• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.149-152
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• 2006

Construction of focused library of 2-benzylimino-1,3-thiazolines 7 through molecular modification of 3-alkyl-2-phenylimino-1,3-thiazolines 1 which showed selective fungicidal activity against rice blast and their fungitoxic activity against 6 kinds of typical plant diseases was described. Fifty four compounds of focused library of 2-benzylimino-1,3-thiazolines 7 were synthesized from the reaction of the corresponding $\gamma$-chloroacetoacetanilides 6 with N-benzyl thioureas 5 by parallel synthetic methodology. As results of fungicidal screening against the typical plant diseases, twenty eight kinds of 7 at 100 ${\mu}g$ $mL^{-1}$ showed the control value over 50% against tomato late blight.

• The Korean Journal of Pesticide Science
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• v.2 no.2
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• pp.22-28
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• 1998

Twenty six derivatives of bis-aromatic ${\alpha},{\beta}$-unsaturated ketones as substrate(S) were synthesized and their fungicidal activities in vivo against rice blast(Pyricularia oryzae), tomato leaf blight(Phytophtora infestans) and barley powdery mildew(Erysiphe graminis) were examined. The quantitative structure-activity relationship(QSAR) between the fungicidal activities($pI_{50}$) and a physicochemical parameters of substitued($R_{2}$) phenyl backbone group in 2-thienyl and 2-furyl substituents were analyzed with regression equations. The activities of substituted($R_{2}$) phenyl backbone in 2-thienyl substituents, $1{\sim}10$ would depend largely on the resonance(R>0), molecular refractivity($M_{R}<0$) and optimal length of substituent(($L_{1})opt.=5.50{\AA}$). Whereas, in case of 2-furyl substituents, $10{\sim}26$ optimal molar attraction constant ($F_{opt}=0.49{\sim}l.11$), optimal steric($Es_{opt}=1.78$) constant and indicator variables(Io & Ip) for position of substituents. The fungicidal activity relationship of 2-thienyl substituents against Pyricularia oryzae and Phytophtora infestans have been a reciprocal proportioned.

• The Korean Journal of Pesticide Science
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• v.2 no.1
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• pp.24-31
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• 1998

Chemical derivative synthesis of ricinine, an active compound of Ricinus communis which showed high mortality against brown planthopper (Nilaparvata lugens), was performed to improve its pesticidal activity and the toxicity of 12 synthetic derivatives against major insect pests and phytopathogenic fungi were examined. Carbamate derivatives of ricinine could be synthesized from the precursor of ricinine, chloronorricinine and norricinine, whereas the derivatives were not synthesized from chlororicinic acid and ricinic acid having ketone group of pyridine ring. In organophosphates, reaction with oxon type of phosphate gave better yield than thiono type. Among the organophosphate derivatives of ricinine, thiono type of derivative structure gave $96.3%{\sim}100%$ mortality of the brown planthopper and the two-spotted spider mite (Tetranychus urticae) at 500 ${\mu}g/ml$ level. On the other hand, carbamate derivatives did not show insecticidal activity. In the fungicidal activity of ricinine derivatives, the derivative having amino radical at the 2 position of ricinine gave 85 to 100% of mycelium growth inhibition effect against ten major plant pathogens at the 200 ${\mu}g/ml$ level. In particular, the control value of the derivative on the rice blast (Pyricularia grisea) and barley powdery mildew (Erysiphe graminis) at the 250 ${\mu}g/ml$ level in vivo under greenhouse conditions was 92% and 96%, respectively.

• Research in Plant Disease
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• v.15 no.3
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• pp.222-229
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• 2009

A Pseudomonas strain SG3 producing biosurfactant and showing antifungal and insecticidal activities was isolated from agricultural soil severely contaminated with machine oils. The antagonistic bacterium inhibited mycelial growth of all of the tested fungal pathogens. The fermentation broth of SG3 also effectively suppressed the development of various plant diseases including rice blast, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose. An antifungal substance was isolated from the fermentation broth of SG3 by ethyl acetate partitioning, silica gel column chromatography and preparative HPLC under the guide of bioassay. The chemical structure of the antifungal substance was determined to be rhamnolipid B by mass and NMR spectral analyses. The antifungal biosurfactant showed a potent in vivo antifungal activity against gray mold and late blight on tomato plants. In addition, rhamnolipid B inhibited mycelial growth of B. cinerea causing tomato gray mold and zoospore germination and mycelial growth of P. infestans causing tomato late blight. Pseudomonas sp. SG3 producing rhamnolipid B could be used as a new biocontrol agent for the control of plant diseases occurring on tomato plants.

• Korean journal of applied entomology
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• v.28 no.2
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• pp.61-68
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• 1989

To investigate the possibility of the BPH control by systematic application of insecticides, biological effects of buprofezin and isoprothiolane upon the BPH population was evaluated in the laboratory and pot. Both chemicals did not affect the developmental period of the nymphal stage with the applied dosages. When the buprofezin treated instar nymph was developed to the adult, adult's longevity was fairly reduced and such an effect of buprofezin was greater upon the younger instar nymphs. Residual effect of buprofezin was about 30 days in the pot. And it could suppress the BPH population when the younger instar nymphs were dominant age group in the population at the time of treatment. Isoprothiolane was also more effective for the suppression of the BPH population when the younger instar nymphs were dominant at the time of treatment. And it was expected that by buprofezin treatment in July the control effect of isoprothiolane against the BPH population could be maximized when it was treated to control the rice neck blast in late July or early August, because buprofezin could induce the biased population age distribution in which younger instar nymphs were main group at the time of isoprothiolane treatment.

• Korean journal of applied entomology
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• v.13 no.1 s.18
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• pp.19-23
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• 1974

Since Tongil has been cultivated widely in farmers' fields, the variety is known to be highly resistant to existing races of Pyricularia oryzae in Korea. However, Tongil and the sister lines were moderately susceptible to race IA-65, which was isolated from Tongil at the blast nursery of the College of Agriculture, Seoul National University, 1972. In field tests of 1973, pathogenic reactions of IR lines at the isolated nursery, where IA-65 had been inoculated, were significantly higher than those at the farm nursery. When seedlings of 196 IR lines were inoculated with IA­65, about $30\%$ of the IR lines including IR667-98 were moderately susceptible. Among the 30 isolates of P. oryzae obtained mostly from indicas, 12 were also differentiated in 1973 as IA group known to be the most prevalent races at IRRI in the Philippines, where Tongil has been highly susceptible. This IA group was also pathogenic to Tongil in greenhouse experiments. The race group causing moderately susceptible to Tongil should be new in Korea, since no occurrences of the race IA have ever been reported previously from the areas where japonica types of rice are cultivated. Because some races of P. oryzae present in Korea are pathogenic to Tongil and because these races may become prevalent in the fields, the reaction of Tongil must be continuously monitored.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.112-118
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• 1987

This experiment was conducted to obtain the basic information for the effective control of rice blast. Eleven races of Pyricuiaria oryzae were identified, 5 races of KJ group and 6 races of KI group in Kyungpook province. Among them KJ301 was the most dominant one, and they were prevailed in the order of KJ401, KJ201, KJ101, KJ105, KI307 and $KI315^b$. The distribution ratio of KI group race was higher in the middle and northern region than the southern and coastal region. A positive correlation was found between the distribution ratio of KI group races and cultivated area of indica type cultivals. The total ratio of Blasticidin-S resistant isolates in P. oryzae was 31.2%. The distribution ratios of resistant isolates were 43.2% in the southern region, 29.4% middle, 25.0% nothern and 10.5% coastal region, respectively. The distribution ratio of Blasticidin-S resistant Isolates was correlated positively with amounts of the chemical sprayed, but not correlated with the race of P. oryzae.

• The Plant Pathology Journal
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• v.39 no.4
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• pp.361-373
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• 2023

In plant-pathogen interactions, Magnaporthe oryzae causes blast disease on more than 50 species of 14 monocot plants, including important crops such as rice, millet, and most 15 recently wheat. M. oryzae is a model fungus for studying plant-microbe interaction, and the main source for fungal pathogenesis in the field. Here we report that MoJMJD6 is required for conidium germination and appressorium formation in M. oryzae. We obtained MoJMJD6 mutants (ΔMojmjd6) using a target gene replacement strategy. The MoJMD6 deletion mutants were delayed for conidium germination, glycogen, and lipid droplets utilization and consequently had decreased virulence. In the ΔMojmjd6 null mutants, global histone methyltransferase modifications (H3K4me3, H3K9me3, H3K27me3, and H3K36me2/3) of the genome were unaffected. Taken together, our results indicated that MoJMJD6 function as a nuclear protein which plays an important role in conidium germination and appressorium formation in the M. oryzae. Our work provides insights into MoJMJD6-mediated regulation in the early stage of pathogenesis in plant fungi.

• The Korean Journal of Mycology
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• v.32 no.1
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• pp.31-38
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• 2004

An endophytic bacterial strain EB215 that was isolated from cucumber (Cucumis sativus) roots displayed a potent in vivo antifungal activity against Colletotrichum species. The strain was identified as Burkholderia cepacia based on its physiological and biochemical characteristics, and 16S rDNA gene sequence. Optimal medium and incubation period for the production of antifungal substances by B. cepacia EB215 were nutrient broth (NB) and 3 days, respectively. An antifungal substance was isolated from the NB cultures of B. cepacia EB215 strain by centrifugation, n-hexane partitioning, silica gel column chromatography, preparative TLC, and in vitro bioassay. Its chemical structure was determined to be pyrrolnitrin by mass and NMR spectral analyses. Pyrrolnitrin showed potent disease control efficacy of more than 90% against pepper anthracnose (Colletotrichum coccodes), cucumber anthracnose (Colletotrichum orbiculare), rice blast (Magnaporthe grisea) and rice sheath blight (Corticium sasaki) even at a low concentration of $11.1\;{\mu}g/ml$. In addition, it effectively controlled the development of tomato gray mold (Botrytis cinerea) and wheat leaf rust (Puccinia recondita) at concentrations over $33.3\;{\mu}g/ml$. However, it had no antifungal activity against Phytophthora infestans on tomato plants. Further studies on the development of microbial fungicide using B. cepacia EB215 are in progress.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.16-23
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• 2005

In order to develop a new microbial fungicide using endophytic bacteria for the control of anthracnoses occurring on various crops, a total of 260 bacterial strains were isolated from fresh tissues of 5 plant species. After they were cultured in broth medium, their antifungal activities were tested for in vivo antifungal activity against cucumber anthracnose caused by Colletotrichum orbiculare. As the results, liquid cultures of 28 strains showed potent antifungal activities more than $90\%$ against cucumber anthracnose. At 3-fold dilutions of liquid cultures, 18 strains inhibited the development of cucumber anthracnose of more than $70\%$. They were further tested for in vivo antifungal activity against red pepper anthracnose caused by C. coccodes and in vitro antifungal activity against C. acutatum, a fungal agent causing red pepper anthracnose. Among 18 strains, a bacterial strain EB215 isolated from cucumber roots displayed the most potent antifungal activity against Colletotrichum species. It was identified as Burkholderia cepacia based on its physiological and biochemical characteristics, Biolog test and 16S rDNA gene sequence. It also controlled effectively the development of rice blast (Magnaporthe grisea), rice sheath blight (Corticium sasaki), tomato gray mold (Botrytis cinerea), and tomato late blight (Phytophthora infestans). Studies on the characterization of antifungal substances produced by B. cepacia EB215 are in progress.