XVI International Botanical Congess

Species of Phytophthora cause many destructive plant diseases. Pathogen dissemination and plant infection are mediated by wall-less, motile zoospores which are chemotactically attracted to the roots of potential host plants. At the plant surface, zoospores secrete an adhesive which attaches them to the root, they then germinate and colonize the adjacent plant tissues. Immunocytochemical studies of the structure, development and function of Phytophthora zoospores have not only contributed t our understanding of fundamental aspects of plant and fungal cell biology, but may also provide the basis for the development of novel strategies for disease control. Aspects of immunolabeling studies that will be described include (1) localization of stores of adhesive material in zoospores, (2) characterization of storage protein reserves used to support early colonization of the plant, (3) identification of flagella surface proteins responsible for forward movement of the zoospores, and (4) demonstration of the presence of vacuolar H+ -ATPase in a membrane system which functions in zoospore osmoregulation.