Pressure probe technique for measuring water relations of cells in higher plants.

A new method is described for continuously measuring cell turgor pressure (P), hydraulic conductivity (L(p)), and volumetric elastic modulus (epsilon) in higher plant cells, using a pressure probe. This technique permits volume changes, DeltaV, and turgor pressure changes, DeltaP, to be determined with an accuracy of 10(-5) to 10(-6) mul and 3 to 5.10(-2) bar, respectively.The main principle of the new method is the same as the pressure probe developed by Zimmermann and Steudle in which pressure is transmitted to a pressure transducer by means of an oil-filled capillary introduced into the cell. In order to use the pressure probe for small tissue cells, the effective compressible volume of the apparatus has to be sufficiently small in comparison to the volume of the cell itself. This is achieved by accurately fixing the oil/cell sap boundary in the very tip of the microcapillary by means of an electronic feedback mechanism, so that the effective volume of the apparatus is reduced to about 2 to 10% of the cell volume. In this way also, errors arising from compressibility of the apparatus and temperature fluctuations can be excluded.Measurements on tissues cells of Capsicum annuum fruits yield epsilon values of 2 to 25 bar. Furthermore, epsilon can be shown to be a function of both cell turgor pressure and cell volume; epsilon increases with increasing turgor pressure and is higher in larger cells.

[1]  F. Molz,et al.  Water Transport Through PLant Cells and Cell Walls: Theoretical Development , 1974 .

[2]  E. Stadelmann.  Chapter 7 Evaluation of Turgidity, Plasmolysis, and Deplasmolysis of Plant Cells , 1966 .

[3]  M. Tyree,et al.  Some possible sources of error in determining bulk elastic moduli and other parameters from pressure–volume curves of shoots and leaves , 1976 .

[4]  E. Epstein.  Mineral Nutrition of Plants: Principles and Perspectives , 1972 .

[5]  U. Zimmermann,et al.  Water relations of the epidermal bladder cells of the halophytic species Mesembryanthemum crystallinum: Direct measurements of hydrostatic pressure and hydraulic conductivity , 2004, Planta.

[6]  H. Meidner,et al.  Direct Measurements of Turgor Pressure Potentials of Guard Cells, I. , 1975 .

[7]  E. Steudle,et al.  Turgor pressure sensing in plant cell membranes. , 1976, Plant physiology.

[8]  J. R. Philip.  The Osmotic Cell, Solute Diffusibility, and the Plant Water Economy. , 1958, Plant physiology.

[9]  U. Zimmermann,et al.  The Hydraulic Conductivity and Volumetric Elastc Modulus of Cells and Isolated Cell Walls of Nitella and Chara spp.: Pressure and Volume Effects , 1975 .

[10]  T. A. Bennet-Clark,et al.  WATER RELATIONS OF PLANT CELLS. II , 1940 .

[11]  J. Dainty,et al.  A new method for measurement of hydraulic conductivity and elastic coefficients in higher plant cells using an external force , 1977 .

[12]  P. F. Scholander,et al.  HYDROSTATIC PRESSURE AND OSMOTIC POTENTIAL IN LEAVES OF MANGROVES AND SOME OTHER PLANTS. , 1964, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Melvin T. Tyree,et al.  The Measurement of the Turgor Pressure and the Water Relations of Plants by the Pressure-bomb Technique , 1972 .

[14]  P. Jarvis,et al.  Vertical Gradients of Water Potential and Tissue Water Relations in Sitka Spruce Trees Measured with the Pressure Chamber , 1974 .

[15]  U. Zimmermann,et al.  Turgor Pressure Regulation in Valonia utricularis: Effect of Cell Wall Elasticity and Auxin. , 1976, Plant physiology.

[16]  J. Dainty.  Water Relations of Plant Cells , 1976 .