• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.125-130
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• 2010

Dollar spot and brown patch disease are the most economically important disease for highly maintained turfgrass area such as golf courses. Previous researches indicated that various natural fertilizers are good nitrogen (N) sources and they may lead to turf disease suppression because disease suppression by natural N sources may be due to microbial activity increased. Increased microbial activities in soil reduce the activity of plant pathogen. The objective of this study was to evaluate efficacy of various N sources to suppress dollar spot and brown patch on creeping bentgrass. The seven N sources and fungicide combinations were investigated for turf disease suppression. $Emerald^{TM}$ and $ProStar^{TM}$ were applied for the applications of fungicide combination. No differences were found on turf quality among N source treatments. However, there was significant difference on turf quality between fungicide combination and fungicide combination plus urea. Overall, N source had no significant effects on suppression of dollar spot and brown patch. Although there were a few differences among N source treatments, fungicide treatments were needed for turf disease suppression for highly maintained turfgrass area such as golf courses.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.296-300
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• 2005

Among the root colonizing and plant growth promoting bacteria isolated from the bacterial wilt suppressive soil, five strains were detected to produce siderophores by CAS agar assay. The most effective isolate, TS3-7 strain induced significant suppression of bacterial wilt disease in tomato and pepper plants. Seed treatment followed by soil drench application with this strain resulted in over 80% reduction of bacterial wilt disease compared with the control. Significant disease suppression by TS3-7 strain was related to the production of siderophore. Besides iron competition, induction of resistance of the host plant with siderophore was suggested to be another mode of action that suppress bacterial wilt, based on the lack of direct antibiosis against pathogen in vitro. According to Bergey's Manual of Systemic Bacteriology and 16S rDNA sequence data, TS3-7 stain was identified as Pseudomonas sp. TS3-7.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.136-143
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• 2013

Microbial communities that are associated with plant roots are highly diverse and harbor tens of thousands of species. This so-called microbiome controls plant health through several mechanisms including the suppression of infectious diseases, which is especially prominent in disease suppressive soils. The mechanisms implicated in disease suppression include competition for nutrients, antibiosis, and induced systemic resistance (ISR). For many biological control agents ISR has been recognized as the mechanism that at least partly explains disease suppression. Implications of ISR on recruitment and functioning of the rhizosphere microbiome are discussed.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.216-227
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• 2016

Biological control agents (BCAs) from different microbial taxa are increasingly used to control bacterial wilt caused by Ralstonia solanacearum. However, a quantitative research synthesis has not been conducted on the role of BCAs in disease suppression. Therefore, the present study aimed to meta-analyze the impacts of BCAs on both Ralstonia wilt disease suppression and plant (host) growth promotion. The analysis showed that the extent of disease suppression by BCAs varied widely among studies, with effect size (log response ratio) ranging from -2.84 to 2.13. The disease incidence and severity were significantly decreased on average by 53.7% and 49.3%, respectively. BCAs inoculation also significantly increased fresh and dry weight by 34.4% and 36.1%, respectively on average. Also, BCAs inoculation significantly increased plant yield by 66%. Mean effect sizes for genus Pseudomonas sp. as BCAs were higher than for genus Bacillus spp. Among antagonists tested, P. fluorescens, P. putida, B. cereus, B. subtilis and B. amyloliquefaciens were found to be more effective in general for disease reduction. Across studies, highest disease control was found for P. fluorescens, annual plants, co-inoculation with more than one BCA, soil drench and greenhouse condition were found to be essential in understanding plant responses to R. solanacearum. Our results suggest that more efforts should be devoted to harnessing the potential beneficial effects of these antagonists, not just for plant growth promoting traits but also in mode of applications, BCAs formulations and their field studies should be considered in the future for R. solanacearum wilt disease suppression.

• The Plant Pathology Journal
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• v.26 no.3
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• pp.231-237
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• 2010

The heat-inactivated (at $121^{\circ}C$ for 20 min) conidial suspension of Bipolaris cactivora (HICS) was evaluated for the control of Bipolaris stem rot of cactus caused by B. cactivora. Severe rot symptoms were developed on the cactus stem discs inoculated with B. cactivora from 5 days after inoculation. However, only small brownish spots developed on the stem discs treated with HICS 2 days prior to the pathogen inoculation. HICS also reduced symptom development on cactus stem discs inoculated with other fungal pathogens such as Alternaria alternata, Colletotrichum gloeosporioides, and Fusarium oxysporum, suggesting its disease-inhibitory efficacy may not be pathogen-specific. HICS significantly reduced severities of the stem rot disease on several cactus species including Hylocereus trigonus, Cereus peruvianus, Chamaecereus silvestrii and Gymnocalycium mianovichii, but not on Cereus tetragonus. Extensive wound periderms were formed in the stem tissues of inoculation and/or wounding sites on C. peruvianus treated with HICS alone or prior to the pathogen inoculation, but not on C. tetragonus, indicating the structural modifications may be related to the mechanism of disease suppression by HICS. HICS also reduced the disease development on the grafted cactus (H. trigonus stock and G. mianovichii scion) with the control efficacy nearly equivalent to the application of a commercial fungicide. All of these results suggest HICS can be used as an environmental-friendly agent for the control of the cactus stem disease.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.364-368
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• 2006

Survival of biocontrol agents and their effective colonization of rhizhosphere are the essential components for successful disease suppression. The effects of hydrogel supplement on bacterial survival and disease control were evaluated in pot and in the field. Addition of 2% hydrogel material to potting soil resulted in significant enhancement of colonization of biocontrol agent Serratia plymuthica A21-4 both in soil and rhizosphere of pepper plants. Rhizosphere colonization of S. plymuthica A21-4 retrieved from 40 days old pepper seedlings indicated 100 times higher bacterial population in hydrogel treated soil than in ordinary pot soil. The pepper plants sown in hydrogelated potting soil showed higher seed germination rate and the better growth of pepper plant than those in ordinary commercial pot soil. Although the suppression of Phytophthora capsid density in the potting soil by treatment of biocontrol agent A21-4 was not significantly different between in hydrogelated soil and ordinary potting soil, the suppression of Phytophthora blight between two treatments was significantly different. A21-4 treatment in hydrogelated potting soil was completely disease-free while same treatment in ordinary potting soil revealed 36% disease incidence. Our field study under natural disease occurrence also showed significantly less disease incidence(12.3%) in the A21-4 treatment in the hydrogelated soil compared to other treatments. Yield promotion of pepper by the A21-4 treatment in the hydrogelated potting soil was also recognized. Our results indicated that hydrogel amendment with biocontrol agent in pot soil would be a good alternative to protect pepper seedlings and increase plant yield.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.278-282
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• 2006

Bacillus vallismortis EXTN-1, a biocontrol agent in cucumber, tomato and potato was tested in rice pathosystem against rice fungal pathogens viz. Magnaporthe grisea, Rhizoctonia solani and Cochliobolus miyabeanus. Apart from increasing the yield in the bacterized plants (11.6-12.6% over control), the study showed that EXTN1 is effective in bringing about disease suppression against all the tested fungal pathogens. EXTN-l treatment resulted in 52.11% reduction in rice blast, 83.02% reduction in sheath blight and 11.54% decrease in brown spot symptoms. As the strain is proven as an inducer for systemic resistance based on PR gene expression in Arabidopsis and tobacco models, it is supposed that a similar mechanism works in rice, bringing about disease suppression. The strain could be used as a potent biocontrol and growth-promoting agent in rice cropping system.

• IMMUNE NETWORK
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• v.2 no.2
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• pp.65-71
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• 2002

The immunological mechanism of the responses to ultraviolet (UV) B radiation in mouse models were investigated by the suppression of contact hypersensitivity (CHS) and delayed type hypersensitivity (DTH), and susceptibility to infection. However, there are some differences in immune suppression according to the different models as well as the irradiation protocols. Therefore, this review focused on the differences in the suppressive effects on CHS and DTH, and susceptibility to infection in relation to the different in vivo models. Recent advances in cytokine knockout mice experiments have the reexamination of the role of the critical cytokines in UVB-induced immune suppression, which was investigated previously by blocking antibodies. The characteristics of the suppressor cells responsible for UVB-induced tolerance were determined. The subcellular mechanism of UVB-induced immune suppression was also explained by the induction of apoptotic cells through the Fas and Fas-ligand interaction. The phagocytosis of the apoptotic cells is believed to induce the production of the immune suppressive cytokine like interleukin-10 by macrophages. Therefore, the therapeutic UVB response to a skin disease, such as psoriasis, by the depletion of infiltrating T cells could be considered in the extension line of apoptosis and immune suppression.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.606-611
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• 1998

An antagonistic bacterium, Pseudomonas flurorescens MC07 inhibited the mycelial growth of Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici in on potato dextrose agan (PDA) and other media. The strain MC07 conlonizes various plant roots and possesses antifungal activity. To determine the role of antifungal activity of the bacterium in disease suppression, a mutant Okm3-4 which lost its activity was isolated after screening 2,500 colonies generated by Omegon-Km insertions. The mutant Okm3-4 showed diminished growth inhibition of R. solani, P. ultimum, F. oxysporum, and Ph. capsici in vitro and had reduced suppressive effects on sesame damping.-off compared to the parental strain. In soils, accumulation of the pathogens by continuous cropping, 90% of sesame plants were killed by natural infection of damping-off whereas, only 29% of plants grown from seeds treated with MC07 were killed. On the other hand, 85% of plants died when sesame seeds were treated with the Okm3-4 cells. This indicated that antifungal activity of MC07 in vitro is directly responsible for the suppression of damping-off disease. Emergence rates of sesame seeds in pots containing diseased soil were 33%. However, MC07 treatments on seeds significantly improved emergence rates, which has similar effects of Benomyl treatment. The mutant Okm3-4 exhibited 53% of emergence rate. This indicated that antifungal activity of MC07 also affects the emergence rate of sesame seeds.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.16 no.3
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• pp.171-177
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• 2013

Purpose: This study was aimed to evaluate the frequency and course of adverse events associated with azathioprine treatment in Korean pediatric patients with inflammatory bowel disease. Methods: Total of 174 pediatric patients (age range, 1 to 19 years) with inflammatory bowel disease who received azathioprine in order to maintain remission at Samsung Medical Center (Seoul, Korea) from January 2002 through December 2012 were included in this study. Medical records of these subjects were retrospectively reviewed regarding the development of adverse events associated with azathioprine treatment. Results: Ninety-eight patients (56.3%) of 174 patients experienced 136 episodes of adverse events, requiring dose reduction in 31 patients (17.8%), and discontinuation in 18 patients (10.3%). The mean dose of azathioprine that had been initially administered was $1.32{\pm}0.42$ mg/kg/day. Among the adverse reactions, bone marrow suppression developed in 47 patients (27.0%), requiring dose reduction in 22 patients (12.6%) and discontinuation in 8 patients (4.6%). Other adverse events that occurred were gastrointestinal disturbance (15.5%), hair loss (12.1%), pancreatitis (7.5%), arthralgia (6.9%), hepatotoxicity (2.9%), skin rash/allergic reactions (2.9%), headache/dizziness (2.3%), sepsis (0.6%), and oral mucositis (0.6%). Conclusion: Bone marrow suppression, especially leukopenia was most commonly associated with azathioprine treatment in Korean pediatric inflammatory bowel disease patients. Close observation for possible adverse events is required in this population with inflammatory bowel diseases who are under treatment with azathioprine.