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Vacuolated plant cells as ideal osmometer: reversibility and limits of plasmolysis, and estimation of protoplasm volume in control and water‐stress‐tolerant cells
Author(s) -
PALTA JIWAN P.,
LEESTADELMANN OK YOUNG
Publication year - 1983
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/1365-3040.ep11589197
Subject(s) - protoplasm , plasmolysis , protoplast , vacuole , turgor pressure , biology , osmotic pressure , biophysics , botany , plant cell , guard cell , pisum , osmometer , osmoregulation , osmotic shock , cell wall , chemistry , microbiology and biotechnology , biochemistry , cytoplasm , chromatography , ecology , salinity , gene
. The osmotic behaviour of vacuolated plant cells (adaxial epidermal cells of Allium cepa bulb scales, and epidermal as well as chloroplast containing subepidermal stem base cells of Pisum sativum) was studied over a wide range of CaCl 2 concentrations. The following results were obtained.a. Allium cepa and Pisum sativum plant cells behave as an ideal osmometer as far as plasmolytic contraction of the protoplast is concerned. b. The protoplasts of these cells could be plasmolysed to 15–45% of their original volume without the loss of membrane semi‐permeability. c. Cells plasmolysed in 1.0 kmol m −3 CaCl 2 could be completely deplasmolysed and upon deplasmolysis the cells resumed protoplasmic streaming. d. The above findings (a‐c) indicate that during gradual plasmolysis and deplasmolysis membrane semi‐permeability is maintained. e. At very high plasmolysing concentrations vacuoles covered with the tonoplast separated from the rest of the protoplasm in some cells whereas others showed systrophy. Extruded vacuoles were able to respond to osmotic shrinkage. f. The non‐solvent space in Allium cells of about 3% also corresponded to the protoplasm volume calculated from the protoplast geometry (mean from results of direct measurement method and subtraction method). g. Subepidermal stem base cells of water‐stress‐tolerant Pisum plants had a 75% greater non‐solvent space than the control cells indicating that a water‐stress‐tolerant cell may contain a larger amount of protoplasm and/or a vacuole with a higher content of colloidal material in the vacuole. h. Water‐stress‐tolerant cells showed greater tolerance to osmotic dehydration (volume reduction) than control cells.