Modeling the organization of the WUSCHEL expression domain in the shoot apical meristem.
BACKGROUND
The above-ground tissues of higher plants are generated from a small region of cells situated at the plant apex called the shoot apical meristem. An important genetic control circuit modulating the size of the Arabidopsis thaliana meristem is a feed-back network between the CLAVATA3 and WUSCHEL genes. Although the expression patterns for these genes do not overlap, WUSCHEL activity is both necessary and sufficient (when expressed ectopically) for the induction of CLAVATA3 expression. However, upregulation of CLAVATA3 in conjunction with the receptor kinase CLAVATA1 results in the downregulation of WUSCHEL. Despite much work, experimental data for this network are incomplete and additional hypotheses are needed to explain the spatial locations and dynamics of these expression domains. Predictive mathematical models describing the system should provide a useful tool for investigating and discriminating among possible hypotheses, by determining which hypotheses best explain observed gene expression dynamics.


RESULTS
We are developing a method using in vivo live confocal microscopy to capture quantitative gene expression data and create templates for computational models. We present two models accounting for the organization of the WUSCHEL expression domain. Our preferred model uses a reaction-diffusion mechanism in which an activator induces WUSCHEL expression. This model is able to organize the WUSCHEL expression domain. In addition, the model predicts the dynamical reorganization seen in experiments where cells, including the WUSCHEL domain, are ablated, and it also predicts the spatial expansion of the WUSCHEL domain resulting from removal of the CLAVATA3 signal.


BACKGROUND
An extended description of the model framework and image processing algorithms can be found at http://www.computableplant.org, together with additional results and simulation movies.


BACKGROUND
http://www.computableplant.org/ and alternatively for a direct link to the page, http://computableplant.ics.uci.edu/bti1036 can be accessed.
Jönsson
Henrik
H
Department of Theoretical Physics, Complex Systems Division, Lund University Sweden.
Heisler
Marcus
M
Reddy
G Venugopala
GV
Agrawal
Vikas
V
Gor
Victoria
V
Shapiro
Bruce E
BE
Mjolsness
Eric
E
Meyerowitz
Elliot M
EM
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis; D019295:Computational Biology / Q000379:methods; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000096:biosynthesis; D018519:Meristem / Q000378:metabolism*; D018613:Microscopy, Confocal; D010940:Plant Proteins; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis; D012984:Software; D015854:Up-Regulation
C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D010940:Plant Proteins; C116421:WUSCHEL protein, Arabidopsis; D020794:Receptor Protein-Tyrosine Kinases; C118166:CLV1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases