HOST-PARASITE INTERFACES IN A RESISTANT AND A SUSCEPTIBLE CULTIVAR OF SOLANUM-TUBEROSUM INOCULATED WITH PHYTOPHTHORA-INFESTANS - TUBER TISSUE

Host-parasite interfaces in potato tubers (S. tuberosum) of a resistant (''Eba'') and a susceptible (''Bintje'') cultivar inoculated with P. infestans were studied with transmission EM. In the resistant host the fungal haustoria are typically small and surrounded by an electron-dense extrahaustorial matrix and electron-transparent wall appositions, normally in form of complete encasements. Wall appositions are generally lacking in the susceptible host or occasionally are found as a collar at the base of the rather large haustorium, which is surround by a well developed extrahaustorial matrix. Since wall appositions probably contain largely a callose-like material, potential roles of fungal glucanases in this host-parasite system are discussed.