circadian control on plant growth and development. Circadian clock control over growth and development is often achieved through regulation of key phytohormone action. Circadian influence over the genome is widespread and the clock modulates genes involved in phytohormone synthesis and signaling, in addition to other signaling pathways shaping growth and development. This review presents four mechanisms by which temporal information is passed from the core oscillator to pathways regulating plant growth and development. We argue: 1) circadian clocks directly regulate genes for phytohormone synthesis and signaling; 2) circadian clock proteins interact with phytohormone regulators to influence growth events; 3) rhythmic transcription factors convey time cues to growth and development programs; and 4) circadian clock control of transcription through chromatin modification is beginning to be recognized as an fundamental part of circadian regulation.

Technical Abstract: The circadian clock confers rhythms of approximately 24 hours to biological events. It elevates plant fitness by allowing plants to anticipate predictable environmental changes and organize life process to coincide with the most favorable environmental conditions. Many developmental events are circadian regulated to ensure that growth occurs at the ideal time or season relative to available resources. Circadian clock control over growth and development is often achieved through regulation of key phytohormone action. Circadian influence over the genome is widespread and the clock modulates genes involved in phytohormone synthesis and signaling, in addition to other pathways shaping growth and development. This review presents four nonmutually exclusive mechanisms by which temporal information is gleaned from the core oscillator and passed to pathways regulating plant growth and development.