Hubbard, Katharine , Dodd, Antony , Gardner, Michael , Hotta, Carlos , Dalchau, Neil , Davies, Julia , Webb, Alex .
Dissection of Calcium Signalling Pathways in the Arabidopsis Circadian Clock.
A wide variety of plant physiological processes are circadian regulated. Studies of the model plant Arabidopsis thaliana have demonstrated the existence of a molecular clock based on a transcriptional feedback loop, with a free running period of 24 hours. There are circadian oscillations of cytosolic free calcium concentration ([Ca2+]cyt), but signalling processes both upstream and downstream of these [Ca2+]cyt rhythms are unclear at present. We have used a systems approach consisting of mathematical, bioniformatic, transcriptomic, transgenic, reverse genetic, pharmacological and physiological tools to identify putative components of the circadian signalling network. The systems analysis identifies the second messenger cADPR as having a role in the maintenance of circadian [Ca2+]cyt rhythms. Characterisation of circadian responses to elevated ADPR cyclase expression are being conducted in order to further elucidate how the generation of circadian [Ca2+]cyt oscillations affects the core oscillator and downstream responses. In parallel, we performed circadian whole genome transcriptome analysis to identify signalling transcripts whose expression was clock controlled. Using a reverse genetic approach we analysed the role of these transcripts in the regulation of circadian rhythms of leaf movement and photoperiodic flowering time. We are extending our analyses of the roles of [Ca2+]cyt in the circadian signalling network by investigating the patterns of oscillations of [Ca2+]cyt in signalling and circadian mutants.
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1 - University of Cambridge, Plant Sciences, Downing Site, Cambridge, CB2 3EA, UK
2 - University of Cambridge, Plant Sciences
Presentation Type: ASPB Minisymposium
Location: Continental B/Hilton
Date: Sunday, July 8th, 2007
Time: 4:10 PM