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# Water-Relation Parameters of Individual Mesophyll Cells of the Crassulacean Acid Metabolism Plant Kalanchoë daigremontiana

## Lüttge, Ulrich

Plant Physiology, 1 December 1980, Vol.66(6), pp.1155-1163 [Periódico revisado por pares]

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• Título:
Water-Relation Parameters of Individual Mesophyll Cells of the Crassulacean Acid Metabolism Plant Kalanchoë daigremontiana
• Autor: Lüttge, Ulrich
• Assuntos: Biological sciences -- Biology -- Cytology ; Biological sciences -- Biology -- Cytology ; Biological sciences -- Biology -- Botany ; Biological sciences -- Biology -- Botany ; Biological sciences -- Biology -- Cytology ; Physical sciences -- Chemistry -- Chemical compounds ; Biological sciences -- Biochemistry -- Biochemical phenomena ; Physical sciences -- Physics -- Mechanics ; Biological sciences -- Biology -- Botany ; Biological sciences -- Biology -- Botany
• É parte de: Plant Physiology, 1 December 1980, Vol.66(6), pp.1155-1163
• Descrição: Water-relation parameters of leaf mesophyll cells of the CAM plant Kalanchoë daigremontiana have been determined directly in cells of tissue slices using the pressure-probe technique. Turgor pressures measured in cells of the second to fourth layer from the cut surface showed an average of 1.82 ± 0.62 bar (mean ± SD; n = 157 cells). This was lower than expected from measurements of the osmotic pressure of the cell sap. The half-time (T 1/2 ) for water-flux equilibration of individual cells was 2.5 to 8.8 seconds. This is the fastest T 1/2 found so far for higher-plant cells. The calculated values of the hydraulic conductivity were in the range of 0.20 to 1.6 × 10 -5 centimeters $\text{second}^{-1}\text{bar}^{-1}$ , with an average of (0.69 ± 0.46) × 10 -5 centimeters $\text{second}^{-1}\text{bar}^{-1}$ (mean ± SD; n = 8 cells). The T 1/2 values of water exchange of individual cells are consistent with the overall rates of water-flux equilibration measured for tissue slices. The volumetric elastic moduli (∈) of individual cells were in the range 13 to 128 bar for turgor pressures between 0.0 and 3.4 bar; the average ∈ value was 42.4 ± 27.7 bar (mean ± SD; n = 21 cells). This ∈ value is similar to that observed for other higher-plant cells. The water-storage capacity of individual cells, calculated as C c = V/(∈ + π i ) (where V = cell volume and π i = internal osmotic pressure) was 9.1 × 10 -9 cubic centimeters $\text{bar}^{-1}$ per cell, and the capacity for the tissue was 2.2 × 10 -2 cubic centimeters $\text{bar}^{-1}\text{gram}^{-1}$ fresh weight. The significance of the water-relation parameters determined at the cellular level is discussed in terms of the water relations of whole leaves and the high water-use efficiency characteristic of CAM plants.
• Idioma: Inglês