Microfungal flora on aerial parts of a forest floor plant, Rodgersia podophylla, were studied at the forest side of a Japanese cedar plantation. From May to October, Nigrospora spp. were dominantly isolated from leaves, whereas Acremonium spp. and Fusarium spp. were dominant on stems, suggesting that the aerial part of the plants about 1m height can offer two different habitats for these dominant fungi. In September and October, we could easily discern different types of tissue on the withering leaves, i.e., brown (necrotic lesion), yellowish (border tissue between brown and green areas), and green (healthy tissue). Nigrospora spp. and Pestalotiopsis spp. were continuously isolated on the brown area as well as on green and yellowish areas. Pathogenicity of N. sacchari and P. neglecta on potted plant leaves was confirmed by inoculation. From these, the fungi of these two genera seemed to have changed from quiescent to pathogenic with leaf senescence. Sporulations by fungi of the two genera were recognized on overwintered stems. These fungi may overwinter in stems that are slow to decompose, and seem to go over to the leaves in the following spring. Thus, they could be candidates for parasites that may play an important role in decomposition of the plant.

Ten species of rust fungi (Crossopsora 2, Maravalia 1, Pileolaria 1, Puccinia 1, Ravenelia 1, Sphaerophragmium 1, Uredo 2, and Uromyces 1) are newly recorded together with six new host plants in Thailand.

A rust fungus found in Japan on Rhododendron kaempferi, R. kiusianum, and R. dauricum has previously been identified as Chrysomyxa rhododendri. Light and scanning electron microscopy of fresh and herbarium materials of the rust fungus, however, show that the spore surface morphology differs from the urediniospores of C. rhododendri, and the spores are slightly smaller. Furthermore, the DNA sequence of the 5′-end of the large subunit of ribosomal DNA differs from that of C. rhododendri by 3%. Telia have not been found; therefore, it is redescribed as a new anamorphic species, Caeoma tsukubaense. Several specimens from North Korea, Tibet, and Nepal bearing a similar rust fungus are also included in the species.

Purification and viscometric characterization of three CMCases from Polyporus arcularius were carried out. The three CMCases, I, II, and IIIa, were estimated to have molecular masses of 39.1 kDa, 36.3kDa, and 24.3kDa, respectively. The addition of cellobiose and cellooligosaccharides to the reaction mixtures of CMCase I and II inhibited viscometric endocellulase activity. Following the addition of 20 mM cellobiose, CMCase I and II activities fell to about 30%–36% of their activity in the absence of cellobiose. CMCase IIIa activity, on the other hand, increased in proportion to the increase in cellobiose or cellooligosaccharide concentration. Maximal enhancement of CMCase IIIa activity was observed following the addition of cellobiose, whereas less enhancement was observed with cellooligosaccharides spanning more than two glucoside units. The addition of 20mM cellobiose resulted in an increase greater than 500% in CMCase IIIa activity. Inhibition of CMCase I and II by cellobiose and cellooligosaccharides may be the result of competition between the substrate and the reaction products. One of the reaction products of CMCase IIIa may bind to a site other than the active site of the enzyme, thus enhancing CMCase IIIa activity.

The genomic and cDNA clones encoding the carboxymethyl cellulase (CMCase) gene (cel3A) of Polyporus arcularius were sequenced and characterized. The coding region of cel3A, composed of 1329 bp, was found to encode a polypeptide of 243 amino acids that has similarity with FI-CMCase of Aspergillus aculeatus. Expression of the cel3A cDNA in Escherichia coli led to production of a nonglycosylated protein as an active form; moreover, CMCase activity measured by the viscometric method was enhanced 4.47 times by addition of cellobiose. These results indicate that glycosylation and any modification of protein such as processing are not required for Cel3A activity.

Soybean sudden death syndrome (SDS) pathogens and dry bean root-rot pathogens were studied taxonomically, phylogenetically, and pathologically. Detailed phenotypic comparisons of macro- and microscopic features and phylogenetic analyses of multilocus DNA sequence data, including those on the nuclear ribosomal intergenic spacer region and the single copy nuclear gene translation elongation factor 1-a, indicated that they comprised five distinct species of Fusarium. Two new species causing soybean SDS in Brazil, F. brasiliense and F. cuneirostrum, are formally described. Fusarium cuneirostrum is responsible for soybean SDS in Brazil and dry bean or mung bean root-rot in the United States, Canada, and Japan. Strains of each species, including F. cuneirostrum isolates from dry bean and mung bean and F. phaseoli isolates from dry bean, were inoculated on soybean cultivar Pioneer 9492RR to determine their pathogenicity. Although intraspecific variation in pathogenicity was observed, all the species were able to induce typical SDS symptoms on soybean plants in the artificial inoculation tests. Comparisons of the key diagnostic morphological features reveal that all five species can be diagnosed using conidial morphology.

Six Inocybes are described and illustrated as new taxa or new records from Japan. A new species, Inocybe magnicarpa, is a member of section Marginatae. Two new varieties, I. malenconii var. cylindrata, a member of section Dulcamarae, and I. brunneorufa var. angusta, a representative of section Marginatae. Inocybe reisneri (section Rimosae) and I. fuscidula (section Tardae), are recorded as new to Japan. Inocybe pseudodestricta (section Tardae) is redescribed from a new locality (Chiba Prefecture). They are compared with similar taxa.

A yeast strain isolated from insect frass collected in Thailand was found to represent a new species of the genus Pichia. It is described as Pichia nongkratonensis sp. nov. In the phylogenetic tree based on the D1/D2 domain sequences of 26S rDNA, this yeast constitutes a cluster with Pichia dryadoides with high bootstrap confidence level; however, it differs from the latter species by 5.6% base substitutions. Pichia nongkaratonensis resembles P. dryadoides also in the phenotypic characteristics but is distinguished from this species by the assimilation of several carbon and nitrogen compounds.

Three species of Tetraploa collected from Sasa, or bamboos, are described and illustrated. Among them, T. curviappendiculata on Sasa kurilensis and T. longissima on Pleioblastus chino are compared with hitherto known species and described as new species. In the nomenclature, T. javanica is substituted for T. biformis, formerly reported from the dead bark of a broad-leaved tree in Japan, as a correct name.

Interaction between arbuscular mycorrhizal fungus Glomus mosseae and plant growth promoting fungus Phoma sp. was studied for its effect on their root colonization and plant growth of cucumber. Two isolates of Phoma sp. (GS8-2 and GS8-3) were tested with G. mosseae. The percent root length colonized by G. mosseae was not adversely affected by the presence of Phoma isolates. In contrast, the root colonization of both isolates GS8-2 and GS8-3 in 4-week-old plants was significantly reduced (80.7% and 84.3%, respectively) by added G. mosseae. Inoculating plants with each Phoma isolate significantly increased the shoot dry weight. However, dual inoculation of each Phoma isolate with G. mosseae had no significant effect on growth enhancement.