Sarah Richards - AG Rose

In Arabidopsis thaliana primary roots, the quiescent center (QC) and surrounding cells make up the stem cell niche, a domain where stem cells can be maintained to renew and replenish the differentiated cell population. Communication between these cells via extracellular ligands (often peptides secreted by the cells), membrane-bound receptors, plasmodesmata, and carriers influence the regulatory networks within each cell to control the cell's type. Cell fate refers to this categorization of cell type, and it includes QC, specialized stem cells, differentiated cells, and cell types between stem and fully differentiated. A specific number of QC and stem cells are maintained with very little deviation in their number and relative position over time.

This project aims to mathematically describe interactions between components of the regulatory network in each cell as well as diffusion and transport of the signaling molecules between cells, with particular attention paid to the homeostasis of stem cell number and location in the stem cell niche. Results of the model will predict the fate of each cell based on the following:

1) Initial conditions, the starting values of component concentrations

2) Increased concentration of certain components, simulating processes such as flooding with peptide, a common experimental technique.

3) Changes to the system brought about by parameter adjustments to simulate mutants. Examples of parameters are the production rates of particular transcription factors, diffusion constants, and binding affinities between transcription factors and promoters.

If the model can accurately predict experimental outcomes, then we will gain clues to which components are most vital for maintenance of this robust cell fate determination, which mechanisms are necessary to move signals from their source cell to their target cell, and how the root may react to conditions which cannot currently be produced by experiment.

Starting date: 01.08.2012 / PhD student

Thesis committee members: Laura Rose, Achim Schädle, Andreas Weber

Mini Academic CV:

  •  2012:
    • M.Sc. in Applied Mathematics from Michigan State University, (Lansing, MI, US)
  • 2009:
    • B.Sc. in Mathematics from Eastern Michigan University, (Ypsilanti, MI, US)


Richards S, Wink RH, Simon R (2015) Mathematical modelling of WOX5-and CLE40-mediated columella stem cell homeostasis in Arabidopsis. J Exp Bot. Aug;66(17):5375-84.

Responsible for the content: E-MailDr. Petra Fackendahl