Premium
Light and circadian regulation of clock components aids flexible responses to environmental signals
Author(s) -
Dixon Laura E.,
Hodge Sarah K.,
Ooijen Gerben,
Troein Carl,
Akman Ozgur E.,
Millar Andrew J.
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12853
Subject(s) - circadian clock , entrainment (biomusicology) , flexibility (engineering) , biology , circadian rhythm , biological system , computer science , neuroscience , physics , mathematics , rhythm , statistics , acoustics
Summary The circadian clock measures time across a 24 h period, increasing fitness by phasing biological processes to the most appropriate time of day. The interlocking feedback loop mechanism of the clock is conserved across species; however, the number of loops varies. Mathematical and computational analyses have suggested that loop complexity affects the overall flexibility of the oscillator, including its responses to entrainment signals. We used a discriminating experimental assay, at the transition between different photoperiods, in order to test this proposal in a minimal circadian network (in O streococcus tauri ) and a more complex network (in A rabidopsis thaliana ). Transcriptional and translational reporters in O . tauri primarily tracked dawn or dusk, whereas in A . thaliana , a wider range of responses were observed, consistent with its more flexible clock. Model analysis supported the requirement for this diversity of responses among the components of the more complex network. However, these and earlier data showed that the O . tauri network retains surprising flexibility, despite its simple circuit. We found that models constructed from experimental data can show flexibility either from multiple loops and/or from multiple light inputs. Our results suggest that O . tauri has adopted the latter strategy, possibly as a consequence of genomic reduction.