The effect of plasmolysis and deplasmolysis on the permeability of plant membranes

Abstract

The overall washing out of ions, especially⁸⁶Rb⁺ (as the tracer for K⁺), from hypocotyl segments of pumpkin (Cucurbita pepo L.) into distilled water or a CaCl₂ solution was studied, during plasmolysis with a saccharose solution and during deplasmolysis. Compartimental analysis was used to evaluate the⁸⁶Rb⁺ washing out kinetics. During plasmolysis, the washing out of⁸⁶Rb⁺ increases, due to two processes whose half-times are lower than those during washing out into the CaCl₂ solution. During deplasmolysis, the permeability of plasmalemma and tonoplast is substantially descreased, leading to washing out of most⁸⁶Rb⁺ from the cells. Plasmolysis differs from a mere decrease in the turgor pressure in the fact that after exchange for a hypotonic solution the membranes are irreversibly damaged.

The aim of this work was to monitor the changes in the cell membrane permeability due to a change in the water potential of the cells, especially during plasmolysis and deplasmolysis.