VIEW ARTICLE

Endopolygalacturonase: Evidence Against Involvement in Verticillium Wilt of Cotton. N. T. Keen, Assistant Professor, Department of Plant Pathology, University of California, Riverside 92502; D. C. Erwin, Professor, Department of Plant Pathology, University of California, Riverside 92502. Phytopathology 61:198-203. Accepted for publication 22 September 1970. DOI: 10.1094/Phyto-61-198.

Thirteen isolates of Verticillium albo-atrum produced extracellular endopolygalacturonase (endo-PG) inducibly in culture, but rates of production in artificial media showed no relationship to virulence on cotton plants. Enzyme synthesis in the presence of the inducer sodium polypectate was repressed by 0.1 m glucose and stimulated by 0.01 m glucose. Low activities of endo-PG were extracted from severely infected cotton plants, but the activity recovered was not related to virulence of the isolates used. Cotton cuttings wilted when placed in dialyzed crude culture fluids, but exhibited no symptoms when placed in highly purified, apparently homogeneous preparations of V. albo-atrum endo-PG. These results argue against endo-PG as a factor in development of Verticillium wilt of cotton.