Evidence for adherence of host plasmalemma to infecting hyphae of both compatible and incompatible races of Phytophthora infestans

Aged discs of potato tuber were inoculated with incompatible race 0 and compatible race 1 of Phytophthora infestans, and then plasmolysed with hypertonic sucrose solution. Both the plasmolysed cells infected by the incompatible and compatible races showed conically shaped protoplasts, parts of which adhered to the intracellular hyphae. We named this phenomenon “tent-type plasmolysis”. Electron microscopic observation showed that many fragments of host plasmalemma adhered to the infecting hyphae, when the host plasmalemma appeared to be detached from the hyphae upon plasmolysis. These fragments adhering to the infecting hyphae seemed to be torn off from the host plasmalemma which was separated from the hyphae by plasmolysis. All these results suggested that the host plasmalemma strongly adhered to infecting hyphae of both compatible and incompatible races from the very earliest time of penetration. Tent-type plasmolyses in infected cells were also observed with petioles of potato leaves.