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Toxicity of Endopolygalacturonate trans-eliminase, Phosphatidase and Protease to Potato and Cucumber Tissue. T. C. Tseng, Research Assistant, Department of Plant Pathology, University of Massachusetts, Amherst 01002, Present address of senior author: Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan; M. S. Mount, Assistant Professor, Department of Plant Pathology, University of Massachusetts, Amherst 01002. Phytopathology 64:229-236. Accepted for publication 19 September 1973. DOI: 10.1094/Phyto-64-229.

Three extracellular enzymes [endopolygalacturonate trans-eliminase (endo-PGTE), phosphatidase C, and protease] produced by Erwinia carotovora were purified by ammonium sulfate fractionation, diethylaminoethyl cellulose column chromatography, and isoelectric focusing. Maceration of potato and cucumber disks occurred only when purified endo-PGTE was present in the reaction mixture. No cellular death was evident when potato tissue was treated with phosphatidase and protease, however, some cellular injury was evident when cucumber was used as the substrate. Only endo-PGTE induced leakage of 86Rb from potato disks. No leakage of 86Rb occurred from cucumber tissue when treated with any of the purified enzymes. Both phosphatidase and protease caused isolated cucumber protoplasts to burst, whereas endo-PGTE did not. Leakage of neutral red from the protoplasts was observed before, and at the time of bursting of, phosphatidase- and protease-treated protoplasts. These results suggest that endo-PGTE has no apparent effect on the membranes of cucumber protoplasts, and that phosphatidase and protease of E. carotovora may play a role in disease development.

Additional keywords: permeability change, Ampholine electrofocusing.