VIEW ARTICLE

Physiology and Biochemistry

Purification and Characterization of a Factor that Stimulates Tissue Maceration by Pectolytic Enzymes. Shigetaka Ishii, Senior Research Scientist, Central Research Laboratories, Kikkoman Shoyu Co., Ltd., 399 Noda, Noda-shi, Chibaken 278, Japan; Phytopathology 67:994-1000. Accepted for publication 31 January 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-994.

Aspergillus japonicus produces a factor that stimulates tissue maceration by pectolytic enzymes but cannot macerate plant tissues by itself. The factor was purified from the culture medium of this fungus by ammonium sulfate fractionation, chromatography on columns of DEAE-Sephadex and SE-Sephadex, and by gel filtration. The purified factor was homogeneous by disc electrophoresis. The pH optimum of the factor for stimulation of tissue maceration in the presence of endo-pectin lyase or endo-polygalacturonase was between 4.5 and 5.0. The factor did not stimulate the activities of endo-pectin lyase and endo-polygalacturonase when pectin and sodium polypectate were used as the substrates. The factor alone could not release any sugars from potato tuber cell walls, but it released additional galacturonides, arabinose, and galactose when incubated simultaneously with pectolytic enzymes. Similar results were obtained when cell walls which had been pretreated with pectolytic enzymes were incubated with the factor. The factor affected endo-pectin lyase and endo-polygalacturonase similarly. The ability of the factor to release additional sugars from cell walls was considerably less than its ability to stimulate tissue maceration.