• The Korean Journal of Mycology
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• v.41 no.2
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• pp.118-126
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• 2013

The experiment was carried out to analyze the inhibition effect of plant pathogenic fungi and growth promotion activity induced by the bacterial strains isolated from peatmoss. Among the isolated bacterial strains, B10-2, B10-4, B10-5 and B10-6 which showed more than 30% inhibition rate against Botrytis cinerea and Rhizoctonia solani in vitro, were further analyzed in the greenhouse for the growth promotion activity on lettuce (Lactuca sativa), pak-choi (Brassica compestris L. ssp. chinensis) and Chinese cabbage (Brassica campestris L. ssp. pekinensis). The results showed the treatment of B10-4 on lettuce showed the highest growth promotion activity with the leaf area ($169.17cm^2$), fresh weight (leaf: 40.29 g, root: 8.80 g)and dry weight (leaf: 11.24 g, root: 4.17 g), which was about two folds as compared to control. On pak-choi, the growth promotion rate was the highest with the leaf area of $112.87cm^2$, leaf fresh weight of 60.70 g, root fresh weight of 3.37 g, leaf dry weight of 14.34 g, and root dry weight of 1.90 g. As a result of treatment of B10-13 on chinese cabbage, the growth promotion rate was the highest with the leaf area ($293.56cm^2$), fresh weight (leaf: 113.67 g, root: 2.40 g) and dry weight (leaf: 6.03 g, root: 0.53 g). The production of Indole Acetic Acid (IAA) and Indole-3-Butylic Acid (IBA) were also analyzed in these bacterial isolates. The IAA and IBA analyses were carried out in all bacterial isolates each day within the 5 days of incubation period. The highest production of IAA was observed with $112.57{\mu}g/mg$ protein in B10-4 after 3 days of incubation and IBA production was the highest in B10-2 with $58.71{\mu}g/mg$ protein after 2 days of incubation. Also, phosphate solubilizing activity was expressed significantly in B10-13 in comparison to that of other bacterial isolates. Bacterial identification showed that B10-2 was Bacillaceae bacterium and B10-5 was Bacillus cereus, B10-4 and B10-6 were Bacillus sp. and B-13 was Staphylococcus sp. by ITS sequence.

• Journal of Ginseng Research
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• v.46 no.6
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• pp.790-800
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• 2022

Background: Panax ginseng Meyer is one of the most valuable medicinal plants which is enriched in anti-microbe secondary metabolites and widely used in traditional medicine. Botrytis cinerea is a necrotrophic fungus that causes gray mold disease in a broad range of hosts. B. cinerea could overcome the ginseng defense and cause serious leaf and root diseases with unknown mechanism. Methods: We conducted simultaneous transcriptomic and metabolomic analysis of the host to investigate the defense response of ginseng affected by B. cinerea. The gene deletion and replacement were then performed to study the pathogenic gene in B. cinerea during ginseng - fungi interaction. Results: Upon B. cinerea infection, ginseng defense responses were switched from the activation to repression, thus the expression of many defense genes decreased and the biosynthesis of antifungal metabolites were reduced. Particularly, ginseng metabolites like kaempferol, quercetin and luteolin which could inhibit fungi growth were decreased after B. cinerea infection. B. cinerea quercetin dioxygenase (Qdo) involved in catalyzing flavonoids degradation and ∆BcQdo mutants showed increased substrates accumulation and reduced disease development. Conclusion: This work indicates the flavonoids play a role in ginseng defense and BcQdo involves in B. cinerea virulence towards the P. ginseng. B. cinerea promotes disease development in ginseng by suppressing of defense related genes expression and reduction of antifungal metabolites biosynthesis.

• Mycobiology
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• v.49 no.3
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• pp.249-257
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• 2021

Plants pollination are conducted through various pollinators such as wind, animals, and insects. Recently, the necessity for artificial pollination is drawing attention as the proportion of natural pollinators involved is decreasing over the years. Likewise, the trade in pollen for artificial pollination is also increasing worldwide. Through these imported pollens, many unknown microorganisms can flow from foreign countries. Among them, spores of various fungi present in the particles of pollen can be dispersed throughout the orchard. Therefore, in this study, the composition of fungal communities in imported pollen was revealed, and potential ecological characteristics of the fungi were investigated in four types of imported pollen. Top 10 operational taxonomic unit (OTU) of fungi were ranked among the following groups: Alternaria sp., Cladosporium sp., and Didymella glomerata which belong to many pathogenic species. Through FUNGuild analysis, the proportion of OTUs, which is assumed to be potentially plant pathogens, was higher than 50%, except for apple pollen in 2018. Based on this study of fungal structure, this information can suggest the direction of the pollen quarantine process and contribute to fungal biology in pollen

• The Plant Pathology Journal
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• v.40 no.2
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• pp.218-224
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• 2024

Plants are treasure trove of novel compounds that have potential for antifungal chemicals and drugs. In our previous study, we had screened plant extracts obtained from more than eight hundred plant materials collected in Korea, and found that butanol fraction of the Actinostemma lobatum were most potent in suppressing growth of diverse fungal pathogens of plants. Here in this study, we describe further analysis of the butanol fraction, and summarize the results of subsequent antifungal activity test for the sub-fractions against a selected set of plant pathogenic fungi. This line of analyses allowed us to identify the sub-fractions that could account for a significant proportion of observed antifungal activity of initial butanol fraction from A. lobatum. Further analysis of these sub-fractions and determination of structure would provide the shortlist for novel compounds that can be a lead to new agrochemicals.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.212-219
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• 2016

Forty-nine pigments were extracted from the collections of 106 pigment producing bacteria from the plant rhizosphere soil. Antibacterial activity test was performed in the subjects of the extracted pigments with plant pathogenic bacteria including Xanthomonas axonopodis and Xanthomonas campestris, and with plant pathogenic fungi including Botrytis cinerea, Colletotrichum acutatum, and Fusarium oxysporum. The yellow pigment by Chryseobacterium sp. RBR9 and the red pigment by of Methylobacterium sp. RI13 showed the antibacterial activities against Xanthomonas axonopodis and Xanthomonas campestris. The violet pigment by Collimonas sp. DEC-B5 showed the antibacterial activity as well as the antifungal activities against Botrytis cinerea and Fusarium oxysporum. Especially, the violet pigment inhibited the growth of Botrytis cinerea more than 65% at MIC $20{\mu}M$. Upon the HPLC analysis result for the isolation of pigment with antifungal activity, violacein (91.6%) and deoxyviolacein (8.4%) were isolated for the pigment by Collimonas sp. DEC-B5. The production amount of the pigment was increased more than 10 times higher when D-mannitol 1.5% and yeast extract 0.2% were added as the nitrogen source to SCB medium. This study suggests that produced violacein by Collimonas sp. DEC-B5 will be effective to control strawberry gray-mold rot fungi by its preventive activity.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.249-261
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• 2006

Fifty compounds such as ester, sulfonyl ester, carbamate, ether and phosphoyl ester derivatives of 4-isopropyl-3-methylphenol(I) and 5-isopropyl-3-methylphenol(II) were synthesized. These derivatives were identified by IR, GC/MS and $^1H$-NMR spectra. Their in vitro antifungal activities were tested against 10 plant pathogenic fungi. Among them, several compounds showed potent in vitro antifungal activity. The selected compounds showing potent in vitro antifungal activity were tested for their in vivo antifungal activities against 5 plant diseases such as rice blast, rice sheath blast, cucumber anthracnose, cucumber gray mold and tomato late blight. As a result, 4-isopropyl-3-methylphenyl(2-amino-thiazole-4-yl)methoxyiminoacetate(I-7a) showed a potent in vivo antifungal activity against rice blast. Both methyl (4-isopropyl-3-methylphenoxy)acetate(I-4d) and methyl (5-isopropyl-3-methylphenoxy)acetate(II-4d) effectively inhibited the development of cucumber gray mold.

• Research in Plant Disease
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• v.12 no.1
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• pp.51-54
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• 2006

The effectiveness of four plant oils (garlic, ginger, cinnamon and lemongrass) against a range of plant pathogenic organisms was tested in vitro. Of the four oils, two oils (garlic and cinnamon) showed relatively good antimicrobial activities. Activity of garlic oil was shown against the plant pathogenic bacteria Agrobacterium tumefaciens, Ewinia carotovora, Ralstonia solanacearum, Xanthomonas campestris, and the fungi Phytophthora infestans, Fusarium oxysporum, Collectotricum sp., whereas Acidovorax avenae and Pythium sp. showed the resistance towards garlic oil. Results from the planta bioassays under greenhouse conditions indicated that garlic oil significantly reduced the cucumber powdery mildew (Sphaerotheca fusca) and tomato powdery mildew (Erysiphe cichoracearum) showing control value 70.0-74.6% and 71.2%, respectively.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.593-602
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• 2022

Anthracnose, caused by the ascomycete fungus Colletotrichum scovillei, is a destructive disease in pepper. The fungus germinates and develops an infection structure called an appressorium on the plant surface. Several signaling cascades, including cAMP-mediated signaling and mitogen-activated protein kinase (MAPK) cascades, are involved in fungal development and pathogenicity in plant pathogenic fungi, but this has not been well studied in the fruit-infecting fungus C. scovillei. Ste50 is an adaptor protein interacting with multiple upstream components to activate the MAPK cascades. Here, we characterized the CsSTE50 gene of C. scovillei, a homolog of Magnaporthe oryzae MST50 that functions in MAPK cascades, by gene knockout. The knockout mutant ΔCsste50 had pleiotropic phenotypes in development and pathogenicity. Compared with the wild-type, the mutants grew faster and produced more conidia on regular agar but were more sensitive to osmotic stress. On artificial and plant surfaces, the conidia of the mutant showed significantly reduced germination and failed to form appressoria. The mutant was completely non-pathogenic on pepper fruits with or without wounds, indicating that pre-penetration and invasive growth were both defective in the mutant. Our results show that the adaptor protein CsSTE50 plays a role in vegetative growth, conidiation, germination, appressorium formation, and pathogenicity in C. scovillei.

• Journal of the Korean Applied Science and Technology
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• v.41 no.2
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• pp.199-207
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• 2024

We conducted to investigate both plant growth-promoting and plant disease-controlling activities of bacterial strains isolated from soil. Among the 48 isolated strains, SH-23, SH-26, SH-29, and SH-33 were identified as excellent strains for the production of β-glucosidase, cellulase, amylase, and protease. These 4 strains exhibited antifungal activity against plant pathogenic fungi (Botrytis cinerea, Rhizoctonia solani, Fusarium oxysporum, Colletotrichum acutatum). Strain SH-26, which exhibited excellent organic matter decomposition and antifungal activity against plant pathogenic fungi, was selected as the final superior strain. Upon determining the 16S rRNA gene sequence of the selected SH-26 strain, it exhibited 100% similarity with Pseudomonas knackmussii HG322950 B13^T, Pseudomonas citronellolis BCZY01000096 NBRC 103043^T, and Pseudomonas delhiensis jgi.1118306 RLD-1^T. Furthermore, it was confirmed that the Pseudomonas sp. SH-26 exhibited siderophore production, nitrogen fixation ability, and the production of Indole-3-acetic acid.

• The Plant Pathology Journal
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• v.16 no.1
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• pp.52-54
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• 2000

Pitch canker of Pinus rigida, caused by Fusarium subglutinans f. sp. pini, was first noticed in Inchon, Korea, and is now being spread into other plantations of pines. Typical symptoms re resin flows from canders on the shoots, branches, and trunks, and resin-soaking of the sap wood under the bark. Pathogenic fungi were isolated from the infected shoots, branches, and sees on Fusarium-selective medium. Mycelial growth and microscopic characteristics were examined. Pathogenicity test was carried out by inoculating four common species of pines (P. rigida, P. densiflora, P. thunbergii, and P. koraiensis) in Korea. P. rigida and P. thunbergii showed symptoms identical to those of naturally infected trees, while P. densiflora and P. koraiensis remained free symptomless.