The influence of cold acclimation on the behavior of the plasma membrane following osmotic contraction of isolated protoplasts

Osmotic contraction of protoplasts isolated from cold acclimated leaves of Secale cereale . L. cv. Puma results in the formation of exocytotic extrusions of the plasma membrane. Numerous knobs or polyps were observed on the surface of the protoplasts with scanning electron microscopy. Together, the findings suggest that during hypertonic contraction of acclimated protoplasts, lipid material is preferentially subducted from the plasma membrane and sequestered into lipid bodies (the osmiophilic regions). The formation of lipid bodies and extrusions was readily reversible. Following osmotic expansion of acclimated protoplasts, the extrusions were retracted back into the plane of the plasma membrane.