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.

Three species of Ophiostoma possessing Pesotum anamorphs isolated from bark beetles and their galleries infesting Abies species in Nikko, Japan, are described as new species. Ophiostoma nikkoense is characterized by brush-shaped synnemata producing long septate clavate conidia, perithecia with neck, and allantoid ascospores. Ophiostoma microcarpum has smaller perithecia with hyphoid ostiolar hyphae on the neck, and the ascospores are cylindrical or ossiform in side and face views. Ophiostoma abieticola has perithecia without ostiolar hyphae on the neck and produces orange-section-shaped or reniform ascospores.

The activity concentration of 131I, 134Cs and 137Cs radionuclides in lichens was traced one and a half months after the Fukushima nuclear accident. The samples were collected in Tsukuba City, which is located c. 170 km south of the Fukushima Daiichi nuclear power plant (NPP). The activity concentrations differed depending on species and habitat. For example, the maximum activity concentration of 137Cs was 22596 Bq kg–1 dry weight in Physcia orientalis (collected from the trunk of Zelkova serrata on 30 June 2011), and 1928 Bq kg–1 in Hyperphyscia crocata (from the trunk of Quercus myrsinaefolia collected on 8 March 2012). The activity concentration of 137Cs in Dirinaria applanata and Phaeophyscia spinellosa growing on vertical habitats decreased by c. 50% within a year, indicating radionuclides might have been washed off by rain. The radionuclides were apparently derived from the Fukushima NPP accident because: 1) one specimen collected at the same place one year before the accident did not contain radionuclides, 2) high activity concentrations of radionuclides were detected after the accident, 3) 131I, which has a short half-life of 8 days, was detected one and a half months after the accident, and 4) the ratio of 134Cs/137Cs in lichens was 0·90–0·98 on 26 April 2011, which is consistent with the values reported for radiocesium from the Fukushima NPP accident.

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