Light inputs shape the Arabidopsis circadian system

Bénédicte Wenden, László Kozma-Bognár, Kieron D Edwards, Anthony J W Hall, James C W Locke, Andrew J Millar

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The circadian clock is a fundamental feature of eukaryotic gene regulation that is emerging as an exemplar genetic sub-network for systems biology. The circadian system in Arabidopsis plants is complex, in part due to its phototransduction pathways, which are themselves under circadian control. We therefore analysed two simpler experimental systems. Etiolated seedlings entrained by temperature cycles showed circadian rhythms in the expression of genes that are important for the clock mechanism, but only a restricted set of downstream target genes were rhythmic in microarray assays. Clock control of phototransduction pathways remained robust across a range of light inputs, despite the arrhythmic transcription of light-signalling genes. Circadian interactions with light signalling were then analysed using a single active photoreceptor. Phytochrome A (phyA) is expected to be the only active photoreceptor that can mediate far-red (FR) light input to the circadian clock. Surprisingly, rhythmic gene expression was profoundly altered under constant FR light, in a phyA-dependent manner, resulting in high expression of evening genes and low expression of morning genes. Dark intervals were required to allow high-amplitude rhythms across the transcriptome. Clock genes involved in this response were identified by mutant analysis, showing that the EARLY FLOWERING 4 gene is a likely target and mediator of the FR effects. Both experimental systems illustrate how profoundly the light input pathways affect the plant circadian clock, and provide strong experimental manipulations to understand critical steps in the plant clock mechanism.
Original languageEnglish
Pages (from-to)480-491
Number of pages12
JournalThe Plant Journal
Issue number3
Early online date4 Mar 2011
Publication statusPublished - 31 May 2011

Keywords / Materials (for Non-textual outputs)

  • Arabidopsis
  • Arabidopsis Proteins
  • Circadian Clocks
  • DNA-Binding Proteins
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant
  • Photoperiod
  • Phytochrome A
  • Seedling
  • Temperature
  • Transcription Factors
  • circadian rhythms
  • biological clocks
  • Arabidopsis thaliana
  • far red light
  • Phytochrome
  • gene circuit


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