• Journal of fish pathology
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• v.22 no.2
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• pp.115-124
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• 2009

Photobacterium damselae subsp. damselae and 4 Vibrio spp, V. anguillarum, V. splendidus, V. harveyi and V. ordalii, were isolated from the diseased olive flounders, Paralichthys olivaceus. The pathogenicity of the isolates were compared to mortality, blood biochemical contents, such as alanineaminotransferase(ALT), aspatate aminotransferase(AST), and cortisol level, and non-specific immune responses, nitroblue tetrazolium (NBT) reduction of macrophages and lysozyme activities of serum. The mortalities and levels of ALT, AST and cortisol of fishes infected with P. damselae were higher than those of others but significantly low in non-specific immune responses, NBT and lysozyme activities. These results suggest that P. damsela might produce damselysin having high hemolytic and phospholipase activities, correlated with the pathogenicity. P. damsela could also make an obstruction of internal organs, following increasing in the level of ALT and AST, and depression in host immunity caused by induced high levels of cortisol.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.4
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• pp.591-601
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• 2012

Olive flounders, Paralichthys olivaceus, were intraperitoneally challenged with Edwardsiella tarda or Streptococcus iniae or both bacteria simultaneously. The pathogenicity was respectively compared with blood chemical using alanine aminotransferase (ALT), aspatate aminotransferase (AST), glucose and total protein, lysozyme activity, bacterial number of kidney and spleen, histopathological change, and cumulative mortality. The tested group of coinfection showed increased cumulative mortality, bacterial number of kidney and spleen, AST and histopathological change, but not in lysozyme activity compared with others. This study provides support for the conclusion that simultaneous infection with Edwardsiella tarda and Streptococcus iniae in a susceptible host results in higher pathogenicity, leading to the increment of bacterial number and the destruction of the internal organs.

• The Plant Pathology Journal
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• v.37 no.4
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• pp.365-374
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• 2021

White rot or stem rot caused by Sclerotinia sclerotiorum is one of the most destructive fungal diseases that have become a serious threat to the successful cultivation of oilseed Brassicas. The study was designed with an aim to investigate the association between the pathogenic aggressiveness and pathogenicity determinants of this pathogen specifically in Brassica for the first time. For this, a total of 58 isolates of S. sclerotiorum from different geographical regions were collected and purified. These isolates were inoculated on a Brassica juncea cv. RL-1359 and they exhibited high level of variation in their disease progression. The isolates were grouped and then 24 isolates were selected for the biochemical analysis of pathogenicity determinants. The isolates varied significantly with respect to their total organic acids, oxalic acid production and pectin methyl esterase and polygalacturonase activity. The oxalic acid production corresponded to the disease progression of the isolates; the isolates with higher oxalic acid production were the more aggressive ones and vice-versa. This is, in our knowledge, the first study to establish a correlation between oxalic acid production and pathogenic aggressiveness of S. sclerotiorum on B. juncea. However, the pectinases' enzyme activity did not follow the trend as of disease progression. These suggest an indispensable role of oxalic acid in pathogenicity of the fungus and the potential to be used as biochemical marker for preliminary assessment of pathogenic aggressiveness of various isolates before incorporating them in a breeding program.

• The Plant Pathology Journal
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• v.38 no.2
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• pp.90-101
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• 2022

Pathogenicity of eight Bacillus strains to seedlings of four cotton cultivars was evaluated under greenhouse conditions. Each of the tested cultivars was individually treated with powdered inoculum of each bacterial strain. Untreated seeds were planted as control treatments in autoclaved soil. Effects of the tested strains on levels and activities of some biochemical components of the infected seedlings were also assayed. The biochemical components included total soluble sugars, total soluble proteins, total free amino acids, peroxidase, polyphenol oxidase, phenols, and lipid peroxidation. ANOVA showed that Bacillus strain (B) was a very highly significant source of variation in damping-off and dry weight. Cotton cultivar (V) was a nonsignificant source of variation in damping-off while it was a significant source of variation in dry weight. B × V interaction was a significant source of variation in damping-off and a nonsignificant source of variation in dry weight. Bacillus strain was the most important source of variation as it accounted for 59.36 and 64.99% of the explained (model) variation in damping-off and dry weight, respectively. The lack of significant correlation between levels and activities of the assayed biochemical components and incidence of damping-off clearly demonstrated that these biochemical components were not involved in the pathogenicity of the tested strains. Therefore, it was hypothesized that the pathogenicity of the tested strains could be due to the effect of cell wall degrading enzymes of pathogenic toxins. Based on the results of the present study, Bacillus strains should be considered in studying the etiology of cotton seedling damping-off.

• Mycobiology
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• v.31 no.2
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• pp.113-118
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• 2003

Solanaceous crops grown in greenhouses and fields in Korea were surveyed from 1994 to 2000. Sclerotinia rot most severely occurred up to 60% in potato. Incidence of the disease was as high as 20% at its maximum in tomato and 5% in eggplant, but as low as less than 1% in red pepper. Symptoms of Sclerotinia rot commonly developed on stems of the solanaceous crops but rarely on fruits of eggplant and tomato. A total of 169 isolates of Sclerotinia species was obtained from the diseased solanaceous crops. Out of the isolates, 165 isolates were identified as S. sclerotiorum, and the others as S. minor based on their morphological and cultural characteristics. S. sclerotiorum was isolated from all the solanaceous crops, while S. minor was only isolated from tomato. Eight isolates of S. sclerotiorum and two isolates of S. minor were tested for their pathogenicity to the solanaceous crops by artificial inoculation. All the isolates of the two Sclerotinia spp. induced rot symptoms on stems of the solanaceous crops tested, which were similar to those observed in the fields. The pathogenicity tests revealed that there was no significant difference in the susceptibility of the solanaceous crops to the isolates of S. sclerotiorum. However, in case of S. minor, the potato cultivar Sumi was relatively less susceptible to the pathogen.

• Mycobiology
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• v.42 no.1
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• pp.66-72
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• 2014

Roselle (Hibiscus sabdariffa L.) family Malvaceae is an important crop used in food, cosmetics and pharmaceutics industries. Roselle is cultivated mainly in Upper Egypt (Qena and Aswan governorates) producing 94% of total production. Root rot disease of roselle is one of the most important diseases that attack both seedlings and adult plants causing serious losses in crop productivity and quality. The main objective of the present study is to identify and characterize pathogens associated with root rot and wilt symptoms of roselle in Qena, Upper Egypt and evaluate their pathogenicity under greenhouse and field condition. Fusarium oxysporum, Macrophomina phaseolina, Fusarium solani, Fusarium equiseti and Fusarium semitectum were isolated from the natural root rot diseases in roselle. All isolated fungi were morphologically characterized and varied in their pathogenic potentialities. They could attack roselle plants causing damping-off and root rot/wilt diseases in different pathogenicity tests. The highest pathogenicity was caused by F. oxysporum and M. phaseolina followed by F. solani. The least pathogenic fungi were F. equiseti followed by F. semitectum. It obviously noted that Baladi roselle cultivar was more susceptible to infection with all tested fungi than Sobhia 17 under greenhouse and field conditions. This is the first report of fungal pathogens causing root rot and vascular wilt in roselle in Upper Egypt.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.112.3-113
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• 2003

More than 30 isolates of Alternaria were obtained from various solanaceous crops in Korea. For all isolates, morphological characteristics of the conidia were determined and compared with those of representative isolates of A. solani and A. tomatophila. Pathogenicity test was performed to Potato, tomato, egg plant and red Pepper and molecular characteristics of them including the representative isolates were determined using sequence analyses of ITS rDNA and histone H3 gene, and URP-PCR analysis. Based on morphological characteristics, the isolates from the solanaceous crops were grouped as identical or very similar to either A. tomatophila(ATO), A. solani(ASO), and unidentified Altemaria sp.(ASP). Among the molecular markers used in this study, the URP-PCR analysis was found to be appropriate for taxonomic resolution of these species. Based on the conidial morphology, pathogenicity test and molecular characteristics, A. tomatophila(early blight of tomato) could be distinguished from A. solani(early blight of potato), and the Alternaria sp.(ASP) from potato, which was closely related to A. solani in conidial morphology, was considered as a new species.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.84.1-84
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• 2003

Magnaporthe grisea, the casual agent of rice blast, forms an appressorium to penetrate its host. Much has been learned about environmental cues and signal transduction pathways, especially those involving CAMP and MAP kinases, on appressorium formation during the last decade. More recently, pharmacological data suggest that calcium/calmodulin-dependent signaling system is involved in its appressorium formation. To determine the role of phosphoinositide-specific phospholipase C (PI-PLC) on appressorium formation, a gene (WPLCl) encoding PI-PLC was cloned and characterized from M. grisea strain 70-15. Sequence analysis showed that MPLCl has alt five conserved domains present in other phospholipase C genes from several filamentous fungi and mammals. Null mutants (mplcl) generated by targeted gene disruption exhibited pleiotropic effects on conidial morphology, appressorium formation, fertility and pathogenicity. mplcl mutants developed nonfunctional appressoria and are also defective in infectious growth in host tissues. Defects in appressorium formation and pathogenicity in mplcl mutants were complemented by a mouse PLCdelta-1 cDNA under the control of the MPLCl promoter. These results suggest that cellular signaling mediated by MPLCl plays crucial and diverse roles in development and pathogenicity of M. grisea, and functional conservation between fungal and mammalian Pl-PLCs.

• The Journal of the Korean Society for Microbiology
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• v.34 no.5
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• pp.471-478
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• 1999

Spirochetes were isolated from the midgut of Ixodes persulcatus ticks captured at Chungju, Korea and identified as Borrelia afzelii strains by polymerase chain reaction. To determine the pathogenicity of the B. afzelii strains isolated in Korea, the microbiological and pathological features of Lyme disease were observed in C3H/He mice after intraperitoneal inoculation of the fresh isolate of B. afzelii strain. The results are summarized as follows 1) The Borrelia were detected in the tissues of heart, spleen, kidney, urinary bladder and knee joint within 7 days after inoculation of infection by dark field microscopic examination. The isolation rate from heart, urinary bladder and joint was significantly higher than the rate from spleen, kidney, and blood samples. 2) The Borrelia was detected in heart muscle by indirect immunofluorescent antibody test. 3) Antibody to the Borrelia was detected as early as one week after inoculation. 4) The marked tropism of the Borrelia was observed in myocardial, urinary tract and joint tissue. The main pathological features are inflammation in tissues of heart, kidney, joint and urinary bladder. From these results, the Borrelia afzelii strain isolated in Korea were determined as pathogenic strain.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.16-20
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• 2006

Four leguminous crops grown in greenhouses and fields in Korea were surveyed from 2000 through 2002. Sclerotinia rot most severely occurred up to $60\%$ in Phaseolus vulgaris grown in greenhouses but occurred as low as $0-0.5\%$ in that grown in fields. Incidence of the disease in Pisum sativum grown in greenhouses ranged $1-5\%$, and that in Vicia Java and Vigna sinensis grown in fields was $0.8\%$ and $2\%$, respectively. Symptoms of Sclerotinia rot commonly developed on stems and pods of the crops. A total of 59 isolates of Sclerotinia species were obtained from diseased stems and pods of the crops. All of the isolates were identified as Sclerotinia sclerotiorum based on their morphological characteristics. Eight isolates of the fungus were tested for their pathogenicity to four host crops by artificial inoculation. All of the isolates induced rot symptoms on stems of the host crops tested, which were similar to those observed in the fields. The pathogenicity tests revealed that there was no significant difference in the susceptibility to the isolates among the leguminous crops tested This is the first formal report that S. sclerotiorum causes the Sclerotinia' rot of the four leguminous crops in Korea.