High-pressure freezing and freeze substitution fixation of the plant pathogenic fungus Exobasidium vaccinii
Members of the small fungal genus Exobasidium are all plant pathogens. Most species are noted for their ability to produce large fleshy galls on leaves and flower parts. They produce their hyphae and specialized absorbing structures known as haustoria inside these galls and their sexual reproductive structures (basidia) on gall surfaces. The objective of this study was to examine the feasibility of using high pressure freezing (HPF) followed by freeze-substitution (FS) fixation to prepare Exobasidium induced galls on Rhododendron sp. for study with transmission electron microscopy (TEM). HPF fixation followed by FS fixation is considered to be the best method for preserving large samples of plant tissue for TEM. This approach has shown promise for the examination of host-pathogen relationships in fungal diseases of plants.