Computational modeling of plant trichome branch growth using finite element and imaging approaches
Anastasia Desyatova (University of Nebraska-Lincoln, Mechanical and Materials Engineering), Samuel Belteton (Purdue University, Agronomy), Makoto Yanagisawa (Purdue University, Agronomy), Tzu-Ching Wu (Purdue University, Agricultural and Biological Engineering), Daniel Szymanski (Purdue University, Agronomy), David Umulis (Purdue University, Agricultural and Biological Engineering), Joseph Turner (University of Nebraska-Lincoln, Mechanical and Materials Engineering)
Joint Session: Mechanics of cell sheets, multicellular assemblies and tissues and Mechanics and Physics of Biological Cells
Mon 2:40 - 4:00
Barus-Holley 141
Plant cell growth plays a central role in plant development. Several biophysical and mathematical models exist to describe diffuse growth that occurs uniformly at the cell surface. However, most of these models are applicable to simple geometries and give only a general understanding of the global cell growth. At the same time important epidermal cell types that control organ geometry, such as trichomes in Arabidopsis thaliana, have complex shapes and grow non-uniformly. In this presentation, the expansion of the trichome cell wall is simulated with respect to geometric and material properties. Optical microscopy-based imaging is used to characterize the growth of a trichome branch. The branch is modeled as a shell reservoir subjected to constant hydrostatic turgor pressure. The cell wall is modeled as a viscoelastic hyperelastic material with spatially varying properties. Growth is modeled as a sequence of cell wall expansions (due to turgor) and regeneration (due to synthesis of new wall material). Model results are compared with experimental growth pattern data in terms of branch tip curvature, temporal variability of the branch length and width, and overall shape of the cell. The results show that the spatial variation of mechanical properties significantly affects cell growth patterns. This variation is responsible for the transition of growth shape from a uniform expansion in all directions to the more directional growth at the tip as observed in trichomes. A combination of isotropic (at the tip) and anisotropic (at the rest of the cell) constitutive models resulted in the most realistic growth. The set of constitutive material parameters determined allows the experimentally observed cell growth patterns to be predicted. We envision that this model can be used to predict cell growth, which may be helpful in understanding how biochemical factors and cytoskeleton components influence mechanical properties in the trichome wall. [Research supported by NSF]