Simultaneous quantification of cell wall elasticity and turgor pressure in live plant cells by elastic shell theory analysis and AFM.

Main conclusion: Our method can simultaneously quantify cell wall elasticity and turgor pressure of live plant cells through AFM measurements and calculations based on elastic shell theory. The morphological behavior of plant cells depends on their mechanical properties. Cell wall elasticity (E) and turgor pressure (P) are main factors that dominate the behavior. A method to simultaneously quantify them in live cells has yet to be established, hindering progress in plant mechanobiology. Recently, atomic force microscopy (AFM) has been used to analyze single cells based on Hertz's contact theory (HCT). However, HCT cannot evaluate P. Several groups have attempted to evaluate P by adapting elastic shell theory (EST), but it is still difficult to estimate both E and P from the indentation data and EST alone. Herein an analytical method is proposed based on EST using the cell indentation and surface geometry from the AFM measurements. We also demonstrate the reliability of our approach under various osmotic pressure conditions and simultaneously determine the values of P and E in epidermal monolayer cells of an Allium cepa L.