Protocol for mapping the variability in cell wall mechanical bending behavior in living leaf pavement cells

Abstract

Mechanical properties, size and geometry of cells and internal turgor pressure greatly influence cell morphogenesis. Computational models of cell growth require values for wall elastic modulus and turgor pressure, but very few experiments have been designed to validate the results using measurements that deform the entire thickness of the cell wall. New wall material is synthesized at the inner surface of the cell such that full-thickness deformations are needed to quantify relevant changes associated with cell development. Here, we present an integrated, experimental-computational approach to analyze quantitatively the variation of elastic bending behavior in the primary cell wall of living Arabidopsis (Arabidopsis thaliana) pavement cells and to measure turgor pressure within cells under different osmotic conditions. This approach used laser scanning confocal microscopy to measure the three-dimensional geometry of single pavement cells and indentation experiments to probe the local mechanical responses across the periclinal wall. The experimental results were matched iteratively using a finite element model of the experiment to determine the local mechanical properties and turgor pressure. The resulting modulus distribution along the periclinal wall was nonuniform across the leaf cells studied. These results were consistent with the characteristics of plant cell walls which have a heterogeneous organization. The results and model allowed the magnitude and orientation of cell wall stress to be predicted quantitatively. The methods also serve as a reference for future work to analyze the morphogenetic behaviors of plant cells in terms of the heterogeneity and anisotropy of cell walls.

Young guard cells function dynamically despite low mechanical anisotropy but gain efficiency during stomatal maturation in Arabidopsis thaliana

“…Previous reports highlighted the importance of computational models to determine the mechanical properties of biological systems (Boudon et al 2015; Forouzesh et al 2013; Hayot et al 2012; Li et al 2022; Woolfenden et al 2017). We used nanoindentation coupled with finite element (FE) modeling to characterize the mechanical traits of young and mature guard cells, including cell wall moduli in different directions and turgor pressure (Fig.…”

Rigidity control mechanism by turgor pressure in plants

“…The rigidity imbued by their hard bodies allows these species to resist the effects of gravity and wind. In contrast, the fleshy components of herbaceous plants are much softer than those of woody plants, having almost hollow cross-sections and extremely small diameters 16 , 22 – 25 . For herbaceous plants with such characteristics, the simple acquisition of bending rigidity is insufficient to support their bodies.…”

“…Consequently, herbaceous plants utilize the turgor pressure associated with their internal water content to maintain their rigidity 22 , 25 – 34 . In herbaceous plants, when the inflow of water exceeds the outflow of water from inside a cell, turgor pressure is generated to equalize the pressure inside and outside the cell.…”

Rigidity Control Mechanism by Turgor Pressure in Plants

“…The rigidity imbued by their hard bodies allows these species to resist the effects of gravity and wind. In contrast, the fleshy components of herbaceous plants are much softer than those of woody plants, having almost hollow cross-sections and extremely small diameters [16,[22][23][24][25] . For herbaceous plants with such characteristics, the simple acquisition of bending rigidity is insufficient to support their bodies.…”

“…Consequently, herbaceous plants utilize the turgor pressure associated with their internal water content to maintain their rigidity [22,[25][26][27][28][29] . In herbaceous plants, when the inflow of water exceeds the outflow of water from inside a cell, turgor pressure is generated to equalize the pressure inside and outside the cell.…”