• The Plant Pathology Journal
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• 제20권2호
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• pp.103-105
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• 2004

A destructive stem rot of strawberry (Fragaria x ananassa cv. Akihime) sporadically occurred in farmers' fields in Daegok-myon, Jinju city, Gyeongnam province in Korea. The infected plants showed stem and crown rot, with occasional blighting of the whole plant. White mycelia appeared on stems of infected clones and sclerotia formed on the old lesions near soil surface. The fungus formed white colony on PDA and showed maximum mycelial growth and sclerotial formation at $30^{\circ}C$. The fungus usually have many narrow hyphal strands, 2.6-10.0 $\mu\textrm{m}$ in width, in the aerial mycelium. Typical clamp connections were formed on the mycelium. Sclerotia were spherical and 1.0-2.4 mm in size. The fungus was repeatedly isolated from infected tissues and identified as Sclerotium rolfsii. Its patho-genicity was confirmed when inoculated onto straw-berry. This is the first report on the stem rot of strawberry caused by S. rolfsii in Korea.

• Mycobiology
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• 제37권2호
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• pp.158-159
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• 2009

In 2007 to 2008, a fruit rot of Melon (Cucumis melo L.) caused by Sclerotium rolfsii occurred sporadically in a farmer's vinyl house in Jinju City. The symptoms started with watersoaking lesion and progressed into the rotting of the surface of fruit. White mycelial mats appeared on the lesion at the surface of the fruit and a number of sclerotia formed on the fruit near the soil line. The sclerotia were globoid in shape, 1${\sim}$3 mm in size, and white to brown in color. The hyphal width was measured 3 to 8 ${\mn}$. The optimum temperature for mycelial growth and sclerotia formation was 30 on PDA. Typical clamp connections were observed in hyphae of grown for 4 days on PDA. On the basis of symptoms, mycological characteristics and pathogenicity to the host plant, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of the fruit rot of Melon caused by S. rolfsii in Korea.

• Mycobiology
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• 제47권3호
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• pp.273-279
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• 2019

A new species, Pythium subutonaiense, isolated from aquatic environments (lake) in China is being described based on morphological characters and molecular evidence. The isolates grew at temperatures between $5^{\circ}C$ and $38^{\circ}C$, and the optimum temperature was $30^{\circ}C$, with a radial growth rate of 17.6 mm at $25^{\circ}C$ per day. It is homothallic and characterized by globose to sub-globose shaped and mostly terminal or sometimes catenulate hyphal swellings, filamentous non-inflated sporangia, and smooth oogonia with hypogynous and monoclinous antheridia that contained one plerotic oospore. In phylogenetic analysis, inferred based on the internal transcribed spacer region of the ribosomal RNA gene and mitochondrial cytochrome c oxidase subunit 1 gene, the new species formed a distinct lineage in Pythium clade B. Differences between the new species and phylogenetically related and morphologically similar species are discussed.

• The Plant Pathology Journal
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• 제25권3호
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• pp.205-212
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• 2009

Colletotrichum acutatum was the main cause of the recent outbreaks of anthracnose on pepper fruit in Korea. To facilitate molecular analysis of C. acutatum, we generated an arginine auxotrophic mutant of the C acutatum strain JC24 using a targeted gene replacement strategy. A 3.3-kb genomic region carrying an ortholog (designated CaARG2) of the fungal gene encoding N-acetylglutamate synthase, the first enzyme of arginine biosynthesis in fungi, was deleted from the fungal genome. The mutant exhibited normal growth only when arginine was exogenously supplied into the culture medium. Transformation of the arginine auxotrophic mutant with a plasmid DNA carrying an intact copy of CaARG2, which was smaller than the deleted region in the mutant, not only caused random vector insertions in the fungal genome, but also recovered both hyphal growth and pathogenicity of the mutant to the wild-type level. Using this new selection system, we have successfully developed a restriction enzyme-mediated integration procedure, which would provide an economically efficient random mutagenesis method in C. acutatum.

• Journal of Microbiology
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• 제44권2호
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• pp.145-154
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• 2006

Heterotrimeric G proteins (G proteins) are conserved in all eukaryotes and are crucial components sensing and relaying external cues into the cells to elicit appropriate physiological and biochemical responses. Basic units of the heterotrimeric G protein signaling system include a G protein-coupled receptor (GPCR), a G protein composed of ${\alpha},\;{\beta},\;and\;{\gamma}$ subunits, and variety of effectors. Sequential sensitization and activation of these G protein elements translates external signals into gene expression changes, resulting in appropriate cellular behaviors. Regulators of G protein signaling (RGSs) constitute a crucial element of appropriate control of the intensity and duration of G protein signaling. For the past decade, G protein signaling and its regulation have been intensively studied in a number of model and/or pathogenic fungi and outcomes of the studies provided better understanding on the upstream regulation of vegetative growth, mating, development, virulence/pathogenicity establishment, and biosynthesis of secondary metabolites in fungi. This review focuses on the characteristics of the basic upstream G protein components and RGS proteins, and their roles controlling various aspects of biological processes in the model filamentous ascomycete fungus Aspergillus nidulans. In particular, their functions in controlling hyphal proliferation, asexual spore formation, sexual fruiting, and the mycotoxin sterigmatocystin production are discussed.

• 미생물학회지
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• 제52권2호
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• pp.226-229
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• 2016

먹물버섯 Coprinellus congregatus의 버섯조직이 자가분해되는 시기에 발현되는 chitinase (Chi2)는 사람에게 질병을 일으키는 Cryptococcus neoformans의 세포벽 두께를 정상 세포벽의 32% 수준까지 감소시킬 뿐만 아니라, 세포 외 섬유상 물질도 제거하였다. Chi2 처리에 의하여 사람에게 알레르기를 유발하는 Alternaria alternata의 생장은 물론 생쥐 모델에서 이 균에 의한 피부알레르기 증상도 감소시켰다.

• Journal of Microbiology
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• 제38권4호
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• pp.230-238
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• 2000

Class III chitin synthases in filamentous fungi are important for hyphal growth and differentiation of several filamentous fungi. A genomic clone containing the full gene encoding Chs4, a class III chitin synthase in Penicillium chrysogenum, was cloned by PCR screening and colony hybridization from the genomic library. Nucleotide sequence analysis and transcript mapping of chs4 revealed an open reading frame (ORF) that consisted of 5 exons and 4 introns and encoded a putative protein of 915 amino acids. Nucleotide sequence analysis of the 5'flanking region of the ORF revealed a potential TATA box and several binding sites for transcription activators. The putative transcription initiation site at -716 position was identified by primer extension and the expression of the chs4 during the vegetative growth was confirmed by Northern blot analysis. Amino acid sequence analysis of the Chs4 revealed at least 5 transmembrane helices and several sites for past-transnational modifications. Comparison of the amino acid sequence of Chs4 with those of other fungi showed a close relationship between P chrysogenum and genus Aspergillus.

• KSBB Journal
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• 제25권1호
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• pp.47-54
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• 2010

The mycelial dispersed growth of Cordyceps sinensis was optimized in submerged batch culture at initial pH of 5.0, 150 rpm, and $25^{\circ}C$. The morphological data showed much more dispersed growth of C. sinenesis at initial pH of 5.0. Also, projected area, main hyphal length and number of tips for the mycelial growth of initial pH 5.0 were higher than those of other initial pHs. The industrial medium for mycelial production of C. sinensis was determined to be molasses of 100 g and crushed brewery yeast of 10 g per liter as carbon and nitrogen sources, respectively. With these culture conditions, the maximum production of mycelia was approximately 30.0 g per liter by batch culture in 5-liter jar fermenter with no controlled pH. This result suggests that large-scale mycelia production of C. sinensis may be possible in submerged batch culture. The hot water extract of mycelia from C. sinensis was mainly composed of 83.0% carbohydrate, 11.8% protein, 1.9% lipid, and 2.4% ash and there were present glucose, mannose, galactose, and arabinose as molar ratio of 8.79 : 2.59 : 1.34 : 1.0 in the carbohydrate, respectively. In the experiment using spleen cell and macrophage, the extract showed potent mitogenic and immuno-stimulating activities and among various components, an important factor that contribute to the immunological activities was turned out to be carbohydrate moiety.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.242-247
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• 2008

In the fungal pathogen Candida albicans, the yeast-to-hyphal transition occurs in response to a broad range of environmental stimuli and is considered to be a major virulence factor. To address whether the zinc homeostasis affects the growth or pathogenicity of C. albicans, we functionally characterized the zinc-finger protein Csr1 during filamentation. The deduced amino acid sequence of Csr1 showed a 49% similarity to the zinc-specific transcription factor, Zap1 of Saccharomyces cerevisiae. Sequential disruptions of CSR1 were carried out in diploid C. albicans. The csr1/csr1 mutant strain showed severe growth defects under zinc-limited growth conditions and the filamentation defect under hypha-inducing media. The colony morphology and the germ-tube formation were significantly affected by the csr1 mutation. The expression of the hyphae-specific gene HWP1 was also impaired in csr1/csr1 cells. The C. albicans homologs of ZRTl and ZRT2, which are zinc-transporter genes in S. cerevisiae, were isolated. High-copy number plasmids of these genes suppressed the filamentation defect of the csr1/csr1 mutant strain. We propose that the filamentation phenotype of C. albicans is closely associated with the zinc homeostasis in the cells and that Csr1 plays a critical role in this regulation.

• 한국토양비료학회지
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• 제44권4호
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• pp.637-649
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• 2011

Soil microorganisms play a major role in improving soil fertility and plant health. Symbiotic arbuscular mycorrhizal fungi (AMF) form a key component of the soil microbial populations. AMF form a mutualistic association with the host plant and exert a positive influence on its growth and nutrient uptake. The establishment of mycorrhizal symbioses with the host plant can positively be influenced by plant growth promoting rhizobacteria through various mechanisms such as increased spore germination and hyphal permeability in plant roots. Though there are evidences that combined interactions between AMF and PGPR can promote the plant growth however mechanisms of these interactions are poorly understood. Better understanding of the interactions between AMF and other microorganisms is necessary for maintaining soil fertility and enhancing crop production. This paper reviews current knowledge concerning the interactions between AMF and PGPR with plants and discusses on enhanced nutrient availability, biocontrol, abiotic stress tolerance and phytoremediation in sustainable agriculture.