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SUMMARY Daily rhythms in physiology are obvious and widespread. While for millennia it was thought that these cycles represent passive responses to environmental cycles, we now recognize that many of them are governed by circadian oscillators. In plants, these cell‐autonomous oscillators regulate daily processes such as photosynthesis, organ growth, and hormone production, as well as seasonal transitions like flowering. Furthermore, the circadian system gates plant responses to biotic and abiotic stresses, modulating susceptibility to pathogens and environmental extremes in a time‐of‐day‐dependent manner. Variants of circadian clock genes have been repeatedly selected during crop domestication and improvement, highlighting the importance of the circadian system to plants and its relevance for agriculture. Here, I review the history of circadian studies in plants and summarize our current understanding of the molecular nature of the circadian oscillator. I also discuss how this complex network both responds to and is buffered against changes in the environment. Next, I examine how circadian oscillators differ between various tissues and how their activities are coordinated throughout the plant body. Finally, I discuss emerging directions, such as ways in which this understanding can be applied to crop improvement in the face of climate change.
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Early birds and night owls: natural variation of circadian traits in plants
Abstract Circadian clocks have long been hypothesized to tightly link cellular and physiological processes to the appropriate time within the 24-hour cycle of the Earth’s daily rotation. According to this hypothesis, circadian rhythms with cycle lengths that differ significantly from 24 hours would be disadvantageous, as they would generate a desynchronization between the endogenous and exogenous cycles that would place stress upon an organism through the required daily resetting at dawn. However, recent work has demonstrated that endogenous circadian cycles that differ from 24 hours by 2 hours or more are prevalent within the green lineage. Herein, we review recent work on the prevalence of, and adaptive advantages associated with, natural variation in circadian cycles. Based on known photoperiodic sensing mechanisms we also describe a set of principles that allow the same changes in circadian period to cause different plant responses. This fine-tuning of clock output pathways provides a flexible mechanism enabling plants to use a wide range of life history strategies for plant adaptation to different environmental niches. Further studies are needed to determine how variations of the clock and other signals are integrated in different plants. These studies highlight the circadian clocks’ position as a prime adaptation target for migration of plant species into new environmental ranges.
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- Award ID(s):
- 1950376
- PAR ID:
- 10670831
- Editor(s):
- Lunn, John
- Publisher / Repository:
- Oxford Academic
- Date Published:
- Journal Name:
- Journal of Experimental Botany
- ISSN:
- 0022-0957
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/jxb/erag013
