Fungal Communities of Sclerotia Grains from Forest Soils

Sclerotia, tentatively identified as the resting bodies of Cenococcum geophilum, were obtained from cool-temperate forests on Mt. Chokai and Mt. Iwaki in northern Japan and on Mt. Ontake in central Japan, to survey sclerotia-associated fungi and attempt to identify which fungi produced the sclerotia. The sclerotia-associated fungal communities were surveyed using terminal restriction fragment length polymorphism analysis combined with construction of a clone library using the internal transcribed spacer region of ribosomal DNA. Sclerotia were also cultured, and resulting fungal colonies were identified. Fungi associated with sclerotia from Mt. Chokai and Mt. Iwaki were predominantly Arthrinium arundinis and Inonotus sp., respectively. These sclerotia-associated species either formed the sclerotia, attacked and colonized C. geophilum sclerotia, or occupied inviable sclerotia originally formed by C. geophilum. Sequencing of the clone library generated from the Mt. Ontake sclerotia suggested that C. geophilum was present among the isolated fungi, which were mostly ascomycetes. Although C. geophilum could not be cultured from the sclerotia, three dark septate endophytes, none of which could be identified, formed sclerotia in culture. Thus, the sclerotia examined in this study might have been formed either by C. geophilum or by other fungal taxa.