• The Korean Journal of Mycology
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• v.22 no.1
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• pp.31-35
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• 1994

Coprinus cinereus resistant strain against validamycin was successfully isolated. Germination rate of oidiospores, branching pattern, and localization of actin protein of the resistant strain were compared with normal strain. The resistant strain showed better germiantion rate of oidia (about 20 fold), more frequent branching, and even actin localization on validamycin plate where actin content was severely reduced in case of normal strain.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1311-1315
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• 2006

Aminocyclitol antibiotic validamycin A, a prime control agent for sheath blight disease of rice plants, is biosynthesized by Streptomyces hygroscopicus var. limoneus. Within the validamycin biosynthetic gene cluster, vldBC forms an operon of vldABC with vidA, the gene encoding 2-epi-5-epi-valiolone synthase. Biochemical studies, employing the recombinant proteins from Escherichia coli, established VldB and VldC as D-glucose $\alpha$-1-phosphate uridylyltransferase and glucokinase, respectively. This finding substantiates that the validamycin biosynthetic gene cluster harbors genes encoding the enzymes for UDP-glucose formation from glucose. Therefore, we propose that validamycin biosynthesis employs its own catalysts to generate UDP-glucose, but not depending on the primary metabolism.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.35-40
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• 2005

Damping-off of summer spinach caused by Rhizoctonia solani AG-4 has become a very important disease. For the control of summer spinach damping-off, antifungal activity of thirteen fungicides (pencycuron, trifloxystrobin, pyraclostrobin, azoxystrobin, kresoxim-methyl, validamycin, fluazinam, Benlate-T, flutolanil, cyazofamid, hexaconazole, tebuconazole, prochloraz) were evaluated in vitro and in vivo. Pencycuron, pyraclostrobin, validamycin, fluazinam, Benlate-T, hexaconazole, tebuconazole, and flutolanil significantly suppressed the mycelial growth of the pathogenic fungus. However, trifloxystrobin, azoxystrobia kresoxim-methyl, cyazofamid, and prochloraz did not represent good inhibition on the growth of R. solani. When applied by soil drenching (2,000 mg/L), pencycuron, pyraclostrobin, validamycin, fluazinam, Benlate-T, and flutolanil provided spinach survival ratios of 97.8%, 84.4%, 93.3%, 95.6%, 91.1%, and 86.7%, respectively. Also when treated in seed at 2,000 ing/L, pencycuron and pyraclostrobin displayed survival ratios of more than 85.1%.

• Research in Plant Disease
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• v.29 no.2
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• pp.168-173
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• 2023

Agricultural antibiotics are widely used to inhibit the growth of phytopathogenic bacteria involved in plant diseases. However, continuous antibiotic overuse in crop production may lead to the development of antibiotic resistance in phytopathogenic bacteria. This study was conducted to evaluate the resistance to three different agricultural antibiotics (oxytetracycline+streptomycin, streptomycin, and validamycin A) in 91 strains of phytopathogenic bacteria including Pectobacterium carotovorum, Pseudomonas syringae pv. actinidiae, Clavibacter michiganensis subsp. michiganensis, C. michiganensis subsp. capsici, and Xanthomonas arboricola pv. pruni. Bacterial growth in the presence of various concentrations of validamycin A was also assessed spectrophotometrically by analyzing the optical density. All strains did not grow when the cells were exposed to oxytetracycline+streptomycin or 100× of streptomycin. However, among the 91 strains, 4% and 2% strains showed bacterial growth at the concentrations of 1× and 10× of streptomycin, respectively. Furthermore, 97%, 93%, and 73% strains were resistant to the 1×, 10×, and 100× of validamycin A, respectively, and especially, P. carotovorum contained the highest resistance to the validamycin A. Minimum bactericidal concentration values of validamycin A did not correlate with the patterns of agricultural antibiotic resistance. Further studies are needed to understand the incidence and development of antibiotic resistance in phytopathogenic bacteria.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.287-294
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• 2015

In Korea, Strawberry bacterial angular leaf spot disease was first reported in 2010. The disease of strawberry caused serious problem for strawberry producers and export. To field test, we applied the bactericides in June and October as nursery stage and cultivation stage, respectively. In nursery stage with high temperature condition, Oxolinic acid (97.2%) showed significant control effect. In cultivation stage with low temperature condition is soil sterilization and soil non- sterilization the control effect. In cultivation stage in soil sterilization stage Validamycin (93.3%) showed reliable control effect against the disease. Also, soil non-sterilization stage with low control effect of Validamycin (80%) showed control effect the lower than a soil sterilization stage.

• Korean journal of applied entomology
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• v.17 no.3 s.36
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• pp.143-147
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• 1978

1. The trials were planned to test ten different fungicides for the control of ginseng damping off Caused by Rhizoctonia solani in the laboratory and in the field. 2. Fungicidal activity was tested by soil drenching in test tube in the laboratory and with seedlings in t he seedbed naturally and artificially infested with damping-off organisms. 3. Promising chemicals to control damping-off of ginseng without marked phytotoxicity were Homai, Captan, Validamycin and Tachigaren.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.22-29
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• 2019

Validamycin A is an aminoglycoside fungicide produced by Streptomyces hygroscopicus that inhibits trehalase. The purpose of this study was to develop a method for detecting validamycin A in agricultural samples to establish MRL values for use in Korea. The validamycin A residues in samples were extracted using methanol/water (50/50, v/v) and purified with a hydrophilic-lipophilic balance (HLB) cartridges. The analyte was quantified and confirmed by liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Matrix-matched calibration curves were linear over the calibration ranges (0.005~0.5 ng) into a blank extract with $R^2$ > 0.99. The limits of detection and quantification were 0.005 and 0.01 mg/kg, respectively. For validation validamycin A, recovery studies were carried out three different concentration levels (LOQ, $LOQ{\times}10$, $LOQ{\times}50$, n = 5) with five replicates at each level. The average recovery range was from 72.5~118.3%, with relative standard deviation (RSD) less than 10.3%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the NIFDS (National Institute of Food and Drug Safety) guideline (2016). Therefore, the proposed analytical method is accurate, effective and sensitive for validamycin A determination in agricultural commodities.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2001.06a
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• pp.98-98
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• 2001

• Research in Plant Disease
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• v.21 no.4
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• pp.255-260
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• 2015

We investigated influence of three commercial antibiotics viz., oxolinic acid, streptomycin, and validamycin A, on biocontrol and plant growth promoting activities of Bacillus vallismortis EXTN-1 and BS07M in Chinese cabbage. Plants were pre-drenched with these strains followed by antibiotics application at recommended and ten-fold diluted concentration to test the effect on biocontrol ability against soft rot caused by Pectobacterium carotovorum SCC1. The viability of the two biocontrol strains and bacterial pathogen SCC1 was significantly reduced by oxolinic acid and streptomycin in vitro assay, but not by validamycin A. In plant trials, strains EXTN-1 and BS07M controlled soft rot in Chinese cabbage, and there was a significant difference in disease severity when the antibiotics were applied to the plants drenched with the two biocontrol agents. Additional foliar applications of oxolinic acid and streptomycin reduced the disease irrespective of pre-drench treatment of the PGPRs. However, when the plants were pre-drenched with EXTN-1 followed by spray of validamycin A at recommended concentration, soft rot significantly reduced compared to untreated control. Similarly, strains EXTN-1 and BS07M significantly enhanced plant growth, but it did not show synergistic effect with additional spray of antibiotics. Populations of the EXTN-1 or BS07M in the rhizosphere of plants sprayed with antibiotics were significantly affected as compared to control. Taken together, our results suggest that the three antibiotics used for soft rot control in Chinese cabbage could affect bacterial mediated biocontrol and plant growth promoting activities. Therefore, combined treatment of the PGPRs and the commercial antibiotics should be carefully applied to sustain environmental friendly disease management.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.383-383
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• 2005