• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.422-428
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• 2005

In vivo antifungal activity of 44 fungicides consisting of 3 clubroot fungicides, 7 Oomycetes fungicides, 7 botriticides, 7 blasticides, 9 sterol biosynthesis inhibitors, and 11 broad spectrum fungicides were investigated against Plamodiophora brassicae, the causal agent of clubroot disease in Chinese cabbage. When fluazinam, flusulfamide and cyazofamid, commercial fungicide to control clubroot of Chinese cabbage in Korea, were applied to infested soil, club formations by P. brassicae were strongly inhibited at pot (35 $cm^2$) per 0.63 mg. Ethaboxam and cymoxanil, Oomycetes fungicides, completely controlled Chinese cabbage clubroot at 5 mg/pot, but cymoxanil represented sever phytotoxicity. Besides, dichlofluanid and procymidone of botriticides effectively controlled the development of Chinese cabbage clubroot at 2.5 mg/pot. Chlorothalonil, quintozene and trichlamide, broad spectrum fungicides, showed disease-control efficacy of 85%, 100% and 100% at 2.5 mg/pot, respectively. Most of sterol biosynthesis inhibitors displayed the strong antifungal activity against P. brassicae on cabbage seedlings and plant growth -retarding activity. From these results, 7 fungicides were selected and further tested in vivo antifungal activity against P. brassicae in glasshouse. Among them, ethaboxam showed the most antifungal activity against P. brassicae on cabbage seedlings, followed by fenarimol, procymidone, nuarimol and chlorothalonil.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.37-37
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• 2015

Kimchi cabbage (Chinese cabbage), radish and Cabbage are major Brassicaceae vegetables in Korea. Especially, we can easily develop whole plant from one microspore in Kimchi cabbage. To develop clubroot resistant doubled-haploid (DH) inbred lines, we pollinated a clubroot resistant turnip of 'IT 033820' with a Kimchi cabbage (Chinese cabbage) inbred of 'BP 079'. More than 85 DH inbred lines were developed from this combination. We screened about 400 materials including these DH inbred lines, commercial cultivars and breeding materials during 3 years using hydroponic system after inoculating single spore isolation race 4(SSI-04) inoculate. One inbred line derived from this combination selected as clubroot resistant and registered as 'Wonkyo20036ho'. We inoculated 26 DH inbred lines derived from 'Zoong-baek 2ho' using SSI-4, the percent of resistant plants varied from 0 to 83%. However the horticultural traits of highly resistant DH inbred line was poor. Thus we selected one DH line showing 77% resistant with yellow inner leaf and maid good head, was registered as 'Wonkyo20034ho'. Another DH inbred line derived from Korean variety of 'Wol-dong' showing 86% resistant was registered as 'Wonkyo20037ho'. Other DH inbred lines were derived from Chinese cultivar of 'Choon-hi-go-hang-wang' and 'Hwang-shim-zo48' showed 80 and 71% resistant, respectively, was also selected for registration. Even though DH inbred lines derived from turnip showed highly resistant to SSI-04 and provincial inoculate, they showed poor characteristics in horticultural traits. However, commercial seed companies showed interesting for adapting these DH inbred lines in commercial breeding.

• Research in Plant Disease
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• v.9 no.2
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• pp.57-63
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• 2003

Clubroot disease of curcifer crops caused by Plasmodiophora brassicae had been first reported in 1928 in Korea, and maintained mild occurrence until 1980s. Since 1990s the disease has become severe in alpine areas of Kyonggi and Kangwon, gradually spread to plain fields throughout the country, and remains as the great-est limiting factor for its production. Researches on the disease has begun in late 1990s after experiencing severe epidemics. Survey of occurrence and etiological studies have been carried out, particularly, on the pathogen physiology, race identification, quantification of soil pathogen population, and host spectrum of the pathogen. Ecology of gall formation and its decay, yield loss assessment associated with time of infection, and relationships between crop rotation and the disease incidence was also studied during late 1990s. In studies of its control, more than 200 crucifer cultivars were evaluated for their resistance to the disease. Lime applica-tion to field soil was also attempted to reduce the disease incidence. Resistant radish and welsh onion were recommended as rotation crops with crucifers after 3-year field experiments. However, so for, most studies on clubroot disease in Korea have been focused on chemical control. Two fungicides, fluazinam and flusulfamide, were selected and extensively studied on their application technologies and combination effects with lime application or other soil treatment. To develop environmentally-friendly control methods, solar-disinfection of soil, phosphoric acid as a nontoxic compound, and root-parasiting endophytes as biocontrol agents were examined for their effects on the disease in fields. In the future, more researches are needed to be done on development of resistant varieties effective to several races of the pathogen, establishment of economically-sound crop rotation system, and improvement of soil-disinfection technique applicable to Korean field condi-tion, and development of methodology of pretreatment of fungicides onto seeds and seedbeds.

• Research in Plant Disease
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• v.6 no.1
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• pp.39-42
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• 2000

This study was conducted to improvement of control efficiency on clubroot disease. To improve the control efficiency on clubroot disease of chinese cabbage by chemical persistent effect, Flusulfamide DP was examined with soil mixed treatment. When Flusulfamide DP was applied, the more application times, the higher control value. The control value and marketable yield per 10a of the untreated cultivation plot after two application of Flusulfamide DP were 53.9%, 4,822kg, respectively. However, based on marketability and marketable yield, untreated cultivation plot after two application of Flusulfamide DP has been thought as economic application times compared to three times application. On the other hand, the combination of soil mixing and bed soil mixing treatment Flusulfamide DP was more effective than each treatment. The control value and marketable yield of the combination treatment was 73.3∼88.9%, 5,633∼5,770kg, those of soil mixing 66.7∼70.0%, 2,847∼3,167kg, respectively.

• Research in Plant Disease
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• v.12 no.3
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• pp.278-283
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• 2006

The effect of calcium cyanamide($CaCN_2$) on suppression of clubroot of Chinese cabbage was evaluated in the fields infested with Plasmodiophora brassicae at National Institute of Highland Agriculture, Pyeongchang, Korea, from 2002 to 2003. Calcium cyanamide was found to be more effective in reducing disease severity than flusulfamide dust powder. The optimal dosage of calcium cyanamide for control of clubroot of Chinese cabbage was 61 kg/10a. When calcium cyanamide was incorporated into soil at 5, 10, 15 and 20 days before planting(DBP), maximum disease suppression was obtained in the plot with calcium cyanamide, applied 5DBP. The fertilizer property of calcium cyanamide as a nitrogen fertilizer was also investigated by comparing with urea on cv. CR Gangta, a resistant variety of Chinese cabbage. The nitrogen uptake in calcium cyanamide treatment(17.6 kg/10a), was not significantly different from that of urea(17.8 kg/10a). These results indicated that calcium cyanamide could be used as a soil disinfectant as well as a nitrogen fertilizer.

• The Plant Pathology Journal
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• v.34 no.6
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• pp.506-513
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• 2018

Clubroot is one of the most economically important diseases of the Brassicaceae family. Clubroot disease is caused by the obligate parasite Plasmodiophora brassicae, which is difficult to study because it is nonculturable in the laboratory and its races are genetically variable worldwide. In Korea, there are at least five races that belongs to four pathotype groups. A recent study conducted in Korea attempted to develop molecular markers based on ribosomal DNA polymorphism to detect P. brassicae isolates, but none of those markers was either race-specific or pathotype-specific. Our current study aimed to develop race- and isolate-specific markers by exploiting genomic sequence variations. A total of 119 markers were developed based on unique variation exists in genomic sequences of each of the races. Only 12 markers were able to detect P. brassicae strains of each isolate or race. Ycheon14 markers was specific to isolates of race 2, Yeoncheon and Hoengseong. Ycheon9 and Ycheon10 markers were specific to Yeoncheon isolate (race 2, pathotype 3), ZJ1-3, ZJ1-4 and ZJ1-5 markers were specific to Haenam2 (race 4) isolate, ZJ1-35, ZJ1-40, ZJ1-41 and ZJ1-49 markers were specific to Hoengseong isolate and ZJ1-56 and ZJ1-64 markers were specific to Pyeongchang isolate (race 4, pathotype 3). The PCR-based sequence characterized amplified region (SCAR) markers developed in this study are able to detect five Korean isolates of P. brassicae. These markers can be utilized in identifying four Korean P. brassicae isolates from different regions. Additional effort is required to develop race- and isolate-specific markers for the remaining Korean isolates.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.29-29
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• 2015

Clubroot disease is caused by the soil-born obligate plant pathogen Plasmodiophora brassicae. This pathogen can infect all cruciferous vegetables and oil crops, including Brassica rapa, B. oleracea, B. napus, and other Brassica species. Clubroot disease is now considered to be a major problem in Chinese cabbage production in China, Korea, and Japan. We collected several hundreds of P. brassicae infected galls from Korea, and isolated the single spore from the collection. For establishment of novel isolation, and mass-propagation methods for singe spore isolates of P. brassicae pathogen, we developed new filtration method using both cellulose nitrate filter and syringe filter. Accurate detection of P. brassicae pathogen in the field was done by using real-time PCR in the potential infested soil. When we tested the different pathogenicity on commercial Chinese cabbage varieties, P. brassicae from collected galls showed various morphological patterns about clubroot symptom on roots. To date, 8 CR loci have been identified in the B. rapa genome using the quantitative trait loci (QTL) mapping approach, with different resistant sources and isolates. We are trying to develop the molecular marker systems for detect all 8 CR resistant genes. Especially for the study on the interaction between pathogens and CR loci which are not well understood until now, genome wide association studies are doing using the sequenced inbred lines of Chinese cabbage to detect the novel CR genes.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.38-38
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• 2015

Throughout the world, clubroot disease is one of the most damaging diseases affecting Brassica oleracea. In order to perform QTL analysis of CR (clubroot resistance) loci in B. oleracea, we constructed a map, and analyzed CR-QTLs using the mean phenotypes of F3 progenies from the cross of a resistant double-haploid cabbage line (Anju) with a susceptible double-haploid broccoli line (GC). We identified one major QTL, pb-Bo(Anju)1 in C2 from Anju and four minor QTLs; pb-Bo(GC)1 in O5 from GC, pb-Bo(Anju)2, -3, -4 in C2, C3, and C7 from Anju, respectively. Additionally, we found that the accumulation of Pb-Bo(Anju)1 allele and the minor CR-QTLs is essential for resistance against various six isolates. Our finding markers closely linked to the CR-QTLs will help marker-assisted selection for CR. At present, we are undergoing toward map-based cloning for Pb-Bo(Anju)1 gene. The preliminary experiment delimited Pb-Bo(Anju)1 locus, encompassing among 450kB.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.42-42
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• 2015

Plasmodiophora brassicae, the causal agent of clubroot disease, does the most serious damage to the Brassica crops. The limited control approaches make that the identification of clubroot resistance (CR) is more important for developing CR cultivars of the Brassica crops. So far, 8 CR loci were mapped. However, the variation of P. brassicae leads to the rapid erosion of its resistance. To identify novel CR genes, we employed three mapping population, derived from crosses between Chinese cabbage and turnip inbred lines ($59-1{\times}ECD04$ and $BJN3-1{\times}Siloga$) or between Chinese cabbage inbred lines ($BJN3-1{\times}85-I-II$), to perform QTL analysis. Totally, 8 CR loci were indentified and showed race-specific resistance. Physical mapping of these 8 loci suggested that 4 were located previously mapped position, indicating they might be the same allele or different alleles of the same genes. Other 4 loci were found to be novel. Further, CR near isogenic line carrying each CR locus was developed based on the marker assisted selection. Verification of these CR loci was underway. Identification of these novel CR genes would facilitate to breed broad-spectrum and durable CR cultivars of B. rapa by pyramiding strategies.

• Journal of Plant Biotechnology
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• v.42 no.4
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• pp.350-355
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• 2015

Clubroot disease is one of the most wide-spread and devastating diseases in the cultivation of Chinese cabbage. To develop a protein marker for resistance to clubroot disease in Chinese cabbage, a comparative proteome analysis was performed between a sensitive line, 94SK, and a resistant line, CR Shinki DH. Three proteins of two fold or higher accumulation that are specific to each line were found 3 days after innoculation of the Plasmodiphora brassicae. They are glutamine synthetase, malate dehydrogenase/oxidoreductase and fructose-bisphosphate aldolase in the 94SK and actin, phosphoglycerate kinase, and Cu/Zn superoxide dismutase in the CR Shinki line. From the comparison of the synthesized proteins in the 94SK and the CR Shinki, CR Shinki was found to produce more ATP-binding protein for the ABC transporter while 94SK showed a higher level of pathogenesis-related protein 1 production. All of these proteomic variations may lead to the development of molecular markers to accelerate the breeding process.