Strand 2: The Root Apical Meristem.
Strand 2 will focus on the root apical meristem, the principal site for cell division during primary root growth. We will build here on the results of Strand 1 primarily by extending models to include additional cell types, cell division and the development of tissue heterogeneity in response to the positional information generated by gradients of signals such as auxin.
Accordingly, biochemical-network models will also be enhanced by adding pathways needed for cell division, namely the changes in gene expression associate
d with S-phase, mitosis and formation of a new cell wall. The models will be tested and refined by extending the expression profiling analyses to include
the extra cell types, by experimentally manipulating the auxin gradient at the root apex and quantifying the associated changes in transcription rates.
Multi-scale modelling will be used to account for the creation of the auxin gradient and for the associated patterning of the multilayer structure (which is imposed in Strand 1 but which will arise here as an emergent property). This will require adaptive methodologies for image s egmentation, cell tracking and FE analysis, which identify when a cell is about to divide and spawn two elements where previously there was only one. The ability of the models to reproduce, and provide intuition into the delicate balance that must in practice be achieved between, for instance, mitotic rates in neighbouring layers will provide stringent tests of their predictive capability.