Seasonal regulation of the circadian clock in Arabidopsis thaliana

Williams, Stephanie S. I. (2023) Seasonal regulation of the circadian clock in Arabidopsis thaliana. Doctoral thesis, University of East Anglia.

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Abstract

Circadian clocks are ubiquitous across life and have commonly evolved from the evolutionary pressures that come from living on a rotating planet. They drive rhythmic patterns of gene expression, approximately every 24 hours, enabling individuals to coordinate the timing of physiological and developmental process to optimally align with environmental conditions across both daily and season timescales.

Plants monitor the progression of seasons in two broad ways: through photoperiodism, and long-term temperature sensing. While photoperiod is a major indicator of seasonal progression for plants, vernalisation provides an additional layer of regulation ensuring that the reproductive transition only occurs after exposure to prolonged winter cold. Prior research has highlighted a potential feedback loop between the vernalisation pathway, its output FLOWERING LOCUS C (FLC), and the circadian clock to communicate seasonal information within the plant. However, this possibility has remained largely unexplored.

Using Arabidopsis thaliana as a model, I demonstrate that exposure to vernalising winter cold affects the temporal dynamics of specific oscillator components under subsequent spring-like conditions. Through systematic disruption of the vernalisation pathway, I identify this response requires VERNALISATION 2 (VRN2), a core component of the evolutionarily conserved polycomb repressive complex 2 (PRC2). Unexpectedly, FLC expression was not essential for this process. Analysis of downstream transcription, and broader physiological processes, reveal that these seasonal changes in circadian dynamics extended beyond core oscillator components. This work then led me to an intriguing exploration of how the promoter dynamics of circadian clock components behave under different photoperiods. Collectively, these behaviours likely provide adaptive benefits by aligning whole plant physiology with the new spring environment. The insights from my work may help to predict the effects of climate change on plant physiology and development, with implications for both crops and natural plant populations.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	18 May 2026 08:58
Last Modified:	18 May 2026 08:58
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103055
DOI:

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