FUNCTIONAL AND STRUCTURAL ALTERATIONS OF PLASMA-MEMBRANE OF POTATO-TUBER DURING THE HYPERSENSITIVE RESPONSE TO ELICITOR FROM PHYTOPHTHORA-INFESTANS

The degree of the hypersensitive tissue response to crude elicitor from Phytophthora infestans differed with cultivars. On this basis, a comparative study was conducted to test how the intensity of tissue response is associated with events that are credited with a role in this response. Conductivity and pH measurements revealed that the degree of rapid alterations in ion transport were inversely correlated with the intensity of tissue response. This functional change is likely to be due to a direct effect of elicitor on the plasma membrane. The elicitor, in addition, caused membrane lipid peroxidation, presumably through the generation of toxic free radicals. The indirect effect of elicitor appeared late and was loosly associated with the intensity of tissue browning and necrotization. It is concluded that the development of necroses is regulated by a series of biophysical and biochemical mechanisms, among which those discussed represent a limited part.