Mathematical modelling of the Aux/IAA negative feedback loop.
The hormone auxin is implicated in regulating a diverse range of developmental processes in plants. Auxin acts in part by inducing the Aux/IAA genes. The associated pathway comprises multiple negative feedback loops (whereby Aux/IAA proteins can repress Aux/IAA genes) that are disrupted by auxin mediating the turnover of Aux/IAA protein. In this paper, we develop a mathematical model of a single Aux/IAA negative feedback loop in a population of identical cells. The model has a single steady-state. We explore parameter space to uncover a number of dynamical regimes. In particular, we identify the ratio between the Aux/IAA protein and mRNA turnover rates as a key parameter in the model. When this ratio is sufficiently small, the system can evolve to a stable limit cycle, corresponding to an oscillation in Aux/IAA expression levels. Otherwise, the steady-state is either a stable-node or a stable-spiral. These observations may shed light on recent experimental results.
School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. alistair.middleton@nottingham.ac.uk
A M
AM
Middleton
J R
JR
King
M J
MJ
Bennett
M R
MR
Owen
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism; D025461:Feedback, Physiological; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000378:metabolism*
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C030737:indoleacetic acid