Morphogengineering roots: comparing mechanisms of morphogen gradient formation
1 Computational & Systems Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
2 Molecular Genetics Group, Dept. of Biology, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
3 Theoretical Biology Group, Dept. of Biology, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
BMC Systems Biology 2012, 6:37 doi:10.1186/1752-0509-6-37Published: 14 May 2012
In developmental biology, there has been a recent focus on the robustness of morphogen gradients as possible providers of positional information. It was shown that functional morphogen gradients present strong biophysical constraints and lack of robustness to noise. Here we explore how the details of the mechanism which underlies the generation of a morphogen gradient can influence those properties.
We contrast three gradient-generating mechanisms, (i) a source-decay mechanism; and (ii) a unidirectional transport mechanism; and (iii) a so-called reflux-loop mechanism. Focusing on the dynamics of the phytohormone auxin in the root, we show that only the reflux-loop mechanism can generate a gradient that would be adequate to supply functional positional information for the Arabidopsis root, for biophysically reasonable kinetic parameters.
We argue that traits that differ in spatial and temporal time-scales can impose complex selective pressures on the mechanism of morphogen gradient formation used for the development of the particular organism.