• The Plant Pathology Journal
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• v.38 no.2
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• pp.146-158
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• 2022

Changes in physiological and biochemical patterns in lucerne plants caused by the presence of 'Candidatus Phytoplasma australasia', which is one of the significant pathogens causing yield losses in lucerne plants, were investigated. Significant differences were evident in total chlorophyll, chlorophyll a, chlorophyll b, and protein amounts between 'Ca. Phytoplasma australasia'-positive and negative lucerne plants. Stress-related metabolites such as phenol, malondialdehyde, and proline accumulations in 'Ca. Phytoplasma australasia'-positive plants were remarkably higher than those of phytoplasma-negative plants. As a response to disease attack, phytoplasma-positive plants exhibited higher antioxidant enzymes (peroxidase and catalase) and nonenzymatic metabolite responses such as jasmonic and salicylic acids. We state that partial disease responses were revealed for the first time to breed resistant lucerne lines infected by 'Ca. Phytoplasma australasia'.

• The Plant Pathology Journal
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• v.40 no.3
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• pp.299-309
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• 2024

The rice blast disease, caused by the fungal pathogen, Magnaporthe oryzae (syn. Pyricularia oryzae), poses a significant threat to the global rice production. Understanding how this disease impacts the plant's microbial communities is crucial for gaining insights into host-pathogen interactions. In this study, we investigated the changes in communities of bacterial and fungal endophytes inhabiting different compartments in healthy and diseased plants. We found that both alpha and beta diversities of endophytic communities do not change significantly by the pathogen infection. Rather, the type of plant compartment appeared to be the main driver of endophytic community structures. Although the overall structure seemed to be consistent between healthy and diseased plants, our analysis of differentially abundant taxa revealed the specific bacterial and fungal operational taxonomic units that exhibited enrichment in the root and leaf compartments of infected plants. These findings suggest that endophyte communities are robust to the changes at the early stage of pathogen infection, and that some of endophytes enriched in infected plants might have roles in the defense against the pathogen.

• Plant Disease and Agriculture
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• v.5 no.1
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• pp.61-63
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• 1999

Bacterial soft rot was observed on radish grown in Hongcheon, Kanwon-Do, Korea. The soft rot symptoms began as small water-soaked lesions. The water-soaked lesions enlarged rapidly in roots and produced a foul odor. When roots were affected in the field, the shoots also became infected and watery, causing infected plants to wilt, disorganize, and die. The causal organism was isolated from the lesions, and the identified as Erwinia chrysanthemi based on the morphological, physiological and biochemical characteristics. E. chrysanthemi is first described bacterium which causes bacterial soft rot on radish in Korea.

• Journal of Plant Biology
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• v.16 no.3_4
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• pp.35-39
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• 1973

This investigation was conducted to study the effect of soybean mosaic virus (SMV) on various parameters of nodule formation at different stage of soybean plants. Differences in nodule formation were marked between soybean varieties tested, but nodules were small within soybean varieties infected with SMV. SMV-infection on soybeans were greatly reduced the number, size and weight of nodules, and the earlier the infection of SMV, the greater the reduction of nodules. Maximum reduction(83%) of nodules observed when "Kumkang-Daerip" soybeans were inoculated 2 weeks after seeding, but none occurred 8 weeks or later. Prominent decreases in number of nodules often resulted in an increase in nodu'e sizes in SMV-infected soybean plants.an plants.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.131.2-132
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• 2003

White rot on garlic caused by Sclerotium cepivorum firstly occurred at Goheoung, Jeonnam in 1998. Thereafter, the disease rapidly spread throughout the country except Gangwon and became a major limiting factor for the cultivation of various Allium species such as garlic, onion, and welsh onion. The disease that has not been reported on a wild garlic(Allium monanthum) previously occurred severely at Seosan, Choongnam in 2003. Among cultivation areas in the region, 10.7％ were infected by the disease and the ratio of diseased plant reached up to 55.0％ in some heavily infected fields. Two species of Sclerotium were consistently isolated from infected samples and identified as S. cepivorum or another Sclerotium sp. Averaged size of sclerotium of the former was 455.0x562.2 urn, while the later was 374.4${\times}$347.2$\mu\textrm{m}$. Patogenicity to Allium species and mycological characteristics such as sclerotium size, growth temperature, and microconidia of the fungi were similar to those reported on other Allium species previously. Consequently, the wild garlic is a newly reported host of the two pathogenic fungi in Korea.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.115-120
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• 2002

Xanthomonas axonopodis pv. glycines, the causal agent of bacterial pustule of soybean, induces hypersensitive response (HR) in a non-host plant, hot pepper (Capsicum annuum). A wild-type strain (8ra) and its non-patho-genic mutant (8-13) of X. axonopodis pv. glycines were inoculated into the pepper leaf tissues and their subcellular responses to the bacterial infections were examined by electron microscopy. Intrastructural changes related to HR were found in the leaf tissues infected with 8ra from 8 h after inoculation, characterized by separation of plasmalemma from the cell wall, formation of small vacuoles and vesicles, formation of cell wall apposition, and cellular necrosis. No such responses were observed in the tissues infected with the mutant. In 8ra, the bacterial cells were attached to the cell walls, with the cell wall material dissolved into and appearing to encapsulate the bacterial cells. The bacterial cells later became entirely embedded in the cell wall material. On the other hand, in 8-13, the bacterial cells were usually not attached tightly to the plant cell wall, and no or poor encapsulation of the bacteria by the wall material occurred, although these were encircled by rather loose wall materials at the later stages.

• The Plant Pathology Journal
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• v.17 no.1
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• pp.62-66
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• 2001

Detection of Xanthomonas axonopodis pv. citri (Xac) on citrus fruits for exporting is usually made by bacteriophage test (BPT) to demonstrate the pathogen-free status. BPT has rather time-consuming and complicate procedures for dealing with massive samples to be inspected. In this study, enzyme-linked immunosorbent assay (ELISA) was applied to detect Xac on fruits, and compared with BPT. In ELISA, positive reactions occurred in the bacterial densities of $3\times10^5$ cells/ml or more. To detect the bacterial infection on citrus fruits with a density of lower than $3\times10^5$ cells/ml, the bacterial suspensions were mixed with fruit rinse water and incubated in broth medium. Ordinary peptone sucrose broth (PSB) was not a proper medium for increasing Xac density specifically enough to be detect by ELISA. On the other hand, modified PSB (MPSP) amended with Fe-EDTA (0.25 g/$\ell$) and 2.5% potato-dextrose broth sufficed to differentiate uninfected and infected citrus fruits by ELISA after 24 h incubation of the fruit rinse water. Using various citrus samples from infected and uninfected fields, efficiencies in detecting Xac on fruits were compared between ELISA and BPT. For infected fruits samples, ELISA detected Xac by 100%, while BPT by about 44%, indicating that the detection efficiency was improved by 23.5% by ELISA, compared to BPT. In addition, ELISA has simpler procedures for testing and is less time-consuming than BPT, suggesting that ELISA may be accurate and simple method to detect Xac on citrus fruits.

• The Korean Journal of Mycology
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• v.12 no.2
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• pp.65-73
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• 1984

Strain IV caused highest reduction of germination and caused abnormal elongation of all part of the plant which finally died. Milyang 23 and Nampungbyeo formed mesocotyl. Samnambyeo and Jinjubyeo did not formed mesocotyl on the soil surface in nursery boxes when they were planted on soil infested with each strain of F. moniliforme. Infected seedlings with mesocotyl recovered after transplanting in the the field. The most frequency of Strain IV was isolated from infected rices and this strain was isolated from all part of rice. When rice seedling infected with Strain IV were transplanted in paddy field, most of rice showed Bakanae symptom. Ear emergence of rice was more delayed when seedlings infected with Strain IV were transplanted than that of healthy plant. Number of panicle per hill and grain yield from rice when infected rice seedling by Strain IV were transplanted were more decreased than that of the healthy plant in paddy field.

• Korean journal of applied entomology
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• v.21 no.1 s.50
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• pp.23-26
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• 1982

The present study was carried out to investigate the change of peroxidase activity of soybean seed infected with Cerrospora kikurhii. The protein content, polyphenol oxidase activity and peroxidase isozyme pattern in health and infected soybean seed were also compared. 1. The peroxidase activity was substantially higher in the infected soybean seeds than that in the healthy seeds either cracked or not. No significant differences in protein content were recognized among the seeds tested. 2. No significant differences in peroxidase activities and protein contents were notified between healthy and infected seeds from the measurements on each parts of dissected seeds, cotyledon and seedcoat, however the peroxidase activity in the seed coat of the stained seed was 2.5 times to healthy seed. 3. The activities of polyphenel oxidase were undectable in both healthy and diseased seeds. 4. The electrophoretic Patterns of the Peroridase isozyme were the same between healthy and in footed seed. 5. Therefore, the increase of peroxidase activity in infected soybean seedcoat was mainly due to the biochemical reaction against the pathogen.

• Korean journal of applied entomology
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• v.21 no.4 s.53
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• pp.222-226
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• 1982

Changes in levels of phenolic compounds such as total phenols, flavonols and anthocyanins in Macrophoma-infected apples were studied at various developmental stages of apple fruits. The amounts of total phenols in apple fruit flesh and peel drastically decreased as apples became mature. Apple rot resulted in concentration of total phenols somewhat lower than those of healthy apple flesh. The decline in amount of total phenols was distinct in infected fruit flesh of the cultivar Fuji, which was more susceptible to Macrophoma sp. than the cultivar Miller. Higher amounts of total phenols were found in infected than in heathy fruit peel. In the case of the cultivar Miller, increased accumulation of total phenols was pronounced in infected peel. Apple rot resulted in concentrations of flavonols much higher than those of healthy apples. In particular, the drastically increased accumulation of flavonols was detected in infected peel at the first collection on 10 July, when the cultivars tested were completely resistant to Macrophoma sp. Production of anthocyanins was increased considerably by apple rot: anthocyanins in infected fruits of the cultivar Miller increased markedly as compared with their concentration from healthy fruits. These results suggest that the altered phenolic metabolism in apple fruits may be associated with the development of apple rot.