title: A Compact Model for the Complex Plant Circadian Clock.
abstract: The circadian clock is an endogenous timekeeper that allows organisms to anticipate and adapt to the daily variations of their environment. The plant clock is an intricate network of interlocked feedback loops, in which transcription factors regulate each other to generate oscillations with expression peaks at specific times of the day. Over the last decade, mathematical modeling approaches have been used to understand the inner workings of the clock in the model plant Arabidopsis thaliana. Those efforts have produced a number of models of ever increasing complexity. Here, we present an alternative model that combines a low number of equations and parameters, similar to the very earliest models, with the complex network structure found in more recent ones. This simple model describes the temporal evolution of the abundance of eight clock gene mRNA/protein and captures key features of the clock on a qualitative level, namely the entrained and free-running behaviors of the wild type clock, as well as the defects found in knockout mutants (such as altered free-running periods, lack of entrainment, or changes in the expression of other clock genes). Additionally, our model produces complex responses to various light cues, such as extreme photoperiods and non-24 h environmental cycles, and can describe the control of hypocotyl growth by the clock. Our model constitutes a useful tool to probe dynamical properties of the core clock as well as clock-dependent processes.
authors.affiliation: Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Joëlle
authors.initials: J
authors.lastname: De Caluwé
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Faculté des Sciences, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Qiying
authors.initials: Q
authors.lastname: Xiao
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Faculté des Sciences, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Christian
authors.initials: C
authors.lastname: Hermans
authors.affiliation: Laboratory of Plant Physiology and Molecular Genetics, Faculté des Sciences, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Verbruggen
authors.affiliation: Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Leloup
authors.affiliation: Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles Brussels, Belgium.
authors.forename: Didier
authors.initials: D
authors.lastname: Gonze
keywords: Arabidopsis thaliana; circadian rhythms; clock mutants; entrainment by light–dark cycles; mathematical model