VIEW ARTICLE

Physiology and Biochemistry

Absence of Cell Wall Polysaccharide Degradation by Erwinia amylovora. E. A. Seemüller, Visiting Scientist, Department of Plant Pathology, Cornell University, Ithaca, New York 14853, Present address of senior author: Institut für Obstkrankheiten, Biologische Bundesanstalt, 6901 Dossenheim, W. Germany; S. V. Beer, Assistant Professor, Department of Plant Pathology, Cornell University, Ithaca, New York 14853. Phytopathology 66:433-436. Accepted for publication 25 September 1975. DOI: 10.1094/Phyto-66-433.

The composition of the cell wall polysaccharides prepared from Erwinia amylovora-infected and noninfected Cotoneaster pannosa and Malus sylvestris shoot and immature Pyrus communis fruit tissues was determined by gas-liquid chromatographic, wet chemical, and enzymatic techniques. Infected and comparable noninfected tissues did not differ significantly in the percentage composition of arabinose, xylose, glucose, galactose, mannose, rhamnose, galacturonic acid, or cellulose. No pectolytic, cellulolytic, or xylolytic enzyme activity was detected in extracts of infected shoots or in ooze produced during infection of pear fruits. No pectolytic enzymes were detected in the filtrates of ten liquid media in which the pathogen had grown. Maceration of infected pear fruit tissue was not observed. Potato tuber and pear fruit disks were not macerated when treated with the supernatant liquid of bacterial ooze or extracts of infected tissues. This work indicates that cell wall polysaccharide degradation is absent during the development of the fire blight disease.