Abstract

Emergence of new lateral roots from within the primary root in Arabidopsis has been shown to be regulated by the phytohormone auxin, via the expression of the auxin influx carrier LAX3, mediated by the ARF7/19 IAA14 signalling module (Swarup et al., 2008). A single cell model of the LAX3 and IAA14 auxin response was formulated and used to demonstrate that hysteresis and bistability may explain the experimentally observed 'all-or-nothing' LAX3 spatial expression pattern in cortical cells containing a gradient of auxin concentrations. The model was tested further by using a parameter fitting algorithm to match model output with qRT-PCR mRNA expression data following exogenous auxin treatment It was found that the model is able to show good agreement with the data, but only when the exogenous auxin signal is degraded over time, at a rate higher than that measured in the experimental medium, suggesting the triggering of an endogenous auxin homeostasis mechanism. Testing the model over a more physiologically relevant range of extracellular auxin shows bistability and hysteresis still occur when using the optimised parameters, providing the rate of LAX3 active auxin transport is sufficiently high relative to passive diffusion. (C) 2014 Elsevier Ltd. All rights reserved.

Keywords

Plant lateral root development; Mathematical modelling; Auxin degradation

Published in

Journal of Theoretical Biology
2015, Volume: 366, pages: 57-70
Publisher: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

SLU Authors

• Sairanen, Ilkka

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Ljung, Karin

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Bioinformatics and Systems Biology


Publication identifier

DOI: https://doi.org/10.1016/j.jtbi.2014.11.003

Permanent link to this page (URI)

https://res.slu.se/id/publ/73906