Species with narrow niche breadths are assumed to be more susceptible to environmental changes than those with wide niche breadths. Although information on niche properties is necessary for predicting biological responses to environmental changes, such information is largely missing for soil microbes. In this study, we present the temperature niche positions and breadths of a functionally important group of eukaryotic soil microbes, ectomycorrhizal (EM) fungi. We compiled high-quality EM fungal sequence data from 26 forested sites in Japan (with mean annual temperatures ranging from 1.6 to 23.6°C) to create temperature niche profiles for each individual fungal species. Nested theory and a newly developed weighted-randomization null model were applied to 75 fungal operational taxonomic units (OTUs) with high occurrence records to examine potential preferences for certain temperature positions and breadths. Our analyses revealed that (a) many EM fungal OTUs were restricted to habitats with low mean annual temperatures, (b) fungal OTUs observed at colder sites exhibited narrower temperature breadths than expected by chance, (c) the composition of EM fungal OTUs exhibited a nested pattern along the temperature gradient, and (d) EM fungal richness was highest at colder sites, where the greatest degree of overlap in OTU occurrence was observed. These findings imply that future warming may limit the distribution of many EM fungal species that are currently adapted to only cold climates. This could eventually reduce EM fungal biodiversity, which is linked to forest function through symbiotic associations with trees. This study demonstrates the distribution and environmental ranges of various EM fungal species and can contribute to develop species distribution models with the aim of conserving microbes in the face of climate change.

Trunk rot poses a substantial threat to Sanbu-sugi, one of the most economically important cultivars of Japanese cedar (Cryptomeria japonica). The etiology of this disease, including its main agents, is incompletely known. This trunk rot was attributed to Fomitiporia (Phellinus) hartigii or F. (Phellinus) punctata. Here we phylogenetically analyzed DNA sequences of four markers from a set of strains isolated from trunk-rot symptoms and recovered a single, monophyletic clade, indicating that a single taxon is involved. This clade was identified as Fomitiporia torreyae, a species described from eastern China. This analysis also proved that trunk rot and/or dieback of other conifers and broadleaf trees, including Sawara cypress (Chamaecyparis pisifera), Japanese umbrella pine (Sciadopitys verticillata) and Japanese pear (Pyrus pyrifolia var. culta), were caused by the same species. The phylogenetic approach to Fomitiporia revealed that the F. torreyae clade was closely related to F. bannaensis but clearly distinct from F. punctata, which originally was thought to be the cause of trunk rot in Sanbu-sugi. Fomitiporia torreyae is redescribed on the basis of more than 40 specimens from multiple hosts from Japan and China. Fomitiporia juniperina comb. nov. is proposed.

Morphology and comparative ecology of the fairy ring fungi, Vascellum curtisii and Bovista dermoxantha, on turf of bentgrass, bluegrass, and Zoysiagrass Abstract We identified the causal fungi of fairy rings as Vascellum curtisii and Bovista dermoxantha on the turf of bentgrass, bluegrass, and Zoysiagrass. Observing the fairy rings developed in the turfgrass study site in Chiba City for 5 years from 1998, V. curtisii, producing sporophores during June and November except midsummer, formed darkergreen rings than the adjacent turf and withered the three kinds of turf. B. dermoxantha produced sporophores exclusively in midsummer. The fungus formed dark green rings on the three kinds of turf but withered only bentgrass and bluegrass. The optimum mycelial growth temperature of V. curtisii was 30°C. Whereas that of B. dermoxantha ranged between 35° and 40°C. The infection test of the fungi to the seedlings revealed that V. curtisii damaged Zoysiagrass more severely than bentgrass and that B. dermoxantha was more injurious to bentgrass than Zoysiagrass.

Tricholoma matsutake is the most commercially important edible mushroom in pine forests in Japan. Tricholoma bakamatsutake and T. fulvocastaneum, species closely related to T. matsutake, occur in Fagaceae forests. We examined ectomycorrhizal (EM) formation by these Tricholoma species by in vitro synthesis among seven strains (two of T. matsutake, four of T. bakamatsutake, one of T. fulvocastaneum) and axenic plants of pine (Pinus densiflora) and oak (Quercus serrata, Q. phillyraeoides). All strains, except for one of T. matsutake, formed EM associations with both pine and oak. Plant growth and mycelial development were differently affected by EM formation depending on the plant-fungus combination.