• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.413-417
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• 1998

Magnaporthe grisea, the casual agent of rice blast, requires formation of an appressorium, a dome-shaped and well melanized infection structure, to penetrate its host. Environmental cues that induce appressorium formation include hydrophobicity and hardness of contact surface and chemicals from its host. Artificial surfaces are widely used to induce appressorium formation, but frequencies of appressorium induction are not always consistent. To understand variable induction of appressorium formation in M. grisea, several factors were tested on GelBond. High levels of appressorium formation were induced over a wide range of temperature (20~3$0^{\circ}C$) and pH (4~7). spore age up to 3-week-old did not significantly affect appressorium formation, but only a few apressoria on GelBond. However, adenosine specifically inhibited appressorium formation. Adenosine inhibition of appressorium formation was restored by exogenous addition of cAMP. Germ tube tips of M. grisea maintained the ability to differentiate appressoria by chemical inducers on GelBond at least up to 16 h after conidia germination. These results suggest that environmental factors have little effect on the variable induction of appressorium formation on the artificial surface in M. grisea.

• Applied Biological Chemistry
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• v.42 no.3
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• pp.188-192
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• 1999

In order to minimize the mycelial pellet formation, one of the critical obstacles during the fermentation processes of filamentous fungi, an investigation was focused on the culture conditions(media and initial inoculum) and additives(soils, surfactants and polyethylene glycol 200) when a high phosphate-dissolving fungus, Penicillium sp. GL-101, was cultured in liquid media. Culturing the strain in PDB, SDB and YPD media, their pellet sizes decreased to the order of YPD > SDB > PDB. And at the high concentrations of the initial inoculum in the range from $1{\times}10^3\;to\;1{\times}10^6$ conidia/ml, the small sizes of pellet were formed in the PDB media. For the initial inoculum between $1{\times}10^7\;and\;1{\times}10^8$ conidia/ml, however, an amorphous pellet or loose aggregate was formed. The addition of soils, zeolite and diatomite, up to 1.0% decreased the pellet sizes to 3/4 and 1/2, respectively, but the pellet was increased to 2.5 times by the addition of bentonite. Surfactants also affected on the size of pellet; the addition of Triton X-100 and Tween 80 up to 1.0% decreased the pellet sizes maximally to 1/10 and 1/4, respectively, while SDS completely inhibited the fungal growth. Among the four additives tsted, polyethylene glycol 200 was the most effectively reduced the pellet sizes to $0.2{\pm}0.1$mm that resulted in about 25- fold reduction compared to the control.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.259-269
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• 2012

Protein phosphatase 2A (PP2A), a family of serine/threonine protein phosphatases, plays an important role in balancing the phosphorylation status of cellular proteins for regulating diverse biological functions in eukaryotic organisms. Despite intensive studies in mammals, limited information on its role is available in filamentous fungi. Here, we investigated the functional roles of genes for a putative B' delta regulatory subunit (FgPP2AR) and a catalytic subunit (FgPP2AC) of PP2A in a filamentous ascomycete, Fusarium graminearum. Molecular characterization of an insertional mutant of this plant pathogenic fungus allowed us to identify the roles of FgPP2AR. Targeted gene replacement and complementation analyses demonstrated that the deletion of FgPP2AR, which was constitutively expressed in all growth stages, caused drastic changes in hyphal growth, conidia morphology/germination, gene expression for mycotoxin production, sexual development and pathogenicity. In particular, overproduction of aberrant cylindrical-shaped conidia is suggestive of arthroconidial induction in the ${\Delta}FgPP2AR$ strain, which has never been described in F. graminearum. In contrast, the ${\Delta}FgPP2AC$ strain was not significantly different from its wild-type progenitor in conidiation, trichothecene gene expression, and pathogenicity; however, it showed reduced hyphal growth and no perithecial formation. The double-deletion ${\Delta}FgPP2AR;{\Delta}FgPP2AC$ strain had more severe defects than single-deletion strains in all examined phenotypes. Taken together, our results indicate that both the putative regulatory and catalytic subunits of PP2A are involved in various cellular processes for fungal development in F. graminearum.

• The Korean Journal of Mycology
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• v.33 no.2
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• pp.89-91
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• 2005

In April of 2003 to 2004, the gray mold disease caused by Botrytis cinerea on Hypericum ascyron was occurred in the exhibition field of Gyeongsangnam-do Agricultural Research and Extension Services, at Hamyang-gun in Korea. The disease symptoms were started with water-soaking lesions in stem and the infected plants became withered, discolored and died. The conidia and mycelia of the pathogen appeared on stems of infected plants. The conidia were 1-celled and mostly ellipsoid or ovoid in shape and their color was light gray. The size of conidia was $4{\sim}16\;{\times}\;3{\sim}8\;{\mu}m$ and that of conidiophores was $12{\sim}26\;{\mu}m$ respectively. The pathogen formed sclerotia abundantly on potato-dextrose agar. The optimum temperature for sclerotial formation was $20^{\circ}C$. Pathogenicity of the causal organism was proved according to Koch's postulate. The causal organism was identified as Botrytis cinerea based on mycological characteristics. This is the first report on gray mold of H. ascyron caused by B. cinerea in Korea.

• Research in Plant Disease
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• v.13 no.3
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• pp.216-219
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• 2007

Gray mold caused by Botrytis cinerea occurred on Prunus mume Sieb. & Zucc. in an experimetal orchard of Gyeongsangnam-do Agricultural Research and Extension Services in Korea from 2005 to 2007. The symptoms usually started with water-soaking lesions and hollow depression on the fruit surface. The conidia of the pathogen appeared on the surface fruits. The conidia were one celled and mostly ellipsoid or ovoid in shape and were colorless or pale brown in color. The conidia were $6{\sim}17{\times}4{\sim}10{\mu}m$ in size and conidiophores were $15{\sim}30{\mu}m$ in length. The sclerotial formed abundantly on potato-dextrose agar, They were flat or irregular in shape and black in color The optimum temperature for sclerotial formation was $20^{\circ}C$. On the basis of mycological characteristics and pathogenicity test on host plants, the fungus was identified as Botrytis cinerea Persoon: Fries. This is the first report on gray mold of P. mume caused by B. cinerea by in Korea.

• The Plant Pathology Journal
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• v.19 no.2
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• pp.92-96
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• 2003

The study was conducted to determine the cultural conditions and the effect of inert fillers for melanization and sporulation abilities of sodium alginate pellets, and the weeding efficacy of the formula in the field. Melanin production of E. nematosporus was affected by striking frequency. Percentage of melanized beads was increased to 80.6% at higher rpm up to 180. The melanized pellets produced more conidia with abundant mucilage than unmelanized pellets. Shaker culture of Epicoccosorus nematosporus with sodium alginate yielded a total of 55 mg per 100 pellets. Percentage of melanized pellets was highest with 81.0% and 83.3% of melanization, when wheat bran and rice polish were amended and produced the conidia with 65.4 and 68.4 mg per 100 pellets, respectively. When 1 L of conidial suspension of 6.0$\times$$10^5$ conidia per ml was applied on 30-day-old plants in a plot, 74.5% of the plants were killed within 20 days, whereas, its melanized sodium alginate pellets killed 57.8% of the plants in the same period. The number of tuber formation of Eleocharis kuroguwai in the untreated control plots was 128.5 per plot, but those of the plots treated with conidial suspension and melanized pellets were 22.1 and 39.7, respectively, at the end of the season. Results of this study showed that melanization of mycelia-mixed sodium alginate are an important sporulation factor in E. namatosporus as a mycoherbicide.

• Research in Plant Disease
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• v.12 no.1
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• pp.58-61
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• 2006

Ggray mold caused by Botrytis cinerea occurred on Balsam pear (Momordica charantia) at Daesan-myon, Changwon city, Gyeongnam province in Korea from 2004 to 2006. The disease symptoms usually started with water-soaking lesions on the fruits tip and stem, and then the infected plants became withered and eventually died. The conidia of the pathogen appeared on the surface of fruit and stem of infected plants. The conidia were one celled and mostly ellipsoid or ovoid in shape and were light gray in color, The conidia were $6{\sim}20X4{\sim}12{\mu}m$ in size and conidiophores were $14{\sim}30{\mu}m$ in length. The sclerotia formed abundantly on potato-dextrose agar 18 days after incubation. The optimum temperature for sclerotial formation was $20^{\circ}C$. Pathogenicity of the causal organism was proved according to Koch,s postulates. The causal organism was identified as Botrytis cinerea Persoon: Fries based on the mycological characteristics. This is the first report on gray mold of M. charantia caused by B. cinerea in Korea.

• The Korean Journal of Mycology
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• v.34 no.2
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• pp.122-124
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• 2006

In March of 2005, gray mold disease caused by Botrytis cinereu on Stachys sieboldii Miq. was occurred in the mud cellar storage of Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The symptoms started with water-soaked and rotten in the tubers. The conidia were one celled and mostly ellipsoid or ovoid in shape and light gray in color. The conidia were $5{\sim}16{\times}4{\sim}12{\mu}m$ in size and the conidiophores were $14{\sim}30{\mu}m$ in length. The pathogen formed conidia and sclerotia abundantly on PDA. The optimal temperature for mycelial growth and sclelotia formation was $20^{\circ}C$. On the basis of symptom, mycological characteristics and pathogenicity test on host plants, the fungus was identified as Botrytis cinerea Persoon: Fries. This is the first report on gray mold of S. sieboldii caused by B. cinerea in Korea.

• Research in Plant Disease
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• v.26 no.1
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• pp.38-43
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• 2020

The genome of the rice blast fungus Magnaporthe oryzae contains several types of transposable elements (TEs), and some TEs cause genetic variation that allows M. oryzae to evade host detection. We studied how five abundant TEs in rice pathogens, Pot3, Pot2, MAGGY, Line-like element (MGL) and Mg-SINE, are expressed under diverse conditions related to growth, development, and stress. Expression of Pot3 and Pot2 was activated in germinated conidia and mycelia treated with tricyclazole. Retrotransposon MAGGY was highly expressed in appressoria and tricyclazole-treated mycelia. MAGGY and Pot2 were also activated during the early and late stages of perithecia development. MGL was up-regulated in conidia and during conidial germination but not during appressorium formation. No noticeable expression of Mg-SINE was observed under most conditions. Our results should help investigate if and how condition-specific expressions of some TEs contribute to the biology and evolution of M. oryzae.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.156-161
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• 2000

A wilt disease occurred on greenhouse-grown eggplants at Yeojoo, Korea in 1997. The wilted eggplants had leaves with gradual yellowing, interveinal necrosis, and marginal crinkling. Vascular tissues of diseased stems were discolored, turned black, and microsclerotia developed at the base of stems. The disease progressed from lower parts of the plants upward. Fungal isolates from discolored vascular tissues were initially whitish to cream color on potato-dextrose agar (PDA) plate, which later turned black due to the formation of microsclerotia. Conidiophores were erect, hyaline, verticillately branched, and had 3 or 4 phialides arising at each node. Phialides were hyaline, arranged in whorls, and measured as 17.5-32.5 x 2-3$\mu\textrm{m}$. Conidia were hyaline, ellipsoidal to sub-cylindrical, mainly one-celled, and measured as 5-8.8 x 2-4$\mu\textrm{m}$. Conidia were borne in small clusters at the tips of phialides. Microsclerotia formed on PDA plates, and consisted of globular cells that formed irregular masses of various shapes. Chlamydospores were absent. Based on these cultural and morphological characteristics, the fungus was identified as Verticillium dahliae Klebahn. Pathogenicity tests by root cutting, root dipping or soil drenching resulted in similar symptoms observed in the naturally infected eggplants. This is the first report on occurrence of Verticillium wilt of eggplant in Korea.