• Research in Plant Disease
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• v.29 no.4
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• pp.345-362
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• 2023

Anthracnose, caused by the Colletotrichum genus, comprises a significant number of plant pathogens and poses a major threat to fruit production worldwide, including South Korea. Colletotrichum species were identified associated with anthracnose in fruits such as apple, persimmon, plum, peach, jujube, walnut, and grape. A polyphasic approach, including morphology, multigene phylogenetics, and pathogenicity testing, was used. Additionally, the in-vitro sensitivity of identified Colletotrichum species to common fungicides was also evaluated. A total of nine Colletotrichum species within two complexes, namely gloeosporioides and acutatum, have been identified as the causal agents of anthracnose in common fruits in South Korea. In the gloeosporioides complex, we found Colletotrichumaenigma, C. fructicola, C. gloeosporioides, C. horii, C. siamense, and C. viniferum. Meanwhile, in the acutatum complex, C. fioriniae, C. nymphaeae, and C. orientalis were identified. Notably, C. fructicola, C. siamense, C. fioriniae, and C. nymphaeae were reported for the first time from apple, C. siamense, C. fioriniae and C. nymphaeae from plum, C. siamense, C. fructicola, and C. fioriniae frompeach, C. siamense and C. horii from persimmon, C. fioriniae from Omija (Schisandra), C. orientalis from walnut, C. nymphaeae from jujube, and C. aenigma, C. fructicola, and C. siamense fromgrape. Fungicide sensitivity tests revealed significant variation in the EC₅₀ values among specific Colletotrichum species when exposed to different fungicides. Moreover, the same Colletotrichum species isolated from different host plants displayed varying sensitivity to the same fungicide.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.282-289
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• 2012

The root rot of pepper (Capsicum annuum L.) caused by Phytophthora capsici is one of the most important diseases affecting this crop worldwide. This work presents the evaluation of the capacity of Streptomyces griseus H7602 to protect pepper plants against Phytophthora capsici and establishes its role as a biocontrol agent. In this study, we isolated an actinomycete strain H7602 from rhizosphere soil, identified it as Streptomyces griseus by 16S rRNA analysis and demonstrated its antifungal activity against various plant pathogens including P. capsici. H7602 produced lytic emzymes such as chitinase, ${\beta}$-1,3-glucanase, lipase and protease. In addition, crude extract from H7602 also exhibited destructive activity toward P. capsici hyphae. In the pot trial, results showed the protective effect of H7602 against pepper from P. capsici. Application of H7602 culture suspension reduced 47.35% of root mortality and enhanced growth of pepper plants for 56.37% in fresh root and 17.56% g in fresh shoot as compared to control, resulting in greater protection to pepper plants against P. capsici infestation. Additionally, the enzymatic activities, chitinase and ${\beta}$-1,3-glucanase, were higher in rhizosphere soil and roots of pepper plants treated with H7602 than other treated plants. Therefore, our results indicated a clear potential of S. griseus H7602 to be used for biocontrol of root rot disease caused by P. capsici in pepper.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.189-196
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• 2016

Several microorganisms in particular Bacillus subtilis group have been isolated from diverse places such as soils and the gastrointestinal tract of ruminants etc., and used as biocontrol agent against various plant pathogens and utilized as plant growth promoting agents. Among them, Bacillus is well known as one of the most useful bacteria for biocontrol and plant growth promotion. Bacterium GH1-13 was isolated from a reclaimed paddy field in Wando Island and identified as Bacillus velezensis using phylogenetic analysis on the basis of 16S rRNA and gyrB gene. It was confirmed that GH1-13 produced indole acetic acid (IAA) associated with promoted growth of rice root. GH1-13 showed characteristics of antagonization against the main pathogen of rice as well as diverse pathogenic fungi. GH1-13 had biosynthetic genes, bacillomycin, bacilycin, fengycin, iturin, and surfactin which are considered to be associated closely with inhibition of growth of pathogenic fungi and bacteria. This study showed that GH1-13 could be used as a multifunctional agent for biocontrol and growth promotion of crop.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.56-65
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• 2006

An antagonistic bacterial isolate, that inhibits the growth of plant pathogens, was selected and identified from 5,000 isolates screened from the rhizosphere of various crop plants. An isolate Bacillus sp. N32, tested against Colletotrichum gloeosporioides causing anthracnose disease in hot pepper, produced both a heat resistant antifungal protein and a heat sensitive antifungal protein. The heat resistant protein was partially purified by Ammonium sulfate fractionation and gel filtration chromatography. The bioautography showed that the proteins possessed high antifungal activity. The biosynthetic gene cluster responsible for the heat resistant antifungal protein was cloned from cosmid library using DNA probe obtained from PCR product with the primers targeting the conserved nucleotide sequence of the synthetic genes reported earlier, Most of the clones obtained showed higher homology to fengycin antibiotic synthetic gene family reported earlier. On the other hand, the heat sensitive protein was isolated from SDS-PAGE and electroblotting to determine the N-terminal amino acid sequences. The heat sensitive antifungal protein gene was cloned from the ${\lambda}-ZAP$ libraries using a DNA probe based on the N-terminal amino acid sequences of the heat sensitive protein. We are contemplating to clone and sequence the whole gene cluster encoding the heat sensitive protein for further analysis.

• Research in Plant Disease
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• v.12 no.3
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• pp.153-157
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• 2006

In 2005, average temperature was lower, and average rainfall was less than those of previous year. The diseases of rice, barley, pepper, chinese melon, apple and oriental pear were surveyed. Bacterial blight, bacterial grain rot, and panicle disease of rice, black rot of pear, and white rot and bitter rot of apple were severe. Especially, brown rot of rice occurred four times higher than those of previous year. Panicle blight of rice increased about 3 times, compared with the previous year, presumed that the higher rainy days, rainfall and RH promoted spread of the fungal pathogens to panicles of rice. The diseases of rice leaf blast, sudden wilt syndrome, downy mildew and powdery mildew of chinese melon in plastic greenhouse, and virus diseases of hot pepper occurred distinctly less than those of the previous year. Another diseases surveyed occurred similar or less.

• Journal of Life Science
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• v.22 no.9
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• pp.1137-1144
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• 2012

Inflammation is a host defense mechanism that is activated in response to harmful substances or pathogens. However, an excessive inflammatory response is a problem in itself. Macrophages secrete inflammatory mediators such as nitric oxide (NO) or cytokines through various pathways such as the nuclear factor kappa B (NF-${\kappa}B$)-activated pathway after recognizing pathogen-like lipopolysaccharides (LPSs). In this study, anti-inflammatory effects of Eupatorium chinensis var. simplicifolium (EUC) extracts were investigated using LPS-stimulated RAW 264.7 macrophages. The EUC root extract significantly reduced NO production, inducible nitric oxide synthase (iNOS) expression, and cyclooxygenase-2 expression in a concentration-dependent manner. In addition, the EUC root extract reduced phosphorylation of mitogen-activated protein kinases and protein kinase B, which is upstream of NF-${\kappa}B$. The EUC root extract also reduced the degradation of inhibitory kappa B. These results indicate that EUC root extract exerts anti-inflammatory effects, which are mediated by inhibition of iNOS expression and the NF-${\kappa}B$ pathway.

• The Korean Journal of Mycology
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• v.46 no.4
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• pp.479-490
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• 2018

Red pepper is seriously damaged by thrips (Thrips palmi) and anthracnose caused by Colletotrichum acutatum throughout its development. Because of biotic constraints, producers often depend on chemicals that are expensive and have adverse effects on the environment, operator, and beneficial insects. In addition, resistance is developed because of the repeated use of chemicals. In recent decades, the use of microorganisms in crop protection has become a credible alternative because it is eco-friendly. In this study, we aimed to select isolates with insecticidal and fungicidal activities against the pathogens that cause anthracnose and thrips. We treated T. palmi adults and juveniles with 13 strains of entomopathogenic fungi (isolated from the soil by using the insect-bait method), and 6 strains showed excellent insecticidal activity (70-100%) 5 days after the treatment. The selected isolates were cultured with C. acutatum to screen for the strain with excellent anti-fungal activities, among which an isolate FT333 showed more than 95% control efficacy against C. acutatum in vitro. The isolate was identified as Isaria javanica through its morphological characteristics and phylogenetic analysis of the ITS and ${\beta}-tubulin$ nucleotide sequences. The Isaria javanica FT333 isolate could be used effectively for dual bio-control of thrips and anthracnose during red pepper cultivation.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.390-400
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• 2019

In this study, strains isolated from soil samples collected from Busan, Changwon, and Jeju Island were examined to verify their abilities of phosphate solubilization and nitrogen fixation, production of indole-3-acetic acid (IAA), siderophore, and 1-aminocylopropane-1-carboxylyic acid (ACC) deaminase in order to select strains that promote plant growth and play a role in biocontrol of pests or pathogens. According to the results of this study, most of the isolated strains were found to have ability of phosphate solubilization, nitrogen fixation, IAA production, siderophore production, and production of ACC deaminase. These isolated strains might help plant growth by directly improving absorption of nutrients essential for phosphate solubilization and nitrogen fixation. In addition, they can promote plant growth and control resistance to plant diseases through extracellular enzyme activity and antifungal activity. In addition, most of the selected strains were found to survive in various environmental conditions such as temperature, salinity, and pH. Therefore, Pseudomonas plecoglossicida ANG14, Pseudarthrobacter equi ANG28, Beijerinckia fluminensis ANG34, and Acinetobacter calcoaceticus ANG35 were finally selected through a comparative advantage analysis to suggest their potential as novel biological agents. Further studies are necessary in order to prove their efficacy as novel biological agents through formulation and optimization of effective microorganisms, their preservation period, and crop cultivation tests.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.302-310
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• 2023

In this study, the extent of the impact of rainfall on the outbreak of fire blight during the blossom infection risk period was explored. In the Chungnam province, the outbreak of fire blight disease began in 2015, and changes in the outbreak's scale were most pronounced between 2020 and 2022, significantly escalating from 63 orchards in 2020 to 170 orchards in 2021, before decreasing to 46 orchards in 2022. In 2022, the number of incidence has decreased and the number of canker symptom in branches has also decreased. It was evaluated that the significant decrease of fire blight disease in 2022 was due to the dry weather during the flowering season. In other words, this yearly fluctuation in fire blight outbreaks was correlated with the presence or absence of rainfall and accumulated precipitation during the blossom infection risk period. This trend was observed across all surveyed regions where apples and pears were cultivated. Among the weather conditions influencing the blossom infection risk period, rainfall notably affected the activation of pathogens from over-wintering cankers and flower infections. In particular, precipitation during the initial 3 days of the blossom infection risk warning was confirmed as a decisive factor in determining the outbreak's scale.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.333-343
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• 2023

King oyster mushrooms are one of the major fresh agricultural products which their exports are increasing every year in Korea. Lycoriella ingenua, is notorious insect pest in agriculture, especially in mushroom production. Larvae of L. ingenua cause mainly direct crop damage and adults are vectors of several dangerous fungal pathogens. In this study, the effects of electron beam, X-ray, and gamma-ray irradiation on the development and reproduction of L. ingenua were evaluated. In addition, to find the optimal dose to control L. ingenua in a box filled with king oyster mushrooms, an empirical experiment was conducted for each radiation. As a result, the development and reproduction of L. ingenua were inhibited at 50 Gy for all electron beam, X-ray, and gamma-ray irradiation. Additionally, at the top, middle, and bottom of the export box filled with king oyster mushrooms, the development and reproduction of L. ingenua were inhibited by electron beam with 150 Gy, X-ray with 100 Gy, and gamma-ray with 50 Gy. These results can be provided as basic data for establishing an integrated quarantine management system when exporting mushrooms. It will also contribute to the safety of agricultural products and the strengthening of export competitiveness.