• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.201-209
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• 2006

Antifungal activities of 43 different plant oils were evaluated against different phytopathogenic fungi. Thyme oil showed highest antifungal activity among the tested oils. The major of thyme oil were found to be thymol, carvacrol, bomeol, p-cymene and linalool. Thymol and carvacrol were found to be responsible for thyme's antifungal activity. The spore germination assay was conducted on Alternaria mail and Botrytis cinerea. Thymol and carvacrol strongly inhibited spore germination in the fungi test. In addition, thymol and carvacrol showed a curative effectiveness to gray mold disease on cucumber crop. The antifungal activities of alkylphenol and alkylaniline compounds, which has similar molecular structure to that of thymol or cavacrol, were also tested. It was found that alkylphenol compounds also show higher inhibition to spore germination. Thus, thymol, carvacrol and alkylphenol compounds can be used an potent antifungal agents.

• Korean Journal of Plant Resources
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• v.30 no.4
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• pp.343-351
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• 2017

Plant extracts were screened for antifungal activity against major plant pathogens, Botrytis sp., Collectotrichum sp., Alternaria sp. and Cylindrocarpon sp. using 96-well microdilution method. Among the 662 methanol extracts from 401 plant species, 36 extracts showed complete inhibition of spore germination against at least one of four pathogenic fungi. Extracts of Morus alba twig and Sophora flavescens root showed minimum inhibition concentration (MIC) at $1,250{\mu}g/ml$ against Botrytis sp.. Extracts of Chloranthus japonicus root showed MIC at $1,250{\mu}g/ml$ against Collectotrichum sp.. Extracts of Glycyrrhiza uralensis aerial part, Inula helenium root and Menispermum dauricum root showed MIC between 625 and $1,250{\mu}g/ml$ against Alternaria sp.. G. uralensis aerial part and I. helenium root showed MIC at $1,250{\mu}g/ml$ against Cylindrocarpon sp.. Specifically, the extracts of Agrimonia pilosa root, Angelica tenuissima root, Asarum sieboldii root, Campsis grandifolia leaf and twig, Cnidium officinale root, Dictamnus dasycarpus root, G. uralensis aerial part, I. helenium root and M. alba twig completely inhibited spore germination at lower than $5,000{\mu}g/ml$ against all of four pathogenic fungi. Two methanol extracts from G. uralensis aerial part and M. alba twig may used as a candidate to develop into effective disease management materials in plant cultivation.

• Korean Journal Plant Pathology
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• v.13 no.1
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• pp.57-62
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• 1997

This experiment was conducted to test the control effect of methanol extracts of 10 medicinal plants on apple storage diseases caused by Botryosphaeria berengeriana, Glomerella cingulata and Penicillium expansum. Out of the 10 medicinal plants, methanol extracts of Coptis japonica and Anemarrhena asphodeloides inhibited effectively the mycelial growth of B. berengeriana, G. cingulata and P. expansum in vitro, for which the inhibition ratios of the two plant extracts were 100.0% and 89.3%, 73.7% and 94.1%, and 100.0% and 51.6%, respectively. Spore germination of the three fungi was inhibited 100% only by C. japonica extract, but only P. expansum was inhibited 100% by A. asphodeloides extract. No lesion was formed y the fungi at 5$^{\circ}C$ up to 2 weeks after inoculation. Lesion sizes produced by the three fungi at the temperature ranges of 1$0^{\circ}C$ to $25^{\circ}C$ and infection of B. berengeriana and G. cingulata were inhibited by C. japonica extract, but not by A. asphodeloides extract, while no lesion was formed by the fungi at 5$^{\circ}C$. Infections of the fungi on apples were somewhat stimulated by A. asphodeloides extract.

• Mycobiology
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• v.48 no.6
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• pp.484-494
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• 2020

Oak wilt disease caused by Raffaelea quercus-mongolicae has emerged obviously in Korea. We selected antifungal isolates against R. quercus-mongolicae among 368 endophytic fungal isolates from different parts of oak and pine trees. The experiment was conducted in the primary and secondary screenings by dual culture test. The antifungal activity of the selected isolates was assessed in culture filtrate test based on the inhibition rates in mycelial growth, sporulation, and spore germination of oak wilt fungus. Five isolates, E089, E199, E282, E409 and E415, showed strong antifungal activity in culture filtrate test, and their antifungal activity decreased on the culture media supplemented with heated culture filtrate. Higher mycelial growth inhibitions on the unheated media were recorded in E409 (Colletotrichum acutatum), E089 (Daldinia childiae), E415 (Alternaria alternata) and E199 (Daldinia childiae) with the inhibition rates of 79.0%, 70.1%, 68.9% and 64.5%, respectively. These isolates also had the higher sporulation inhibitions on unheated media with the rates of 96.8%, 84.2%, 82.8% and 80.5%, respectively. The spore germination of the oak wilt fungus was completely inhibited by E282 (Nectria balsamea) on both unheated and heated media. These results showed that a higher number of potent antifungal isolates against oak wilt fungus was isolated from the petiole compared to the other parts. This study could contribute to the development of biological control approaches for the management of oak wilt disease caused by R. quercus-mongolicae.

• BMB Reports
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• v.42 no.1
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• pp.47-52
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• 2009

Alanine racemase catalyzes the interconversion of L-alanine and D-alanine and plays a crucial role in spore germination and cell wall biosynthesis. In this study, alanine racemase produced by Bacillus anthracis was expressed and purified as a monomer in Escherichia coli and the importance of lysine 41 in the cofactor binding octapeptide and tyrosine 270 in catalysis was evaluated. The native enzyme exhibited an apparent $K_m$ of 3 mM for L-alanine, and a $V_{max}$ of $295\;{\mu}moles/min/mg$, with the optimum activity occurring at $37^{\circ}C$ and a pH of 8-9. The activity observed in the absence of exogenous pyridoxal 5'-phosphate suggested that the cofactor is bound to the enzyme. Additionally, the UV-visible absorption spectra indicated that the activity was pH independece, of VV-visible absorption spectra suggests that the bound PLP exists as a protonated Schiff's base. Furthermore, the loss of activity observed in the apoenzyme suggested that bound PLP is required for catalysis. Finally, the enzyme followed non-competitive and mixed inhibition kinetics for hydroxylamine and propionate with a $K_i$of $160\;{\mu}M$ and 30 mM, respectively.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.119-122
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• 1994

Effects of organophosphorus fungicides on cutinase activity from Glomerella cingulata causing apple anthracnose and infection of apple were investigated. Diisoprophylfluorophosphate (DFP) inhibited the enzyme activity indicating that catalysis involves an active serine. In inhibition of the enzyme activity by organophosphorus fungicides, I50 (molar concentration of fungicide at which the enzyme activity is inhibited 50%) of Hinosan and Kitazin P were 26.3 $\mu$M and 427.7 $\mu$M, respectively. At concentration of 10-3 M DFP and organophosphorus fungicides, the infection of G. cingulata was inhibited to 5% in comparison with 15% infection at the unwounded healthy control, but increased to 30% when added with 1 mg/ml of cutinase. Mycelial growth was 36 mm in colony diameter on the medium added with 10-4M of hinosan in comparison with 90 mm of the untreated control, but was 90 mm on the medium added with 10-4M of kitazin P showing lower inhibition than hinosan. The spore germination was more than 60% at all the concentrations of both fungicides.

• Mycobiology
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• v.30 no.1
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• pp.55-56
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• 2002

The 4',7-dimethoxyisoflavone was isolated from the leaves of Albizzia lebbeck for the first time. This flavonoid showed antifungal activity against some plant pathogenic fungi tested in vitro, e.g., Alternaria melongenae, A. brassicicola, A. brassicae, Curvularia maculans, C. pallescens, C. lunata, Curvularia species, Colletotrichum species, Helminthosporium penniseti and H. speciferum. The sensitivity of different fungi to this chemical varied considerably. A. brassicae was most sensitive as complete inhibition of germination was observed in all the concentrations(100 to 1000 ppm) of the chemical. Similar effect on H. speciferum and Curvularia species was also recorded at 500 ppm, whereas H. penniseti did not germinate at 250 ppm. A. melongenae and A. brassicicola also did not germinate at 1000 ppm while 750 ppm was inhibitory to C. lunata and C. maculans. Germination in almost all fungi was significantly inhibited at each concentration in comparison to control except Curvularia sp. and H. speciferum. Use of 4',7-dimethoxyisoflavone to control some plant diseases under field conditions has been suggested.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.325-327
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• 2012

Experiments for growth inhibition of two different plant pathogenic fungal species, Alternaria alternata (KCTC26781) and Fusarium graminearum ZO3639 (type culture) and ASR1R1 (isolate from rice), by a chitinase (Chi2) expressed in the autolysing tissue of Coprinellus congregatus were carried out. In liquid media, Chi2 ($50{\mu}g/ml$) inhibited more than 90% of germination of A. alternata spore, and the growth of each fungal strain was totally inhibited by the addition of Chi2 at the concentrations of $70{\mu}g/ml$. When $6{\mu}g$ of Chi2 was added twice a day at the hyphal tip zone, both strains of F. graminearum showed growth inhibition as well as decreased hyphal branching.

• The Korean Journal of Mycology
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• v.22 no.1
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• pp.50-61
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• 1994

From soil samples, 380 antagonistic microorgnisms were isolated. Among the isolates, 42 strains had mycelia growing inhibition ability against Fusariun solani, ginseng root rot causing pathogen. Isolates CHA 1 and S-PFHR 6 were proposed as antagonists for this study and they were identified as Promicromonospora sp. and Pseudomonas pseudoalcaligenes respectively. As an antagonism against hyphae of F. solani in dual culture test, CHA 1 and S-PFHR 6 inhibited linear growing, caused abnormal branching, and the membrane projection which formed by cell wall destruction. The secondary metabolites contained in the culture filtrates which prepared from PD broth and Nutrient broth inhibited the spore germination to 14.3%. The culture filtrate of S-PFHR 6 which prepared by a little amount of soil extract addition to nutrient rich medium had more strongly. inhibited the spore germination and spore germination decreased to less than 4.0% in it. The soil used in this study had fungistasis and the germination rate of macroconidia and chlamydospore of F.solani was 19.4% and 17.7% respectively. The steam sterilized soil lost fungistasis and germination rate of conidia increased to more than 97.9%. The soils amended with the propagule of CHA 1 and S-PFHR 6 increased fungistasis and the germination rate of macroconidia decreased to 14.7% and 11.7% respectively in each treatments. But the soil ammended with glucose and asparagine annulled fungistatic ability and the germination rate of macroconidia increased to more than 48.0%. As an antagonistic activity of the secondary metabolites of two antagonistic isolates in soil, the germination rate of macroconidia of F. solani was 9.3% in the soil amended with the culture filtrate of CHA 1 but the culture filtrate of S-PFHR 6 had no such activity. In the soil which treated with antagonist propagule or culture filtrate, the chlamydospore germination rate was lower than that in natural soil. The addition of glucose and asparagine to antagonist propagule treated soil did not enhanced the chlamydospore germination.

• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.1103-1108
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• 2016

Yam anthracnose caused by Colletotrichum gloeosporioides (C.g) is the most devastating disease of yam (Dioscorea sp.). In the present study, we evaluated the culture filtrate extract (CFE) of azalomycin-producing Streptomyces malaysiensis strain MJM1968 for the control of yam anthracnose. MJM1968 showed strong antagonistic activity against C.g in vitro. Furthermore, the MJM1968 CFE was tested for inhibition of spore germination in C.g, where it completely inhibited spore germination at a concentration of 50 μg/ml. To assess the in planta efficacy of the CFE and spores of MJM1968 against C.g, a detached leaf bioassay was conducted, which showed both the treatments suppressed anthracnose development on detached yam leaves. Furthermore, a greenhouse study was conducted to evaluate the CFE from MJM1968 as a fungicide for the control of yam anthracnose. The CFE non-treated plants showed a disease severity of >92% after 90 days of artificial inoculation with C.g, whereas the disease severity of CFE-treated and benomyl-treated yam plants was reduced to 26% and 15%, respectively, after 90 days. Analysis of the yam tubers from the CFE-treated and non-treated groups showed that tubers from the CFE-treated plants were larger than that of non-treated plants, which produced abnormal smaller tubers typical of anthracnose. This study demonstrated the utility of the CFE from S. malaysiensis strain MJM1968 as a biofungicide for the control of yam anthracnose.