Language：English   Publishing type：Research paper (scientific journal)  

Metarhizium Sorokīn (Hypocreales: Clavicipitaceae) is a genus of facultative parasites of insects found in soils from various environments and is used for pest management. Understanding the habitat selection of Metarhizium spp. is critical to improve the efficacy and persistence of these fungi as microbial insecticides. This study sought to determine the habitat preferences of Metarhizium spp. in Japan. We identified 302 isolates of Metarhizium spp. as eight species by a combination of PCR–RFLP and phylogenetic analysis of DNA sequences. M. pingshaense was the predominant species in Japan and was most frequently isolated from both forest and agricultural environments. On the other hand, M. brunneum and M. pemphigi were comparatively restricted to forest environments. A similar species association was detected in a small area that was intensively investigated, where 7 species including 14 genotypes were isolated from soil. The results of this study have revealed different habitat preferences among Metarhizium spp. in Japan.

DOI： 10.1080/21501203.2017.1386244

Language：English   Publishing type：Research paper (scientific journal)  

Some isolates of Metarhizium anisopliae sensu lato with large conidia (MALC), which was formerly known as M. anisopliae var. majus, from a scarabaeid host, such as isolates from the coconut rhinoceros beetle (Oryctes spp.), have a narrow host range and are particularly adapted to their original host. Despite recent taxonomic revisions of the genus Metarhizium on the basis of DNA sequences, variations in host preferences of MALC have not been linked to DNA sequence variations. This study focused on the phylogenetic status and pathogenicity of MALC isolated from the fruit beetle larva Protaetia orientalis submarumorea (Pos) in Japan to investigate the relationship between virulence and nucleotide sequence variation among MALC. On the basis of the results of the phylogenetic analyses of DNA sequences from five loci, we identified an isolate from Pos (Hn1) as M. majus, which comprised many isolates with large conidia from scarabaeid insects. In the virulence assay of genetically diverse Metarhizium isolates, only Hn1 and its most closely related isolates from soil showed pathogenicity to Pos; however, these Pos-pathogenic isolates showed weak virulence against silkworms. In the analysis of the intergenic spacer region of rDNA, the Pos-pathogenic isolates displayed unique sequence variation and were clearly distinguished from closely related lineages, including isolates from Oryctes sp., which formed a separate monophyletic group. These results indicate that the Pos-pathogenic isolates from Japan are particularly adapted to Pos and can be genetically distinguished from M. majus isolates from different scarabaeid insects.

DOI： 10.1007/s11557-015-1082-7

Language：English   Publishing type：Research paper (scientific journal)  

The knowledge of the growth characteristics of entomopathogenic fungi at different temperatures is very important for understanding their ecology and field efficacy as biological control agents. However, the relationships between their DNA-based phylogenetic tree classifications and growth characteristics at different temperatures have not been adequately investigated. In this study, we compared the phylogenetic relationships between Metarhizium anisopliae sensu lato and M. flavoviride isolates obtained from soils in various environments in Japan and the germination rates of their conidia on agar medium in hot and cold conditions. The results showed that the 89 Japanese isolates belonged to the clade of eight species, according to the molecular phylogenetic analysis. The germination rates of isolates belonging to the M. brunneum and M. flavoviride var. pemphigi clades were higher at lower temperatures (9·7-11·0°C) and lower at higher temperatures (34·3-35·2°C) compared with the other six species. The isolates of these two species originated from different geographical regions in Japan, despite their uniform germination characteristics. This study detected the clear interspecific differences in the in vitro germination characteristics of the Japanese isolates of Metarhizium spp. at two different temperature regimes.

DOI： 10.1111/lam.12150

Language：English   Publishing type：Research paper (scientific journal)  

As a result of analyzing the internal transcribed spacer (ITS) and 5′ end of the EF-1α sequence of 145 isolates of Metarhizium spp. isolated from soil in Japan using selective agar medium, eight species were identified. ITS sequence analysis divided the isolates into three clades. Two were identified as M. flavoviride var. pemphigi and M. lepidiotae, respectively. EF-1α sequence analysis identified the other clades as six species: M. anisopliae, M. brunneum, M. guizhouense, M. majus, M. pingshaense and M. robertisii. The distribution of M. flavoviride var. pemphigi was restricted to forest or wood soil, and conidial sizes of M. guizhouense and M. majus were incongruent with the phylogeny based on the sequence of the 5′ end of EF-1α.

DOI： 10.1007/s13355-011-0045-y

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers in Plant Science  

The entomopathogenic fungus Beauveria bassiana is used commercially as a microbial insecticides against a wide range of agricultural insect pests. Some strains of B. bassiana protect the plants from pathogens, but the underlying mechanisms are largely unknown. Here, we found that prophylactic sprays of commercial bioinsecticide Botanigard on cucumber, tomato, and strawberry plants suppressed the severity of economically damaging powdery mildews. On leaf surfaces, hyphal elongation and spore germination of cucumber powdery mildew, Podosphaera xanthii , were inhibited, but B. bassiana strain GHA, the active ingredient isolated from Botanigard, only inhibited hyphal elongation but had no effect on spore germination of P. xanthii . In addition, strain GHA suppressed powdery mildew symptoms locally, not systemically. Treatment with Botanigard and strain GHA induced a hypersensitive response (HR)–like cell death in epidermal cells of the cucumber leaves in a concentration-dependent manner and inhibited penetration by P. xanthii . Transcriptome analysis and mass spectrometry revealed that GHA induced expression of salicylic acid (SA)–related genes, and treatment with Botanigard and GHA increased the SA level in the cucumber leaves. In NahG -transgenic tomato plants, which do not accumulate SA, the biocontrol effect of tomato powdery mildew by GHA was significantly reduced. These results suggested that B. bassiana GHA induces SA accumulation, leading to the induction of HR-like cell death against powdery mildew and subsequent suppression of fungal penetration. Thus, Botanigard has the potential to control both insect pests and plant diseases.

DOI： 10.3389/fpls.2023.1211825

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Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Applied Entomology and Zoology  

Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is a serious pest of crops and vegetables in several Asian areas. Metarhizium rileyi is one of the most promising entomopathogenic fungi for controlling S. litura because of its specificity to lepidopteran larvae; however, little is known about its virulence against last instar larvae and pupae of S. litura although these stages are efficiently controlled by introducing entomopathogenic fungi into the soil. This study aimed to characterize the virulence of M. rileyi strain against the two stages of S. litura by comparing it with 13 strains of entomopathogenic fungi with broad host ranges. In inter-stage virulence comparisons, most fungal strains showed considerably stronger virulence against larvae than against pupae, with M. rileyi Nr4 showing the largest difference. Inter-strain virulence comparisons based on final mortality and mycosis proportion as well as integrative virulence scores revealed that M. rileyi Nr4 was the most virulent against larvae, whereas it was the weakest against pupae, but caused malformation in emerged adults. These results suggest that M. rileyi Nr4 is the most promising for controlling the last instar larvae and is less effective against pupae than the generalist fungi.

DOI： 10.1007/s13355-023-00824-x

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Mycology  

The entomopathogenic fungus Akanthomyces muscarius strain IMI 268317, previously known as Lecanicilliummuscariumand Verticillium lecanii, is currently used as a microbial insecticide to protect tomatoes from serious leaf-inhabiting pests in greenhouses. However, its persistence on tomato leaves has been unidentified. Understanding the events and processes of phyllosphere colonisation by this strain should help in developing its practical applications. This study assessed the epiphytic abilities of this strain on tomato leaves in humid conditions, simulating closed greenhouse environments. Conidia applied on tomato leaflets strongly adhered 12 h after inoculation. The mucilage-like materials were found around the germinated conidia after 3 days after inoculation (dpi), which possibly strengthened the adhesion. A total of 15% of conidia germinated at 3 dpi, of which 2% formed typical conidium or an enlarged structure on germ-tube tips. Many conidia were produced on phialide tips that branched from elongated hyphae at 7 dpi; however, invasion into leaf tissue was not observed. On the leaflets, inoculated conidia suspensions of 1 × 105 and 1 × 106 conidia/mL, colony forming units increased 52.6 and 8.8 folds from 0 to 14 dpi, respectively. These results suggested that A. muscarius strain IMI 268317 has high epiphytic abilities on tomato leaflets in a humid condition.

DOI： 10.1080/21501203.2021.1944929

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Scopus

PubMed

Publisher：Frontiers in Microbiology  

Fusarium oxysporum is a soil-borne fungal pathogen that causes vascular wilts in a wide variety of crops. Certain nonpathogenic strains of F. oxysporum are known to protect crops against F. oxysporum pathogens. We assessed the biocontrol activities of nonpathogenic mutants of F. oxysporum ff. spp. melonis and lycopersici generated by disruption of the FOW2 gene, which encodes a Zn(II)2Cys6-type transcriptional regulator essential for their pathogenicity. Pre-inoculation of melon or tomato roots with strain ΔFOW2 conidia markedly reduced disease incidence caused by the parental wild-type strain in a concentration-dependent manner of conidial suspensions of ΔFOW2 strains. The biocontrol effect caused by the ΔFOW2 pre-inoculation lasted for at least 7 days. Pre-inoculation of melon roots with the wild-type or ΔFOW2 strain of F. oxysporum f. sp. lycopersici and nonpathogenic F. oxysporum strain also led to biocontrol activity against F. oxysporum f. sp. melonis, indicating that the biocontrol activity of ΔFOW2 strains is due to its nonpathogenic nature, not to the FOW2 disfunction. Conidial germination and hyphal elongation of only the wild-type strain were inhibited on melon root surface pre-inoculated with conidia of strains nonpathogenic to melon plants. Expression of defense-related genes was not significantly induced in roots and aboveground parts of melon seedlings preinoculated with ΔFOW2 conidia. Carbon source competition assay showed that nonpathogenic strains competed with the wild-type strain for a carbon source in soil. Strain ΔFOW2 also competed with the oomycete pathogen Pythium aphanidermatum for carbon source and protected melon plants from P. aphanidermatum. Our results suggest that the biocontrol activity of the nonpathogenic F. oxysporum strains used in this study mainly depends on their extensive colonization of the root surface and outcompeting pathogens for nutrients.

DOI： 10.3389/fmicb.2022.826677

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Scopus

PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Beauveria bassiana, known for its entomopathogenic characteristics, is the most widely used biocontrol agent against many insect pests and may also be active against soil-borne pathogens. It inhabits the surfaces or inner tissues of various plant species without causing any visible signs or symptoms. Here we show that B. bassiana strain GHA, the active ingredient of a commercial microbial insecticide, colonises tomato plants. GHA grew on intact leaf surfaces of tomato in high humidity, but never entered stomata. Viable hyphae and conidia were detected, and the population on inoculated leaves significantly increased until 14 days after inoculation. On tomato leaves, GHA conidiated normally via conidiophores and phialides, and also via microcycle conidiation (conidiophores and phialides form directly from germ tubes and produce conidia). Hyphae were also detected inside the rachis, even more frequently after plant surfaces were scarified. These results suggested that B. bassiana strain GHA can grow epiphytically and endophytically on tomato plants.

DOI： 10.1080/21501203.2019.1707723

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jip.2020.107502

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/ppa.12916

Other Link： https://onlinelibrary.wiley.com/doi/full/10.1111/ppa.12916

Language：English   Publishing type：Research paper (scientific journal)  

Metarhizium anisopliae sensu lato is a facultative entomopathogenic, soil-inhabiting fungus that has been used for biological control of soil-dwelling arthropod pests. However, little is known about the density of M. anisopliae sensu lato in forest soils and the difference in the density among different habitat types and geographical origins. In this study, we determined the density of this fungus in soil samples collected from forest and agricultural fields in Japan by plating method with semi-selective agar medium and analyzed its associations with the habitat types and latitudes of the collecting sites. Mean and mode density of 211 soil samples were 9.4 × 10 ² CFUs/g soil and 1.0 × 10 ³ -1.0 × 10 ⁴ CFUs/g soil, respectively, which were comparable to the levels previously reported in other countries. The density in forest soil was not significantly different from that of the other habitat types, despite previous studies that concluded M. anisopliae sensu lato to be less abundant in forest soil based on occurrence determined by insect bait method. The latitude was also not significantly associated with the density. This study revealed higher abundance of M. anisopliae sensu lato in forest soil than the original expectation.

DOI： 10.5943/CREAM/8/4/6

Language：English   Publishing type：Research paper (scientific journal)  

Four housekeeping genes including gapA, groEL, gyrA and pgi were used in order to reveal a phylogenetic relationship among Paenibacillus species. Phylogenetic analysis and end-to-end pairwise analysis were carried out using nucleotide and amino acid sequences of the housekeeping genes. A monophylogenetic clade including P. popilliae, P. thiaminolyticus and P. dendritiformis formed in all phylogenetic trees. The results in both analyses indicated that the relationship between P. larvae subsp. larvae and P. popilliae was comparatively far. The result of the end-to-end pairwise analysis also showed that, among the Paenibacillus species used in this study, the closest species to P. popilliae was P. dendritiformis.

DOI： 10.11416/jibs.82.1_001

Language：English   Publishing type：Research paper (scientific journal)  

Mutation and polymorphism detection by nucleases has become a more important tool in clinical and biological researches. There are several kinds of single-stranded nucleases for detecting mismatched DNAs. One of them, CEL II, was isolated from Apium graveolens and cleaves DNA with high specificity at sites of mismatch. High-throughput mutation scanning requires large quantity of CEL II endonuclease. Here, we demonstrate high-level expression of CEL II using silkworm-baculovirus system. The recombinant CEL II secreted in silkworm hemolymph was glycosylated and susceptible to N-glycosidase F. Additionally, larger metal ions such as Ca²⁺ and Sr²⁺ were able to replace Mg²⁺ and enhanced mismatch cleavage activity of CEL II. These results indicate that the silkworm-baculovirus platform is a good alternative system to obtain the functional CEL II.

DOI： 10.1007/s00253-012-4583-1

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：農林水産技術会議事務局筑波産学連携支援センター本館（茨城県つくば市観音台2-1-9）   Country：Japan  

Event date： 2022.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン（大阪市立自然史博物館）   Country：Japan  

Event date： 2022.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：信州大学 繊維学部   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：信州大学 繊維学部   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：信州大学 繊維学部   Country：Japan  

Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：秋田県立大学   Country：Japan  

オオホシカメムシおよびヒメホシカメムシ（カメムシ目オオホシカメムシ科）は日本では本州以南に広く分布し、アカメガシワの花穂などに集まる。昆虫寄生菌は本種の主な天敵とされていなかったが、2018年7月から11月にかけて三重県津市安濃町野口のアカメガシワ林床の一区画内（およそ6 m×15 m）において、オオホシカメムシ成虫、ヒメホシカメムシ成虫、およびそのいずれかの幼虫の糸状菌感染によると思われる死体がそれぞれ75, 8, および7体発見された。死体の多くは発見時または追培養後に表面に緑色または白色の菌体の叢生が認められた。その菌体部分から分離された83菌株は形態的特徴から、80株がMetarhizium anisopliae sensu lato (s.l.)に、3株がBeauveria bassiana s.l.に同定された。M. anisopliae s.l.の分離株は全てほぼ同一の形態的特徴を有し、分生子塊はSabouraoud Dextrose寒天培地上では黄褐色、Potato Dextrose寒天培地上では暗緑色であった。同じ採集地ではゾウムシ科およびケバエ科の昆虫のM. anisopliae s.l.感染によると思われる死体がそれぞれ1および2体発見されたが、それらの分離株もほぼ同一の形態的特徴を示し、全て同一系統であることが示唆された。発表者は三重県松阪市、岡山県および福岡県でも、M. anisopliae s.l.感染により死亡したと思われるオオホシカメムシおよびヒメホシカメムシの死体を発見していたことから、この２種のカメムシは国内の広い地域でM. anisopliae s.l.に寄生されていると考えられた。今後はこれらのM. anisopliae s.l.分離株について、高宿主域タイプのMetarhizium spp.との分子系統学的関係性と寄主選好性とを明らかにする予定である。

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京農工大学小金井キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京農工大学小金井キャンパス   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：筑波大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：筑波大学   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：筑波大学   Country：Japan  

Language：English   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：島根大学（オンライン）   Country：Japan  

Type：Academic society, research group, etc. 

Type：Competition, symposium, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：10

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3