THE PRESSURE PROBE: A Versatile Tool in Plant Cell Physiology

Abstract

This review discusses how the pressure probe has evolved from an instrument for measuring cell turgor and other water relations parameters into a device for sampling the contents of individual higher plant cells in situ in the living plant. Together with a suite of microanalytical techniques it has permitted the mapping of water and solute relations at the resolution of single cells and has the potential to link quantitatively the traditionally separate areas of water relations and metabolism. The development of the probe is outlined and its modification to measure root pressure and xylem tension described. The deployment of the pressure probe to determine and map turgor, hydraulic conductivity, reflection coefficient, cell rheological properties, solute concentrations and enzyme activities at the resolution of single cells is discussed. The controversy surrounding the interpretation of results obtained with the xylem-pressure probe is included. Possible further developments of the probe and applications of single cell sampling are suggested.

Distribution of actin gene isoforms in the Arabidopsis leaf measured in microsamples from intact individual cells

“…Increasing numbers of techniques to study the physical and chemical properties of individual living cells within organs are becoming available (reviewed by Davies 2001). One approach is based on the use of the cell pressure probe (Tomos and Leigh 1999;Tomos et al 2000). Crucially, the anatomical complexity of plants complicates the analysis of gene expression at a cellular level.…”

“…Recent advances in sampling techniques using single plant cells (see Tomos et al 1994Tomos et al , 2000Tomos and Leigh 1999;Tomos and Sharrock 2001) offer the prospects of analyzing levels of individual mRNAs from material isolated from intact fully physiological single cells. A fine microcapillary is employed to extract cell sap from the individual cells, after which RT-PCR is performed (Lambolez et al 1992;Karrer et al1995;Brandt et al 1999;Koroleva et al 2001).…”

“…The critical advantage of single-cell (SC)-RT-PCR is that it enables expression to be measured directly from living tissue at the finest spatial resolution possible, that of the individual cell. Moreover, because the microcapillary can also be used to measure, in single cells, parameters such as membrane potential, ionic status, metabolite contents and wall mechanical properties (Lambolez et al 1992;Tomos and Leigh 1999), changes in these can be linked in turn to gene expression (Koroleva et al 2001).…”

pH induced elastic modulus of guard cell wall in stomatal movement

“…The cell pressure probe is a very useful tool in studies of stomatal function [11] and is used widely to study water relations of plant cells [12][13][14]. The probe can directly and continuously measure cell turgor pressure (P), volumetric elastic modulus (ε) of the cell wall, and hydraulic conductivity (L p ) of cell membranes in single cells of higher plants.…”

“…In this paper we use a previously described cell pressure probe technique [11][12][13][14] to explore the volumetric elastic modulus of guard cell walls during stomatal movement in Vicia faba epidermal strips. The results show that reduction in pH can decrease the volumetric elastic modulus of the guard cell wall.…”