Diversity of ericoid mycorrhizal fungi isolated from hair roots of Rhododendron obtusum var. kaempferi in a Japanese red pine forest

Abstract

The diversity of ericoid mycorrhizal fungi of Rhododendron obtusum var. kaempferi was examined in a stand of Pinus densiflora at Tsukuba, Japan. In total, 153 slow-growing fungal isolates were obtained from roots of R. obtusum var. kaempferi, in which 113 isolates formed an ericoid mycorrhizal structure in vitro. Among them, 53 isolates were morphologically identified as Oidiodendron maius, but the others were not identified due to their sterilities. PCR-RFLP analysis in the rDNA-ITS region divided them into four different RFLP types. Phylogenetic analysis from sequence data of the region suggested that the four RFLP types belonging to distinct taxa and one sterile type are considered to be Hymenoscyphus ericae. This study is the first report of ericoid mycorrhizal fungi in a natural habitat in Japan.