• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.298-302
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• 2011

Bacterial wilt, caused by Ralstonia, solanacearum, is a very destructive disease to tomato plants (Solanum lycopersicum) in Korea. This study was undertaken to find out the growth inhibitory effect bactericides on bacterial wilt pathogen of streptomycin, oxytetracyclin streptomycin sulfate WP and significantly suppressed the growth of bacterial wilt pathogen. Copper hydroxide WP showed control value of 62.5%. Therefore, it is concluded that the bactericide used in this study showed strong inhibitory effect to tomato bacterial wilt and they can be recommend to control the disease. And also, Copper hydroxide WP may be effective for control of bacterial wilt of tomato in conventional culture, farming without agricultural and organic farming.

• The Plant Pathology Journal
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• v.23 no.4
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• pp.239-244
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• 2007

MicroTom is a miniature tomato plants with various properties that make it as a model system for experiments in plant molecular biology. To extend its utility as a model plant to study a plant - bacterial wilt system, we investigated the potential of the MicroTom as a host plant of bacterial wilt caused by Ralstonia solanacearum. We compared the disease progress on standard tomato and MicroTom by two inoculation methods, root dipping and soil drenching, using a race 1 strain GMI1000. Both methods caused the severe wilting on MicroTom comparable to commercial tomato plant, although initial disease development was faster in root dipping. From the diseased MicroTom plants, the same bacteria were successfully reisolated using semiselective media to fulfill Koch's postulates. Race specific and isolate specific virulence were investigated by root dipping with 10 isolates of R. solanacearum isolated from tomato and potato plants. All of the tested isolates caused the typical wilt symptom on MicroTom. Disease severities by isolates of race 3 was below 50 % until 15 days after inoculation, while those by isolates of race 1 reached over 50% to death until 15 days. This result suggested that MicroTom can be a model host plant to study R. solanacearum - plant interaction.

• Research in Plant Disease
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• v.17 no.3
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• pp.326-333
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• 2011

This study evaluated disease resistance responses of pure lines of tomato plants at various temperature conditions against Ralstonia solanacearum strains isolated from Korea. Evaluation of six tomato lines with various strains of R. solanacearum showed that many strains can infect the resistant lines of tomato plants previously known as highly tolerant to bacterial wilt. One of the most virulent strains, SL341 (race 1 and biovar 4) caused severe infection on all six tomato lines, irrespective of temperature. In contrast, a moderately virulent strain SL1944 (race 1, biovar 4) showed the remarkable difference in disease progress on some resistant lines dependent on temperature. Moneymaker and Bonny Best were susceptible to SL1944 at all tested conditions with different temperature. However, tomato lines, such as Hawaii 7998, Hawaii 7996, Bblocking which were previously known as highly tolerant lines, were severely infected by SL1944 at relatively higher temperature ($35^{\circ}C$ for 14 hr light and $28^{\circ}C$ for 10 hr dark cycle). The disease progress at high temperature was much faster than those at low temprature on the same tomato line and those on Moneymaker and Bonny Best at the same high temprature. This result suggested that R. solanacearum strains isolated in Korea were highly virulent to bacterial wilt resistant tomato lines and some strains may cause severe infection on those plants at higher temperature.

• The Korean Journal of Pesticide Science
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• v.13 no.3
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• pp.185-189
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• 2009

A monoterpenoid compound, benzylideneacetone (BZA), is a metabolite of an entomopathogenic bacterium, Xenorhabdus nematophila. Its primary biological activity is an inhibitor of phospholipase $A_2$, which catalyzes the committed step of biosynthesis of various eicosanoids that are critically important to mediate insect immune responses. When BZA was applied to two-spotted spider mite, Tetranychus urticae, it exhibited a dose-dependent mortality in leaf-disc assay. Subsequently BZA was tested against T. urticae infesting apples in a field orchard, in which it showed a significant control efficacy, which was not statistically different with that of a commercial acaricide. BZA also had significant antibacterial activities against three species of plant pathogenic bacteria when it was added to the bacterial cultures, in which it showed the highest inhibitory activity against a bacterial wilt-causing pathogen, Ralstonia solanacearum. The bacterial pathogen caused significant disease symptom to young potato plants. However, BZA significantly suppressed the disease occurrence. This study suggests that BZA can be used to develop a novel crop protectant to control mite and bacterial pathogen.

• Research in Plant Disease
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• v.15 no.3
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• pp.198-201
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• 2009

Bacterial wilts, caused by Ralstonia solanacearum, is a very destructive disease to tomato plants (Solanum lycopersicum) in Korea. Selection of resistant cultivar is the best way to prevent or reduce the occurrence of this disease. Thirty-nine tomato cultivars, twenty-one cherry tomato cultivars and thirteen rootstock tomato cultivars were inoculated with Ralstonia solanacearum, to evaluate tomato cultivars for resistance against bacterial wilts. Thirty-seven cultivars were highly susceptible to bacterial wilts and 61-100% of their whole tissue became wilted within 10 days after inoculation. Twenty-four cultivars showed moderate resistance and twelve were resistant to bacterial wilts. In an evaluation of 73 major commercial cultivars, 'Lilyance', 'TP-7', 'Choice', 'Dadaki', 'Akiko', 'Redstar', 'Match', 'B-blocking', 'Magnet', 'Support', 'Friend' and 'Special' were found to have a high level of resistance to bacterial wilts of tomatoes.

• Research in Plant Disease
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• v.20 no.4
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• pp.253-258
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• 2014

This study was conducted to evaluate tomato plant resistance against bacterial wilt by Ralstonia solanacearum using tomato cultivars or tomato breeding lines maintained in RDA-Genebank of Rural Development Administration and to select resistant tomato lines for breeding purpose. We evaluated the disease responses of a total of 13 cultivars and 39 breeding lines from RDA-Genebank using R. solanacearum SL341 strain, which is a representative strain in Korea. Tomato cultivar Hawaii 7996 and Moneymaker were used as a resistant control plant and a susceptible control plant, respectively. A total of 32 cultivars were susceptible and 10 cultivars showed various disease response suggesting resistant phenotype segregation in the lines. Five commercial cultivars and 5 breeding lines exhibited strong resistance to bacterial wilt by the SL341 strain. These 5 breeding lines might be used for further study of plant defense response against bacterial wilt and cloning of the resistance gene from tomato plants. Ultimately, the selected lines could be used for tomato breeding to generate bacterial wilt resistant tomato plants.

• Current Research on Agriculture and Life Sciences
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• v.28
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• pp.39-46
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• 2010

Selection procedures for breeding lines resistant to both bacterial wilt caused by Ralstonia solanacearum and Phytophthora blight caused by P. capsici were executed to generations from $F_2$ and $BC_1F_1$ to $F_4$ and $BC_1F_3$ of crosses between a Phytophthora resistant breed, 'Chilbok No. 1' and bacterial wilt resistant accessions introduced from Vietnam during 2009 and 2010. The breeding populations or lines were tested for resistance to P. capsici and resistant plants were selected. The resistant selections were inoculated with R. solanacearum to discard susceptible plants. Resistance to P. capsici was conspicuously improved by selection from $F_2$ and $BC_1F_1$ and the final selections showed a similar level of resistance to P. capsici as a commercial Phytophthora resistant cultivar, Muhanjilju. A few $BC_1F_2$ selections were crossed to a cytoplasmic male sterile line, Chilbok-A, to identify their nuclear genotype interacting with male sterile cytoplasm. Majority of them was fixed to maintainer (Nrfrf) and only two resulted segregating into male sterile and male fertile plants indicating that the pollen parents were heterozygous in the fertility-restoring gene.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1998.06a
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• pp.168-169
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• 1998

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.313-319
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• 2006

Two hundred bacterial strains were isolated from the soil around healthy tomato plants in a polyvinyl house, where most of the other plants showed bacterial wilt symptoms. The strains were screened in vitro for their antibacterial activity. Among them, a strain, KPB3 showed strong bactericidal activity against bacterial wilt pathogen, Ralstonia solanacearum. The strain KPB3 was identified using physiological and biochemical tests, and 16S rRNA analyses. Based on these tests, the strain was found to be closer to genus Paenibacillus. To control the bacterial wilt caused by R. solanacearum, greenhouse experiments were conducted to determine the effectiveness of the Paenibacillus strain KPB3. Drench application of this strain ($4{\times}10^8$ CFU $mL^{-1}$) into the pots containing tomato plants, post-inoculated with the pathogen, R. solanacearum could drastically reduce the disease severity, compared to the non-treated plants. To evaluate effectiveness of this strain under field conditions, experiments were carried out in polyvinyl houses infested with R. solanacearum, during spring and autumn of the year 2006. It was observed that, during spring, bacterial wilt was more prevalent compared to the autumn. During spring, 50.9% disease incidences occurred in non-treated controls, while, Paenibacillus strain KPB3 treated plants showed 24.6% disease incidences. Similarly, during autumn, around 17.2% plants were infected with bacterial wilt in non- treated polyvinyl houses, compared to the Paenibacillus strain KPB3 treated plants, which showed 7.0% disease incidences. These results demonstrated that, Paenibacillus strain KPB3 is a potential biological control agent against bacterial wilt caused by R. solanacearum, effective under greenhouse as well as field conditions. This is the first report showing biocontrol of R. solanacearum using a Paenibacillus spp. under field conditions.

• Research in Plant Disease
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• v.23 no.4
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• pp.334-347
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• 2017

Bacterial wilt caused by Ralstonia solanacearum is an important disease in cultivation of chili pepper, causing plant death and significant yield losses. Cultivation of disease-resistant varieties is the most suitable measure to control bacterial wilt of chili pepper. To establish an efficient screening method for resistant chili pepper to R. solanacearum, six resistant or susceptible cultivars to the R. solanacearum were selected and the development of bacterial wilt on the cultivars according to several conditions was investigated. Drenching bacterial suspension into the cut roots using a scalpel was more simple and effective to distinguish resistant and susceptible cultivars than inoculation methods of root-dipping or soil-drenching without wounding. A resistant pepper, 'MC4' to R. solanacearum showed high resistance under the developed conditions which were 21- to 28-day-old pepper inoculated with $1{\times}10^8cfu/ml$ of bacterial suspension. On the other hands, the susceptible cultivars represented high disease severity under the conditions. These results indicated that we developed an efficient method to evaluate resistance of chili pepper cultivars against bacterial wilt. In addition, we successfully evaluated resistance degree of 140 commercial chili pepper cultivars to R. solanacearum using the developed method.