A Microrobotic System for Simultaneous Measurement of Turgor Pressure and Cell-Wall Elasticity of Individual Growing Plant Cells

Plant growth and morphogenesis is directed by cell division and the expansion of individual cells. How the tightly controlled process of cell expansion is regulated is poorly understood. We introduce a microrobotic platform able to separately measure the turgor pressure and cell wall elasticity of individual growing, turgid cells by combining microindentation with cell compression experiments. The system independently controls two indenters with geometries at different scales. Indentation measurements are performed automatically by deforming the cells with indenters with a spatial resolution in the nanometer range while recording force and displacement. The dual-indentation technique offers a noninvasive, high-throughput method to characterize the cytomechanics of single turgid cells by separately measuring elasticity and turgor pressure. In this way, the expansion regulation of growing cells can be investigated, as demonstrated here using Lilium longiflorum pollen tubes as an example.