Abstract
Stationary volume fluxes through living and denatured parenchyma slices of the potato (Solanum tuberosum L.) storage organ were studied to estimate the hydraulic conductivity of the cell wall and to evaluate the significance of water transport through protoplasts, cell walls, and intercellular spaces. Slices were placed between liquid compartments, steady-state fluxes induced by pressure or concentration gradients of low- and high-molecular-mass osmotica were measured, and water transport pathways were distinguished on the basis of their difference in limiting pore size. The protoplasts were the dominating route for osmotically driven water transport through living slices, even in the case of a polymer osmoticum that is excluded from cell walls. The specific hydraulic conductivity of the cell wall matrix is too small to allow a significant contribution of the narrow cell wall bypass to water flow through the living tissue. This conclusion is based on (a) ultrafilter coefficients of denatured parenchyma slices, (b) the absence of a significant difference between ultrafilter coefficients of the living tissue slices for osmotica with low and high cell wall reflection coefficients, and (c) the absence of a significant interaction (solvent drag) between apoplasmic permeation of mannitol and the water flux caused by a concentration difference of excluded polyethylene glycol. Liquid-filled intercellular spaces were the dominating pathways for pressure-driven volume fluxes through the parenchyma tissue.
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Selected References
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- Carpita N. C. Limiting diameters of pores and the surface structure of plant cell walls. Science. 1982 Nov 19;218(4574):813–814. doi: 10.1126/science.218.4574.813. [DOI] [PubMed] [Google Scholar]
- Ferrier J. M., Dainty J. Water Flow in Beta vulgaris Storage Tissue. Plant Physiol. 1977 Nov;60(5):662–665. doi: 10.1104/pp.60.5.662. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hüsken D., Steudle E., Zimmermann U. Pressure probe technique for measuring water relations of cells in higher plants. Plant Physiol. 1978 Feb;61(2):158–163. doi: 10.1104/pp.61.2.158. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KATCHALSKY A., KEDEMO Thermodynamics of flow processes in biological systems. Biophys J. 1962 Mar;2(2 Pt 2):53–78. doi: 10.1016/s0006-3495(62)86948-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Radin J. W., Matthews M. A. Water transport properties of cortical cells in roots of nitrogen- and phosphorus-deficient cotton seedlings. Plant Physiol. 1989 Jan;89(1):264–268. doi: 10.1104/pp.89.1.264. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Steudle E., Murrmann M., Peterson C. A. Transport of Water and Solutes across Maize Roots Modified by Puncturing the Endodermis (Further Evidence for the Composite Transport Model of the Root). Plant Physiol. 1993 Oct;103(2):335–349. doi: 10.1104/pp.103.2.335. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Woolley J. T. Maintenance of air in intercellular spaces of plants. Plant Physiol. 1983 Aug;72(4):989–991. doi: 10.1104/pp.72.4.989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhu G. L., Steudle E. Water Transport across Maize Roots : Simultaneous Measurement of Flows at the Cell and Root Level by Double Pressure Probe Technique. Plant Physiol. 1991 Jan;95(1):305–315. doi: 10.1104/pp.95.1.305. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zimmermann U., Rygol J., Balling A., Klöck G., Metzler A., Haase A. Radial Turgor and Osmotic Pressure Profiles in Intact and Excised Roots of Aster tripolium: Pressure Probe Measurements and Nuclear Magnetic Resonance-Imaging Analysis. Plant Physiol. 1992 May;99(1):186–196. doi: 10.1104/pp.99.1.186. [DOI] [PMC free article] [PubMed] [Google Scholar]