Endophytic fungi from the mycorrhizae of alpine ericoid plants

Strains of a slow-growing, sterile, darkly pigmented fungus were obtained from alpine mycorrhizae of the Alberta Rocky Mountains. Sporulating isolates of this fungus from the roots of Cassiope mertensiana and Arctostaphylos uva-ursi (Ericaceae) as well as from Luetkea pectinata (Rosaceae) were identified as Phialocephala fortinii. Axenic cultures of Menziesia ferruginea (Ericaceae) seedlings were grown with P. fortinii for characterization of the fungus–root association. Typically, dark, simple septate hyphae form extensive wefts on the root surface and produce intracortical sclerotia of compact, darkly pigmented and irregularly lobed, thick-walled hyphae. Intracellular coils are not produced. This association differs from the ericoid mycorrhizal type and represents a fungus–root association that is common in alpine plants. In addition, several isolates of Oidiodendron griseum, a species previously reported from mycorrhizae of ericaceous plants, were found to form intracellular coils within the cortical root cells of Loiseleuria procumbens (Ericaceae).