Effects of Phosfon-D and of low temperature on the morphology of cell protoplasts

Summary The adventitious roots of onion (Allium cepa L.) or onion bulb scales were treated either with growth retardant Phosfon-D (2,4-dichlorobenzyltributylphosfonium chloride), or with low temperature (5° C). Low temperature, likewise Phosfon-D treatment, resulted in the appearance of membranous structures within the cytoplasm of the root cells fixed in chromaceto-formalin (CrAF) and in the occurrence of minute vacuoles in the living onion bulb scale cells. The cytochemical analysis revealed the membrane-like elements to contain basic and acid proteins as well as nucleic acids.It seems that the observed effect of Phosfon-D and that of low temperature were due to the local accumulation of protein resulting in changes of the physical properties of the cytoplasm. The fact that membranous structures do contain nucleic acid may suggest their important, metabolic role especially in the process of cold acclimation of plant tissue.This work was partly supported by Grant No. FG-PO-225 from U.S. Department of Agriculture, Agricultural Research Program, Public Law 480.