A survey was conducted on soil-borne teleomorphic Aspergillus, namely Emericella, Neosartorya and Petromyces, from 98 areas in Asia, Middle and Near East and South America. For the 316 isolates assigned to 30 species and 2 varieties of Emericella, the ability to produce sterigmatocystin (STG) was examined by HPLC. As a result, the following STG producers were found: E. acristata, E. corrugata, E. dentata, E. echinulata, E. falconensis, E. foveolata, E. heterothallica, E. nidulans, E. nidulans var. lata, E. parvathecia, E. purpurea, E. quadrilineata, E. rugulosa, E. rugulosa var. lazulina, E. spectabilis and E. striata. For the 82 isolates assigned to 16 species of Neosartorya, 3 species of Chaetosartorya and one species of Sclerocleista the ability to produce tremorgenic mycotoxins, namely fumitremorgin A and B, and verruculogen, was examined. The following tremorgenic mycotoxins producers were found: N. aurata, N. botucatensis, N. fennelliae, N. fischeri, N. glabra, N. hiratsukae, N. quadricincta, N. stramenia and N. udagawae.

　Examinations of spermogonia of many genera and species of rust fungi revealed that morphological types can clearly be divided into 12, and if the positions of spremogonia in the hosts are disregarded, 6 groups. Morphological types of spermogonia strongly indicate phylogenetic relationships among rust fungi. Considering the spermogonial types as important taxonomic criteria, 14 families (later reduced to 13) have been recognized including two new families (Micronegeriaceae and Chaconiaceae). Two pine-to-pine stem rusts, one in the North America and another in Europe, have been proven by repeated inoculation experiments and cytological observations, to have endocyclic life cycles. A new genus Endocromartium has been established to accommodate the two species. Criteria of terminology of spore states of the rust fungi should be based on the positions in the life cycles and not according to their morphological types. Thirteen (13) anamorphic genera, including a new genus (Petersonia), have been redefined and recommended to be used in combination with ontogenically defined spore state names. Use of terms such as aecia Aecidium-type, uredinia Uredo-type, aecia Uredo-type, uredinia Aecidium-type, aecia Milesia-type and telia Peridermium-type are recommended.

　Photomorphogenesis of basidiomycetes was studied. Polyporus arcularius (Favolus arcularius) needs light for primordium and pileus-primordium formation. These photomorphogenetic events in this fungus involved similar photomorphogenetic processes: two essential light processes and an intervening dark process. The nature of these elementary processes in pileus-primordium formation was examined by the use of high temperature treatment (37°C-15min), which disrupted the photomorphogenetic process without any aftereffects. The action spectra for primordium and pileus-primordium formation were determined and the nature of blue light photoreceptor was discussed. The regulation of carbohydrate and nitrogen metabolism, especially on trehalose metabolism, in fruit-body formation of basidiomycetes, was also studied. Flammulina velutipes involves glycogen and trehalose as storage and translocates carbohydrate as is common to other mushrooms. The author and his co-workers found a novel key enzyme, α-glucose 1-phosphate (α-G1P), forming trehalose phosphorylase (TP), which regulated trehalose metabolism in basidiomycetes. TP was purified from Pleurotus ostreatus, and the holoenzyme was estimated to be a dimer of two identical subunits. TP regulated the synthesis of trehalose in mycelium and the phosphorolysis of trehalose to produce α-G1P and glucose in fruit-bodies. Complementary DNA for a gene encoding TP (PsTP) was cloned from Pleurotus sajor-caju. The PsTP gene is expressed in mycelium and fruit-bodies.

　For the purpose of discovering new bioactive metabolites, a wide range of basidiomycetes, including members with minute basidiocarps which have been underutilized for microbial screening, were collected and isolated. As a result of screening, six novel bioactive metabolites were found. Two of them were found from minute basidiomycetes. Taxonomic study of minute basidiomycetes revealed two new species and two species new to Japan. In addition, 13 taxa of Physalacria were considered to be distributed in Japan. These results suggest the existence of diverse flora of minute basidiomycetes in Japan, such basidiomycetes being promising biological resources for the future.

　To understand the effects of vegetation changes and soil conditions on ectomycorrhizal fungi, the quality and types of ectomycorrhizas of Betula platyphylla var. japonica seedlings planted in soils taken from various sites were studied. The soils were collected from naturally regenerating birch stands: four 50-year-old forest sites which had different types of forest floor vegetation, a clear-cut site, and five sites recently disturbed by the removing of surface soil. Soils from the site of an evergreen broad-leaved forest and an artificial plantation of Chamaecyparis obtusa forest without birch were also used. The results of this investigation showed that the different ectomycorrhizal fungi were better adapted to the host plant and the soil conditions in each sampling site. Under an aseptic culture condition, effects of the dominant ectomycorrhizal and dark septate endophytic fungi at the recently disturbed sites on the growth of B. platyphylla var. japonica seedlings were investigated. The results showed that the dominant ectomycorrhizal fungi have a beneficial effect on the growth and suppress the deleterious effect of dark septate endophytic fungi for B. platyphylla var. japonica seedlings. Some ectomycorrhizal fungi would have an important role for establishment of B. platyphylla var. japonica seedlings, especially at the initial stage of re-vegetation following destructive forest disturbance. A certain specific ectomycorrhizal association should thus be one of the most important factors for the establishment and persistence of the pioneer plants at sites undergoing re-vegetation.