• The Plant Pathology Journal
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• v.30 no.3
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• pp.288-298
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• 2014

We examined the efficacy of a bacterium for biocontrol of the root-knot nematode (RKN) Meloidogyne hapla in carrot (Daucus carota subsp. sativus) and tomato (Solanum lycopersicum). Among 542 bacterial isolates from various soils and plants, the highest nematode mortality was observed for treatments with isolate C1-7, which was identified as Bacillus cereus based on cultural and morphological characteristics, the Biolog program, and 16S rRNA sequencing analyses. The population density and the nematicidal activity of B. cereus C1-7 remained high until the end of culture in brain heart infusion broth, suggesting that it may have sustainable biocontrol potential. In pot experiments, the biocontrol efficacy of B. cereus C1-7 was high, showing complete inhibition of root gall or egg mass formation by RKN in carrot and tomato plants, and subsequently reducing RKN damage and suppressing nematode population growth, respectively. Light microscopy of RKN-infected carrot root tissues treated with C1-7 showed reduced formation of gall cells and fully developed giant cells, while extensive gall cells and fully mature giant cells with prominent cell wall ingrowths formed in the untreated control plants infected with RKNs. These histopathological characteristics may be the result of residual or systemic biocontrol activity of the bacterium, which may coincide with the biocontrol efficacies of nematodes in pots. These results suggest that B. cereus C1-7 can be used as a biocontrol agent for M. hapla.

• Research in Plant Disease
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• v.14 no.1
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• pp.64-67
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• 2008

In 2005 and 2007, petiole and root rot of Spathiphyllum spp. was occurred at commercial greenhouse during summer (June-September) in Koyang city and Yongin city, Kyunggi-do, Korea. The pathogenic fungus was isolated from diseased plants and the cultural and morphological chracteristic were observed. Conidia were rod in shape, 1-3 septa and $67.5-95.0{\times}4.8-6.5\;{\mu}m$ (av. $82.0{\times}6.0\;{\mu}m$) in size. The optimum temperature for the mycelial growth of the isolates was $27^{\circ}C$. According to result the pathogenicity test, first disease symptoms appeared five days after inoculation. On the basis of mycological characteristics and pathogenicity test on host plants, the fungus was identified as Cylindrocladium spathiphylli. This is the first report on Spathiphyllum spp. caused by C spathiphylli in Korea.

• The Korean Journal of Mycology
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• v.40 no.1
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• pp.44-48
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• 2012

Ginseng (Panax ginseng) is one of the most widely cultivated medicinal herb in Korea. However, yield losses reached up to 30~60 % due to various diseases during 3 or 5 years of ginseng cultivation. Therefore, successful production of ginseng roots depends primarily on the control of diseases. The objective of this study is to select potential multifunctional biocontrol agents from actinomycetes for the control of multiple ginseng diseases as an alternative to fungicides. Ninety three Streptomyces strains were selected and their ability to produce antibiotics, siderophore and lytic enzymes such as protease and cellulose were investigated. Eight of the isolates, strains A75, A501, 515, 523, A704, A1444, A3265 and A3283 produced cellulase and protease. These strains also produced siderophore and showed potent antifungal activity against Botrytis cinerea, Cylindrocarpon destructans, Collectotricum gloeosporioides, Phytophthora capsici and Rhizoctonia solani causing ginseng root rot.

• Research in Plant Disease
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• v.26 no.4
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• pp.256-263
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• 2020

Incidence of Fusarium wilt was surveyed in fields of summer radish in Gangwon province in Korea in 2018 and 2019. The disease started in early July and spread rapidly in hot summer of late July and August and in severe case, reached up to 80% in a field in Gangneung area. Symptoms in the seedling stage include poor growth and browning of internal tissue of root. During mid-growth, the leaves of diseased plant turned yellow over time, the surface of the roots changed from white to blackish, and the vascular tissues turned brown. A total of 23 isolates was obtained from the diseased plants and identified as Fusarium oxysporum f. sp. raphani by elongation factor-1α and intergenic spacer sequence analysis. Pathogenicity of the isolates was tested by artificial inoculation to the radish and other plants. All the isolates tested were pathogenic to radish plant, although there were differences in virulence on radish 11 cultivars. However, the isolates were not virulent to other plants except some cruciferous vegetables including Brussels sprouts, rocket, stock, and turnip. The results of pathogenicity test showed that it is necessary to rotate with crops other than cruciferous vegetables in order to prevent Fusarium wilt from radish fields.

• The Plant Pathology Journal
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• v.17 no.5
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• pp.290-294
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• 2001

Forty(40) isolates of Fusarium oxysporum isolated from wilting tomato plants at Buyeo of Korea in 1997 were inoculated to four tomato cultivars (Ponderosa, Okitsu 3, Walter, and Zuiken) to examine pathogenic reactions. Isolation rates of F. oxysporum f. sp. lycopersici (FOL) races 1 and 2, and F. oxysporum f. sp. radicis-lycopersici(FORL) were 3.5%, 24.5%, and 57.5%, respectively. Mycelial growth on potato-dextrose agar at different temperature for the three pathogens was $26^{\circ}$. In the pathogenicity tests, however, the range of optimum temperature for disease development for FORL was between 15 and $20^{\circ}$, while that for races 1 and 2 of FOL were specifically pathogenic to tomato only. This suggests that host ranges of FORL and FOL differ significantly.

• Journal of Microbiology
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• v.40 no.1
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• pp.55-62
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• 2002

Biodiversity af yeasts in various natural environments including soils, swamps and plants was investigated. By molecular identification methods based on the partial sequences of 265 rDNA, 69 isolates were assigned to 44 taxa including 27 known species. The remaining 17 taxa could potentially form new species. All of them were classified into Ascomycota, Hymenomycetes, Urediniomycetes and Ustilaginomycetes. Ascomycetous and ustilaginomycetous yeasts were generally isolated from flower samples, and hymenomycetous and urediniomycetous yeasts were generally isolated from soil samples. Distribution of yeast groups exhibited geographical variation. Yeast biodiversity of root sail also varied according to the associated plant species.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.348-353
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• 1994

The activity fractionation upon the MeOH extract of the root of trichosanthes kirilowii led to the isolation of eight cucurbitane tritepense namely cucurbitacin .betha. (I), isocucurbitacin .betha.(II), cucurbitacin D(III), isocucurbitacin D(IV), 3-epi-isocucurbitacin .betha(V), dihydrocucurbitain .betha. (VI), dihydroisocucurgbitachin .betha. (VII) and dihydrocucurbitacin E (VIII), as active principles. All isolates were shown to exhibit significant cytotoxicity against cultured human tumor cells, including A-549, Sk-OV-3, Sk-MEL-2, XF-498 and HCT 15, with an exceptionally high potency.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.236-238
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• 1987

A bacterial disease of elephant foot, Hydrosome rivieri Engl., was newly found in Taejon, Korea in August 1986. The affected plants showed symptoms of soft rot on leaf blades and petioles. Bacterial isolates from affected plants found to be pathogenic to elephant foots by antificial inoculation, producing similar symptoms with those produced naturally. The baterium was also pathogenic to carrot, Chinese cabbage, radish, potato and onion, and developed symptom of soft root on them. On the basis of bacteriological characteristics and pathogenicity, tested bacterium was identified as Erwinia carotovora subsp. carotovora and this disease was proposed to name 'Bacterial soft rot of elephant foot'.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.138-141
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• 2002

A promising biocontrol agent, A2l-4, against Phytophthora blight of pepper was selected from 351 bacterial isolates collected from rhizosphere soils and roots of onion (Allium fistulosum L.). The isolate A21-4 was identified as Serratia plymuthica based on its 16S rRNA sequence and key characteristics as compared with that of an authentic culture of S. plymuthica (ATCC No. 6109D01). The isolate readily colonized on roots of various crops including pepper when inoculated on seed and not. Strain A2l-4 showed narrow spectrum of antibiotic activity, as revealed in its strong inhibitory activity to the genera Pythium and Phytophthora, but not to Fuasrium and Rhizoctonia. In pot experiments, none of the pepper seedlings treated with A2l-4 were infected by Phytophthora capsici, while 86% of the control plants were killed by the pathogen.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.140-143
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• 1994

Comparison of susceptibility of asparagus (Asparagus officinalis L.) seedlings and plantlets to different fusarial species was made to determine whether in vitro propagated asparagus plantlets can be used as a substitute for seedlings in histopathological study on the infection processes of Fusarium species to asparagus. Fusarium oxysporum was isolated most frequently (50% of the total) from lesions of root and crown rot of asparagus cultivated in the field followed by F. moniliforme (8.8% of the total) and F. solani (2.9% of the total). Plantlets and seedlings of all asparagus were susceptible to f. moniliforme and F. oxysporum isolates, but those were not susceptible to both avirulent F. oxysporum (AVFO) and F. solani in pathogenicity tests. Overall, there were no differences between seedlings and plantlets in the susceptibility to virulent fusarial infections. In vitro propagated asparagus plantlets, therefore, could be used as a substitute for seedlings in histopathological study on the infection processes of Fuasrium species to asparagus.