EFFECTS OF CADMIUM ON THE HOST-PATHOGEN SYSTEM .4. INFLUENCE OF CADMIUM AND PHYTOPHTHORA-INFESTANS ON MEMBRANE-PERMEABILITY OF POTATO-TUBER

Changes in electrolyte leakage, and Ca+2, K+, and Cl- effluxes from po tato (Solanum tuberosum L.) tubers in response to either cadmium or Ph ytophthora infestans, or both, were investigated. Two cultivars, Bintj e and Bzura, susceptible and resistant, respectively, to pathogen and cadmium were examined. Long-term exposure of the plant to cadmium, res ulting in the presence of cadmium in tubers (0.1-20 mug g-1 fw) caused an increase of membrane integrity in the organs of both cultivars. As a result of the interaction between the tuber slices and pathogen mar ked increases in electrolyte leakage, and in K+, and Cl- effluxes from susceptible material as well as in Ca+2 efflux from resistant materia l were observed. A simultaneous treatment of potato tubers of both cul tivars with cadmium and pathogen brought about antagonistic effects in membrane permeability.