Coupled experimental and computational study of the interplay of mechanical properties and chemical signaling in stem cell patterns in plants.

One of the central problems in developmental biology is the determination of how chemical and mechanical signals interact within a tissue to produce the final form, size and function of an organ. Cell walls in plants impose a unique constraint since cells are under turgor pressure and cannot move relative to one another. Cell wall extensibility and distribution of stress on the wall contribute to determining rates of cell expansion and orientation of cell division. How cell wall mechanical properties influence cell behavior is still largely unknown. First, a novel, multi-scale, computational model of the development of the shoot apical meristem (SAM) of Arabidopsis is described and calibrated using experimental data. Biologically relevant features of the model include separate representations of the cell wall and cytoplasm and a detailed description of extensibility and distribution of stress on the cell wall. Model predictive simulations reveal relative impacts of cell wall extensibility, distribution of stress, and chemical signals on growth rate and division plane orientation in the SAMs resulting in better understanding of the relationship between local morphogenetic processes and global tissue patterns in stem cell maintenance and differentiation.