Two Exobasidium species causing Exobasidium leaf blister on Rhododendron spp. are described. An Exobasidium leaf blister on Rhododendron yedoense var. yedoense f. yedoense has been recognized in Hokkaido Prefecture, Japan, since the first report was issued in 1950. The causal fungus is identified with Exobasidium dubium from the morphology of its hymenial structure and mode of germination of the basidiospores. Another Exobasidium leaf blister on Rhododendron dauricum has been observed in Hokkaido Prefecture, Japan. In comparison with morphology based on hymenial structure and mode of germination of the basidiospores of the 100 validly described taxa, this fungus differs from those known taxa in the size of basidia and basidiospores, the numbers of sterigmata and septa of basidiospores, and the mode of germination of basidiospores. Thus, a new species, Exobasidium miyabei, is established and illustrated.

The gene lccK encoding a laccase of the white-rot basidiomycete Pleurotus ostreatus wild-type strain collected in Japan has been cloned, sequenced, and characterized. The isolated gene consists of 2929 bp with the coding region interrupted by 19 introns and flanked by an upstream region in which putative CAAT and TATA elements were identified. Two putative N-glycosylation sites and four putative copper-binding sites found in other fungal laccase are conserved in lccK. The cDNA contains an open reading frame of 1599bp and the gene encodes 533 amino acids preceded by a signal peptide of 23 amino acids. The nucleotide sequence of the lccK cDNA showed high homology with those of laccases of other basidiomycetes.

Analysis of isozymes was carried out against wild and cultivated commercial stocks of Flammulina velutipes to analyze their genetic differences. Esterase isozymes from F. velutipes showed many bands and variations among the different stocks on the gel. The stocks of F. velutipes in Japan were largely classified into three groups (tentatively named groups A, B, and C) according to the cluster analysis of esterase isozymes. Some characteristics of the three groups were examined. Group C was characterized by a larger spore size, slower spawn running, and a paler pileus color than groups A and B. Furthermore, group B showed a smaller spore size, slower spawn running, and paler pileus color than group A.

The D1/D2 regions of the large subunit (LSU) rRNA genes of 65 strains of Monascus and Xeromyces were PCR amplified and sequenced in both directions. Maximum-parsimony analysis produced five most parsimonious trees. The strict consensus tree of these five parsimonious trees clustered M. eremophilus, M. ruber, M. pilosus, M. purpureus, and M. sanguineus in the same clade, reflecting high sequence similarity. M. sanguineus, M. purpureus, M. ruber, and M. pilosus differed in one or two nucleotides. The sequence of M. eremophilus ATCC 62925 isolated from a xerophilic environment differed from M. purpureus in only one nucleotide, despite pronounced morphological and ecological differences when compared with the other species. M. lunisporas, M. floridanus, M. pallens, and X. bisporus were each placed in a separate branch, confirming their taxonomic descriptions as individual species. Maximum-likelihood analysis on the same data set generated a single tree and grouped the species of the first clade in the parsimony analysis into a single clade but placed the rest of the Monascus species and Xeromyces bisporus on different branches. The trees inferred from both analyses revealed a monophyletic relationship between Monascus and Xeromyces, when compared with other related cleistothecial or imperfect genera.

A sporeless mutant dikaryon, completely defective in sporulation, was isolated from mycelial protoplasts of Pleurotus eryngii mutagenized by UV irradiation. Newly established dikaryons between one component monokaryon from the mutant, and 12 different wild type monokaryons from 3 other wild type dikaryons, all exhibited the sporeless phenotype, whereas those between the other monokaryon and the same wild type monokaryons all produced normal fruiting bodies. These results indicated that the sporeless mutation was induced in one of two nuclei of the mutant and was dominant. In the wild type basidia, the pattern of nuclear behavior during sporulation corresponded to the pattern C nuclear behavior as defined by Duncan and Galbraith. Cytological observation revealed that in the sporeless mutant meiosis was blocked at the meta-anaphase I in most basidia and hence basidiospores and sterigmata were not produced. Although fruiting bodies of the sporeless mutant showed a somewhat leaning growth, their gross morphology and its fruiting body productivity were comparable to that of the original wild type strain. Based on these results, it was considered that the sporeless mutant could serve as a potential material in breeding of sporeless P. eryngii commercial strains.

Changes in litter quality resulting from pretreatment of leaf litter by phyllosphere fungi may affect its subsequent decomposition by succeeding fungi. The purpose of this study is to clarify the effect of prior decomposition of leaf litter by two phyllosphere fungi of beech, Xylaria sp. and Ascochyta sp., on substrate utilization of 12 fungal species in the Basidiomycota, the Ascomycota, and the Zygomycota, in a laboratory experiment. Mycena sp. caused significantly higher weight loss in litter previously partly decomposed by Xylaria sp. than in control litter without fungal inoculation and litter previously partly decomposed by Ascochyta sp., whereas prior decomposition retarded litter decomposition or had no significant effect on 11 other species. Prior decomposition by phyllosphere fungi affected the substrate utilization patterns of two Mycena species in the Basidiomycota, shifting from simultaneous removal of lignin and carbohydrates to selective delignification.

Eleven isolates of a species of Colletotrichum were collected from eight plant species (Crinum asiaticum var. sinicum, Passiflora edulis, Cucumis melo, Cymbidium sp., Clivia miniata, Cattleya sp., Prunus mume, and Dendrobium kingianum) at six locations on the Pacific Coast of Japan. Although the fungus had been once identified as Colletotrichum gloeosporioides sensu lato, it was clearly different from C. gloeosporioides sensu stricto in its wide conidia [l/b ratio: (1.8–) 2–3 (–3.3)], having a hilum-like conidial base and cream- to orange-colored colonies on PDA. The intraspecific DNA homologies of the ITS1 sequence were 96.9%–100%, but interspecifically 80.2%–82.3% with C. gloeosporioides. Based on the morphological and molecular characterization, the fungus is proposed as a new species, Colletotrichum boninense.

Woody substrates were collected from the Koito River in Japan, and the biodiversity of fungi on these substrates was investigated. Twenty-eight species were identified, comprising 12 ascomycete and 16 anamorphic taxa. The common fungi included Chaetosphaeria sp., Ophioceras commune, Pseudohalonectria lignicola, and Savoryella lignicola. The occurrence of fungi on submerged wood is discussed, and three interesting taxa – Pseudohalonectria lignicola, Bactrodesmium arnaudii, and B. pallidum – are described and illustrated.

Chlamydospores of Entoloma clypeatum f. hybridum were described on the mycorrhizas and rhizomorphs associated with Rosa multiflora. Their developmental pattern seems to be the Nyctalis type. This is the first report on chlamydospore formation on the mycorrhizae in entolomatoid fungi.

Monotropoid mycorrhiza formation and its morphological characteristics on an achlorophyllous plant, Monotropastrum globosum f. roseum, were investigated. The forma formed typical monotropoid mycorrhizae, indicating that the forma is myco-heterotrophic. Morphological characteristics of the mycorrhizae and root systems of the forma were quite different from those of Monotropastrum globosum, suggesting that further investigation on host specificity and the phylogeny of the plants should be conducted.

The karyotype of Flammulina velutipes (Curt. : Fr.) Sing. was investigated using contour-clamped homogeneous electric fields (CHEF) gel electrophoresis. A parental dikaryotic stock, JA, was resolved into at least eight chromosomal DNA bands ranging from 1.4- to 4.9-megabase (Mb) pairs. Overall, little size variation was found among monokaryotic strains with a few major exceptions. Among 13 monokaryotic progenies examined, 11 strains were resolved into at least eight chromosomal DNA bands in a manner similar to the parent dikaryon, whereas the other 2 were resolved into at least seven chromosomes lacking the 2.1-Mb chromosome possessed in the former. A slightly larger size variation was found in a chromosome carrying ribosomal DNA. An estimated haploid genome size of this stock was 24.0Mb or more.

We describe the effects of trehalose on spawn storage in a home freezer (average temperature, 16°C) where edible fungi usually do not survive. When the mycelia of Lentinula edodes were stored in a freezer for 3 days, the survival rate of mycelia cultivated on 2% glucose medium was 30%, whereas those on media containing 2% and 5% trehalose were 50% and 60%, respectively. Addition of trehalose to the culture was more effective in Pleurotus ostreatus. These results suggest that trehalose played the role of a stress protectant against freezing, because the mycelia cultured on a trehalose medium grew more rapidly and produced more fruiting bodies compared to those cultured on glucose.