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

The overall washing out of ions, especially 86 Rb + (as the tracer for K + ), from hypocotyl segments of pumpkin ( Cucurbita pepo L.) into distilled water or a CaCl 2 solution was studied, during plasmolysis with a saccharose solution and during deplasmolysis. Compartimental analysis was used to evaluate the 86 Rb + washing out kinetics. During plasmolysis, the washing out of 86 Rb + increases, due to two processes whose half-times are lower than those during washing out into the CaCl 2 solution. During deplasmolysis, the permeability of plasmalemma and tonoplast is substantially descreased, leading to washing out of most 86 Rb + 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.