Analysis of structure-property relationships in isolated cells during OD treatments. Effect of initial structure on the cell behaviour

Isolated apple cells were osmotically dehydrated in sucrose solutions (25%, 35% and 45% (w/w)) inside a heating/cooling stage with temperature control (30 °C), and examined by video-microscopy. The purpose of this work was to analyse the progress of cell microstructural changes by direct observation and further study of the digital images captured during the treatments. Cell features were identified and measured. Protoplast shrinkage increased as did sucrose concentration; however, the cell wall underwent more deformation at the lowest concentration assayed. High sucrose concentration led to an almost instantaneous protoplast separation since the membrane-to-wall linkers did not resist the stretching of the contracting protoplast; this response frequently resulted in membrane lysis and loss of cellular compartmentation. Cells structure was characterized and was proved to be related to the phenomenon undergone by the cell (shrinkage, complete plasmolysis, or membrane lysis). The response of the cell was found to be a function not only of the osmotic solution concentration but also of initial cell microstructural features. Results also suggested that a better preservation of membrane integrity and membrane-to-wall connections might be achieved if cells are dehydrated in increasingly concentrated OS solutions.