Eiji Tanaka

We evaluated biodegradable plastic (BP) degradation abilities of various smut fungi (Ustilaginomycotina), including 8 isolates from 6 species of Ustilaginales, 3 isolates from 2 species of Exobasidiales, 7 isolates from 5 species of Tilletiales, and 3 isolates from 3 species of Microbotryales belonging to the anther smut fungi (Pucciniomycotina). The BP-degrading abilities of these fungal isolates were compared to that of a known BP-degrader, Moesziomyces antarcticus JCM 10317. The BPs tested were polycaprolactone (PCL), polybutylene succinate adipate (PBSA), polybutylene succinate (PBS), and polylactic acid (PLA). BP-degrading ability was quantified by measuring the clear zones produced by fungi on BP-containing media at temperatures from 10 ℃ to 30 ℃. The experiments revealed 10 isolates from 7 species capable of degrading PBSA and PCL, and 7 isolates from 4 species capable of degrading PBS. No isolates degraded the PLA. Notably, the PBSA-degrading ability of one isolate of Ustilago trichophora was significantly higher than that of JCM 10317 at low temperature. However, JCM 10317 was superior at degrading PCL and PBS. Our results indicate that smut fungi are potentially valuable sources of isolates with superior BP-degrading ability.

Flowering of Henon bamboo (Phyllostachys nigra var. henonis) was observed in Japan in 2020s. We estimated that the observation of flowering was recorded for the first time in 120 y. Additionally, stromata of Aciculosporium take have also been observed in the flower buds, or spikelets, of Henon bamboo. Aciculosporium take usually forms stromata at the vegetative shoot apex, which presumably originated from ancestral pathogens affecting floral tissues. However, given the infrequent occurrence of bamboo flowering events, it is unclear whether A. take still retains the ability to colonize ovaries of flowers. To ascertain the location where the fungus forms stromata, anatomical and histological analyses were performed. Because flower buds, including floral organs, are fragile, tissue sections were prepared by adhering them to cellophane tape, and subsequently examined using a triple fluorescent staining method. The findings showed that the fungus did not invade the ovaries but formed stromata from the apical rudimentary floret within the flower buds.

Ergot fungi produce toxic sclerotia that have significant impacts on the agricultural, food and pharmaceutical industries. These fungi were classified in various genera (such as Sclerotium clavus, or Spermoedia clavus) before Tulasne, in 1853, erected Claviceps and described three species based on variations in morphology and host ranges, viz. C. purpurea, C. microcephala, and C. nigricans. Since then, knowledge regarding the biological, clinical, and pharmaceutical perspectives of ergot has accumulated rapidly. However, a serious taxonomic examination was lacking until Langdon’s revision accepted 25 species in 1952. That was followed by intensive regional studies by Loveless in the 1960s for Rhodesia (now Zimbabwe, Africa), and Tanda in Japan (1970s–1990s). More species names were reported and currently over 90 named taxa (species, varieties) are recorded in fungal name repositories (Mycobank and Index Fungorum). Most species were described based on morphological characteristics (sclerotia, ascomata and conidia) and host ranges. Some were characterized by their alkaloid profiles. Recently, DNA multi-locus sequence analyses (MLSA) were applied to resolve species complexes. For instance, the C. purpurea complex was separated into four species, and additional new species were recognized from South Africa and Canada. Infra- and supra-specific level genetic variations were identified via multi-locus and genomic studies. Based on five-locus phylogenies, Píchová and colleagues separated Claviceps into four sections: C. sect. Claviceps, C. sect. Citrinae, C. sect. Paspalorum and C. sect. Pusillae, for 60 species. Among these sections, several doubtful species names require clarification. Careful research on type specimens combined with molecular analyses is essential for clarifying these names.

The genus Aciculosporium (Clavicipitaceae, Hypocreales, Ascomycota) was established in 1908 for A. take, which is the causal fungus of witches’ broom of bamboo. Although the original description was valid at that time, a type specimen for A. take has not been designated. To standardize the use of this genus and species name, a neotypification and reference specimen of A. take is are proposed. Multilocus phylogenetic analyses based on DNA sequences from 28S rDNA, TEF, Tub2, Mcm7, and RPB2 revealed that A. sasicola is from a different lineage to A. take, and other material specimens from wavyleaf basket grass (Oplismenus undulatifolius) represent a distinct species proposed here as Aciculosporium oplismeni sp. nov. Chemical analysis using mass spectrometry and nuclear magnetic resonance spectroscopy, etc. showed that A. take produces four proline-containing cyclic dipeptides, which are moieties of ergot alkaloids, . although However, ergot alkaloids, lolines, peramine, indole-diterpenes, and lolitrem were not detected in the culture solvent. The presentis study offers clarification of the lineage and morphology of this genus.

A fungus causing false smut in the flowers of Murdannia keisak (Commelinaceae, Commelinales, Monocots) in Japan was morphologically identical to Ustilago aneilematis. The fungus infected ovaries of most flowers of host plants. Infected flowers were filled with yellow to orange thick-walled conidia that became olivaceous green at maturity. However, multilocus phylogenetic analysis of DNA sequences (18S, 28S, translation elongation factor 1α [TEF], the largest [RPB1] and the second largest [RPB2] subunit of RNA polymerase II) showed that the fungus belonged to the tribe Ustilaginoideae (Clavicipitaceae, Hypocreales, Ascomycota). Microscopic examination showed that the fungus developed conidia at the apex of conidiogenous cells, in contrast to other species in the Ustilaginoideae that develop conidia pleurogenously. A new genus, Commelinaceomyces, is formally proposed in the Ustilaginoideae to accommodate this fungus. Four species previously misplaced in Ustilago (Ustilaginales, Basidiomycota) are transferred to Commelinaceomyces, including the type of the genus, C. aneilematis, on Murdannia keisak. This is the first report of a clavicipitaceous species infecting host plants in the Commelinaceae.

We aimed to develop an artificial membrane system to observe the infection process of the obligate biotrophic powdery mildew fungi without the use of living plant cells. The conidia of Blumeria graminis and Erysiphe pisi conidia were inoculated on a formvar membrane laid on an artificial medium. Germinated conidia frequently formed appressoria and then penetrated the membrane to form haustorium-like structures in the artificial medium. Secondary hyphae elongation was also observed after the formation of haustorium-like structures. These results suggested that the formvar membrane laid on artificial medium induced the formation of haustorium-like structures that have roles in the formation of secondary hyphae.

The basidiomycetous yeast Moesziomyces antarcticus (often cited as Pseudozyma antarctica), originally isolated from a sediment sample obtained from Lake Vanda in Antarctica, was asexually typified but closely related to the smut fungus Moesziomyces bullatus (Ustilaginales). We found a smut fungus on an ovary of barnyardgrass (Echinochloa crus-galli) in Japan, which had been identified as M. bullatus. The teliospores germinated and formed yeast-like colonies. Physiological and phylogenetic studies revealed that the characteristics of the yeast-like isolates coincided with those of “P. antarctica.” We thus recognised the smut fungus as the teleomorph of M. antarcticus, and then emended the description of M. antarcticus based on the holomorph. The identified fungus could degrade certain biodegradable plastics and produce mannosylerythritol lipids (MELs) in similar qualities as the “P. antarctica” type strain. This discovery provides a significant bioresource, as genetically diverse M. antarcticus isolates could be obtained from the smut fungus.