• Research in Plant Disease
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• v.26 no.3
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• pp.159-169
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• 2020

Pectobacterium carotovorum subsp. carotovorum (Pcc) causes bacterial soft rot on a wide range of crops worldwide, especially in countries with warm and humid climates. This study was conducted to establish an efficient screening method for resistant cultivars of Chinese cabbage to bacterial soft rot. Resistance degrees of 65 commercial Chinese cabbage cultivars to the Pcc KACC 10225 isolate were investigated. For further study, three Chinse cabbage cultivars (Taebong, Hadaejangkun, CR Alchan) showing different level of resistance to the bacterium were selected. The development of bacterial soft rot on the cultivars was tested according to several conditions such as growth stage of Chinse cabbage seedling, inoculum concentration, and incubation temperature after inoculation. On the basis of the results, we suggest that an efficient screening method for resistant Chinses cabbage to Pcc is to inoculate twenty one-day-old seedlings with a bacterial suspension of Pcc at a concentration of 1×10⁷ cfu/ml, and to incubate the plants in a dew chamber at 25℃ for 24 hr and then to cultivate in a growth room at 25℃ and 80% relative humidity with 12-hr light per day.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.25-27
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• 2003

Since 1993, a total of 50 problematic plant diseases unrecorded in Korea were surveyed in Gyeongnam province. Totally 34 new host plants to corresponding pathogens investigated in this study were 5 fruit trees, 9 vegetables, 12 ornamental plants, 3 industrial crops, and 5 medicinal plants. Among the newly recorded fruit tree diseases, fruit rot of pomegranate caused by Coniella granati and Rhizopus soft rot of peach caused by Rhizopus nigricans damaged severely showing 65.5% and 82.4% infection rate. Among the vegetable diseases, corynespora leaf spot of pepper caused by Corynespora cassiicola and the crown gall of pepper caused by Agrobacterium tumefaciens, powdery mildew of tomato caused by Oidiopsis taurica were the most severe revealing 47.6%, 84.7%, and 54.5% infection rate in heavily infected fields, respectively. In ornamental plants, collar rot of lily caused by Sclerotium rolfsii, gray mold of primula caused by Botrytis cinerea, soot leaf blight of dendrobium caused by Pseudocercospora dendrobium, sclerotinia rot of obedient plant caused by Sclerotinia sclerotiorum showed 32.7 to 64.8% disease incidence. On three industrial plants such as sword bean, broad bean, and cowpea, eight diseases were firstly found in this study. Among the diseases occurring on broad bean, rust caused by Uromyces viciae-fabae and red spot caused by Botrytis fabae were the major limiting factor for the cultivation of the plant showing over 64% infection rate in fields. In medicinal plants, anthracnose of safflower caused by Collectotrichum acutatum was considered the most severe disease on the plant and followed by collar rot caused by Sclerotium rolfsii.(중략)

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.70-78
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• 2021

Identifying the extracellular metabolites of microorganisms in fresh vegetables is industrially useful for assessing the quality of processed foods. Pectobacterium carotovorum subsp. carotovorum (PCC) is a plant pathogenic bacterium that causes soft rot disease in cabbages. This microbial species in plant tissues can emit specific volatile molecules with odors that are characteristic of the host cell tissues and PCC species. In this study, we used headspace solid-phase microextraction followed by gas chromatography coupled with mass spectrometry (HS-SPME-GC-MS) to identify volatile compounds (VCs) in PCC-inoculated cabbage at different storage temperatures. HS-SPME-GC-MS allowed for recognition of extracellular metabolites in PCC-infected cabbages by identifying specific volatile metabolic markers. We identified 4-ethyl-5-methylthiazole and 3-butenyl isothiocyanate as markers of fresh cabbages, whereas 2,3-butanediol and ethyl acetate were identified as markers of soft rot in PCC-infected cabbages. These analytical results demonstrate a suitable approach for establishing non-destructive plant pathogen-diagnosis techniques as alternatives to standard methods, within the framework of developing rapid and efficient analytical techniques for monitoring plant-borne bacterial pathogens. Moreover, our techniques could have promising applications in managing the freshness and quality control of cabbages.

• Research in Plant Disease
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• v.29 no.3
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• pp.304-309
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• 2023

Wilted and water-soaked lesion symptoms were observed on cucumbers in greenhouses located in Daejeon, Chungcheongnam-do, Korea, in June 2021. A bacterial strain, designated KNUB-04-21, was isolated from the cucumbers, which was subsequently identified as Pectobacterium brasiliense through a phylogenetic analysis based on sequences of the 16S rRNA region, dnaX, leuS, and recA genes. The biochemical characteristics of KNUB-04-21 were also similar to those of P. brasiliense through investigation using the API ID 32 GN system. The pathogenicity of KNUB-04-21 was confirmed by inoculating it into healthy cucumber plants. The reisolated strains were also found to be same to the original strain. To our knowledge, this is the first report of P. brasiliense being identified as the causative agent of cucumber soft rot in Korea.

• Research in Plant Disease
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• v.30 no.1
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• pp.95-98
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• 2024

In a survey conducted in March 2023, Euphorbia hypogaea plants cultivated within greenhouses in Yongin, Korea exhibited water-soaked areas near the stem base, close to the soil. Subsequent isolation from diseased E. hypogaea led to the identification of a bacterial strain, designated as CBNUMPBL-103. The isolate was identified as Dickeya dadantii through sequencing of the 16s rRNA and phylogenetic analysis. The pathogenicity of the isolate was confirmed by inoculating it into healthy E. hypogaea, resulting in the manifestation of similar symptoms observed during the survey. The re-isolated strain recovered from inoculated plants showed a similar morphology with the inoculated strain. This is the first documentation of D. dadantii causing soft rot of E. hypogaea in Korea.

• The Plant Pathology Journal
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• v.40 no.5
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• pp.537-550
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• 2024

Pectobacterium is a major bacterial causal agent leading to soft rot disease in host plants. With the Arabidopsis-Pectobacterium pathosystem, we investigated the function of an Arabidopsis thaliana WRKY55 during defense responses to Pectobacterium carotovorum ssp. carotovorum (Pcc). Pcc-infection specifically induced WRKY55 gene expression. The overexpression of WRKY55 was resistant to the Pcc infection, while wrky55 knockout plants compromised the defense responses against Pcc. WRKY55 expression was mediated via Arabidopsis COI1-dependent signaling pathway showing that WRKY55 can contribute to the gene expression of jasmonic acid-mediated defense marker genes such as PDF1.2 and LOX2. WRKY55 physically interacts with Arabidopsis ORA59 facilitating the expression of PDF1.2. Our results suggest that WRKY55 can function as a positive regulator for resistance against Pcc in Arabidopsis.

• The Korean Journal of Mycology
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• v.30 no.2
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• pp.166-169
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• 2002

A fruits soft rot caused by Rhizopus stolonifer found on citrus fruit in Jinjn City Agricultural Products Wholesale Market. The disease infection usually started from wounding. At first, the lesions started water soaked and rapidly softened and diseased lesion gradually expanded to other fruits in the same container. The mycelia grew vigorously on the surface of fruits and formed sporangia, sporangiophores and stolons. Sporangiophores were $900{\sim}4300{\mu}m$ in size. Sporangia were globose or subglobose and $98{\times}346{\mu}m$ in size. The color of sporangia was white at first and then turned black with many spores. Columella were globose or ellipsoid and $60{\sim}216{\times}72{\sim}143{\mu}m$ in size. Sporangiospores were globose or ellipsoid, brownish-black streaked and $8{\sim}18.3{\mu}m$ in diameter. Zygospores were globose, black and $98{\sim}176{\mu}m$ in size. The optimum temperature for mycelial growth of the fungus on PDA was $25^{\circ}C$. The causal fungus was identified as Rhizopus stolonifer. This is the first report of rhizopus soft rot on citrus fruit caused by R. stolonifer in Korea.

• Research in Plant Disease
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• v.14 no.2
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• pp.127-130
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• 2008

Rhizopus soft rot caused by Rhizopus stolonifer on June, 2008 occurred on Rubus crataegifolius Bunge in the box at Jinju City Wholesale Market of Agricultural Products at Gyeongnam province in Korea. The infected fruits were rapidly water-soaked, softened, black and eventually rotted. The symptoms occurred after infecting wounds at harvest time. The colony were white to light brown, formed much sporangiospores. The optimum temperature of the fungus on potato dextrose agar was $30^{\circ}C$. Sporangiophores were $12{\sim}25{\mu}m$ in width. Sporangia were globose or hemispheric, white at first and gradually to black, and $82{\sim}195{\mu}m$ in size. Columella were hemispheric, and $70{\sim}92{\mu}m$ in size. Sporangiospores were irregular round or oval, brownishblack and $9{\sim}21{\times}7{\sim}8{\mu}m$ in size. On the basis of symptom, mycological characteristics and pathogenicity of the fungus, the causal fungus was identified as Rhizopus stolonifer. This is the first report of Rhizopus soft rot by R. stolonifer on R. crataegifolius in Korea.

• Mycobiology
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• v.29 no.3
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• pp.176-178
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• 2001

A soft rot of fruits caused by Rhizopus stolonifer occurred on cherry tomato in Jinju City Agricultural Products Wholesale Market, Korea. The disease infection usually started from wounding after cracking of fruits. At first, the lesions started with water soaked and were rapidly softened and diseased lesion gradually expanded. The mycelia grew vigorously on the surface of fruits and formed stolons. Colonies on potato dextrose agar at $25^{\circ}C$ were white cottony at first, becoming heavily speckled by the presence of sporangia and the browinish black, and spreading rapidly by means of stolons fired at various points to the substrate by rhizoids. Sporangia were $82.7{\times}196.7{\mu}m$ in size and globose or sub-globose with somewhat flattened base. The color of sporangia was white at first and then turned black with many spores, and never overhanging. Sporangiophores were $2.6{\sim}5.8{\times}12.3{\sim}24.2{\mu}m$ in width, smooth-walled, non-septate, tight brown, simple, long, arising in groups of $3{\sim}5$ from stolons opposite rhizoids. Sporangiospores were $8.2{\sim}18.8{\mu}m$ long, irregular, round, oval, elongate, angular, and browinish-black streaked. Columella was $64.1{\times}136.3{\mu}m$. brownish gray, and umberella-shaped when dehisced. The causal organism was identified to be R. stolonifer. This is the first report of Rhizopus soft rot on cherry tomato caused by R. stolonifer in Korea.

• Journal of Plant Biotechnology
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• v.39 no.4
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• pp.295-299
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• 2012

We performed in vitro assay and field trials to assess levels of changes in intrinsic properties and resistance against soft rot of the potato cv. Dejima upon the introduction of a soybean calmodulin 4 gene (SCaM4). Field trials with four lines overexpressing SCaM4 gene were conducted over two seasons, and harvested tubers were evaluated in bioassay for resistance to Pectobacterium carotovorum ssp. carotovorum. The SCaM4 transgenic potato lines inoculated with $10^8$ CFU/ml of P. carotovorum ssp. carotovorum showed enhanced resistance compared to control. Among the SCaM4 transgenic lines, the transgenic line SCaM4-4 exhibited the highest tolerance to soft rot in vitro assays, so did in field trials. In the field trial, the soft rot resistance of SCaM4-4 line was more than 5 times higher compared to that of control cultivar, Dejima. The major agronomic characteristics of the SCaM4 transgenic lines were not different from those of the nontransgenic 'Dejima'. The result demonstrated that the transformation of a calmodulin 4 gene was a successful strategy in development of potato cultivar enhanced to soft rot.