Ultrastructure of the Host-Parasite Relationships of Pseudoperonospora humuli on Hops

Abstract

Infected leaf tissue was examined at 3, 4, 5 and 6 days after inoculation, after different fixing and staining techniques. One example of stomata1 penetration was seen. Examples of cell penetration and haustorium development were examined in detail. Haustoria penetrate host cells by altering host cell wall structure, and lomasomes are frequently present in the haustorium neck. Haustoria do not have nuclei and in early stages have abundant mitochondria that gradually decrease in number as infection advances.