• The Plant Pathology Journal
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• v.21 no.1
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• pp.47-54
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• 2005

Identification of host genes involved in disease progresses and/or defense responses is one of the most critical steps leading to the elucidation of disease resistance mechanisms in plants. Soybean mosaic virus (SMV) is one of the most prevalent pathogen of soybean (Glycine max). Although the soybeans are placed one of many important crops, relatively little is known about defense mechanism. In order to obtain host genes involved in SMV disease progress and host defense especially for virus resistance, two different cloning strategies (DD RT-PCR and Subtractive hybridization) were employed to identify pathogenesis- and defenserelated genes (PRs and DRs) from susceptible (Geumjeong 1) and resistant (Geumjeong 2) cultivars against SMV strain G7H. Using these approaches, we obtained 570 genes that expressed differentially during SMV infection processes. Based upon sequence analyses, differentially expressed host genes were classified into five groups, i.e. metabolism, genetic information processing, environmental information processing, cellular processes and unclassified group. A total of 11 differentially expressed genes including protein kinase, transcription factor, other potential signaling components and resistant-like gene involved in host defense response were selected to further characterize and determine expression profiles of each selected gene. Functional characterization of these genes will likely facilitate the elucidation of defense signal transduction and biological function in SMV-infected soybean plants.

• The Plant Pathology Journal
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• v.33 no.4
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• pp.402-409
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• 2017

Cyclic dipeptides (CDPs) are one of the simplest compounds produced by living organisms. Plant-growth promoting rhizobacteria (PGPRs) also produce CDPs that can induce disease resistance. Bacillus vallismortis strain BS07 producing various CDPs has been evaluated as a potential biocontrol agent against multiple plant pathogens in chili pepper. However, plant signal pathway triggered by CDPs has not been fully elucidated yet. Here we introduce four CDPs, cyclo(Gly-L-Pro) previously identified from Aspergillus sp., and cyclo(L-Ala-L-Ile), cyclo(L-Ala-L-Leu), and cyclo(L-Leu-L-Pro) identified from B. vallismortis BS07, which induce disease resistance in Arabidopsis against Pseudomonas syringae infection. The CDPs do not directly inhibit fungal and oomycete growth in vitro. These CDPs require PHYTOALEXIN DEFICIENT4, SALICYLIC ACID INDUCTION DEFICIENT2, and NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 important for salicylic acid-dependent defense to induce resistance. On the other hand, regulators involved in jasmonate-dependent event, such as ETHYLENE RECEPTOR1, JASMONATE RESPONSE1, and JASMONATE INSENSITIVE1, are necessary to the CDP-induced resistance. Furthermore, treatment of these CDPs primes Arabidopsis plants to rapidly express PATHOGENESIS-RELATED PROTEIN4 at early infection phase. Taken together, we propose that these CDPs from PGPR strains accelerate activation of jasmonate-related signaling pathway during infection.

• The Plant Pathology Journal
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• v.20 no.1
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• pp.7-12
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• 2004

An important recent advance in the field of plant-microbe interactions has been the cloning of genes that confer resistance to specific viruses, bacteria, fungi or insects. Disease resistance (R) genes encode proteins with predicted structural motifs consistent with them having roles in signal recognition and transduction. Plant disease resistance is the result of an innate host defense mechanism, which relies on the ability of plant to recognize pathogen invasion and efficiently mount defense responses. In tomato, resistance to the pathogen Pseudomonas syringae pv. tomato is mediated by the specific recognition between the tomato serine/threonine kinase Pto and bacterial protein AvrPto or AvrPtoB. This recognition event initiates signaling events that lead to defense responses including an oxidative burst, the hypersensitive response (HR), and expression of pathogenesis- related genes.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.195-201
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• 2015

Plant growth promoting rhizobacteria (PGPR) are known to confer disease resistance to plants. Bacillus sp. JS demonstrated antifungal activities against five fungal pathogens in in vitro assays. To verify whether the volatiles of Bacillus sp. JS confer disease resistance, tobacco leaves pre-treated with the volatiles were damaged by the fungal pathogen, Rhizoctonia solani and oomycete Phytophthora nicotianae. Pre-treated tobacco leaves had smaller lesion than the control plant leaves. In pathogenesis-related (PR) gene expression analysis, volatiles of Bacillus sp. JS caused the up-regulation of PR-2 encoding ${\beta}$-1,3-glucanase and acidic PR-3 encoding chitinase. Expression of acidic PR-4 encoding chitinase and acidic PR-9 encoding peroxidase increased gradually after exposure of the volatiles to Bacillus sp. JS. Basic PR-14 encoding lipid transfer protein was also increased. However, PR-1 genes, as markers of salicylic acid (SA) induced resistance, were not expressed. These results suggested that the volatiles of Bacillus sp. JS confer disease resistance against fungal and oomycete pathogens through PR genes expression.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.13-13
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• 2003

When plants are infected by plant pathogens, rapid cell responses are initiated for further inhibition from fast invasion of pathogens. Hypersensitive response (HR) of plant is well known defense response stopping pathogenesis process through rapid cell death. However, informations on the signaling pathway from reception of pathogen by host plants to appropriate resistant responses are very limited to date. Efficient perception of infection by pathogens and well-programmed signalling mechanism for appropriate responses are important for survival of plants. Plant have developed a sophisticated network(s) of defense/stress responses, among which one of the earliest signalling pathways after perception (of stimuli) is the evolutionary conserved Rop GTPase and mitogen-activated protein kinase (MAPK) cascade.(중략)

• The Plant Pathology Journal
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• v.26 no.1
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• pp.8-16
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• 2010

The phytopathogenic fungus Magnaporthe oryzae is a major limiting factor in rice production. To understand the genetic basis of M. oryzae pathogenic development, we previously analyzed a library of T-DNA insertional mutants of M. oryzae, and identified ATMT0879A1 as one of the pathogenicity-defective mutants. Molecular analyses and database searches revealed that a single TDNA insertion in ATMT0879A1 resulted in functional interference with an annotated gene, MGG00056, which encodes a short-chain dehydrogenase/reductase (SDR). The mutant and annotated gene were designated as $MoSDR1^{T-DNA}$ and MoSDR1, respectively. Like other SDR family members, MoSDR1 possesses both a cofactor-binding motif and a catalytic site. The expression pattern of MoSDR1 suggests that the gene is associated with pathogenicity and plays an important role in M. oryzae development. To understand the roles of MoSDR1, the deletion mutant ${\Delta}Mosdr1$ for the gene was obtained via homology-dependent gene replacement. As expected, ${\Delta}Mosdr1$ was nonpathogenic; moreover, the mutant displayed pleiotropic defects in conidiation, conidial germination, appressorium formation, penetration, and growth inside host tissues. These results suggest that MoSDR1 functions as a key metabolic enzyme in the regulation of development and pathogenicity in M. oryzae.

• The Plant Pathology Journal
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• v.25 no.4
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• pp.417-421
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• 2009

The analysis of the full length genome of Korean isolates of Pepper mottle virus (PepMoV) in previous study showed molecular variations and are found to be related to symptom variation and pathogenicity (Kim et al., 2009, Virus Res. 144:83-88). To fully understand the molecular variation of PepMoV in Korea, we further assessed the role of RNA recombination to biological variation and evolution of PepMoV. Full-length genome of a total of 17 Korean-PepMoV and 2 American (CA and FL) isolates were examined for possible detection of genetic recombination using different recombination detections programs and detected 5 and 8 tentative recombination events using RDP3 and Splits Tree4 programs, respectively. Interestingly, tentative recombinants detected such as isolates 57, 134 and 217 were previously identified as severe isolates and 205135 and 205136 as differentiating isolates (Kim et al., 2009, Virus Res. 144:83-88). In addition, recombination was frequently detected in the Vb isolate, the first PepMoV isolate reported in Korea, suggesting significant involvement in the evolution of PepMoV in Korea. These initial results of our recombination analyses among PepMoV isolates in Korea may serve as clues to further investigate the biological variations and evolution of PepMoV brought about by recombination.

• The Plant Pathology Journal
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• v.25 no.4
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• pp.400-407
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• 2009

A pathogenesis-related protein (PgPR5) gene that isolated from the leaf of Panax ginseng was characterized. The ORF is 756 bp with a deduced amino acid sequence of 251 residues. The calculated molecular mass of the matured protein is approximately 27.5 kDa with a predicated isoelectric point of 7.80. A GenBank BlastX search revealed that the deduced amino acid of PgPR5 shares highest sequence similarity to PR5 of Actinidia deliciosa (80% identity, 87% similarity). PgPR5 has a C-terminal and N-terminal signal peptide, suggesting that it is a vacuolar secreted protein. The expression of PgPR5 under various environmental stresses was analyzed at different time points using real-time PCR. Our results reveal that PgPR5 is induced by salt stress, chilling stress, heavy metal, UV, and pathogen infection. These results suggest that the PgPR5 could play a role in the molecular defence response of ginseng to abiotic and pathogen attack. This is the first report of the isolation of PR5 gene from the P. ginseng.

• Korean Journal Plant Pathology
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• v.10 no.4
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• pp.305-313
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• 1994

Typically susceptible lesions were developed on pepper (cv. Hanbyul) leaves inoculated with the compatible strains Ds 1 of Xanthomonas campestris pv. vesicatoria. The lesions appeared first water-soaked and then turned yellow with a chlorotic area. In contrast, the leaves inoculated with the incompatible strain 81-23 initially turned yellow and then developed local necrosis. Multiplication of x. c. pv. vesicatoria in pepper leaves also were distinctly different between the two strains. The strain Ds 1 multiplied more greatly than did the strain 81-23 in the infected leaves. X. c. pv. vesicatoria infection of pepper leaves induced the synthesis of soluble proteins, especially more greatly in the compatible than in the incompatible interactions. Some pathogenesis-related (PR) proteins were detected in the intercellular washing fluid (IWF) and extracts of the infected pepper leaves. In particular, the 32 kDa protein on SDS-PAGE gels appeared intensely in the incompatible interaction. In contrast, some proteins with moluecular masses of 65, 71, and 75 kDa disappeared in the infected pepper leaves. Isoelectric focusing could identify the pIs of soluble proteins in infected pepper leaves. The accumulation of the IWF from infected leaves was more conspicuous in the incompatible than the compatible interaction. These results suggest that some extremely acidic and basic proteins were induced and accumulated in the intercellular spaces of infected pepper leaves.

• The Plant Pathology Journal
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• v.27 no.2
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• pp.120-127
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• 2011

While many isolates of Alternaria alternata are common saprophytes on trees and shrubs, this study clearly demonstrated that A. alternata is a primary pathogen in lilac (Syringa sp.), causing a leaf-blight that affects different Syringa species. Isolates of Alternaria sp. were collected from leaf blight samples of lilacs in the field. The internal transcribed spacer (ITS) region and morphological characterization were used to identify lilac blight pathogen. Based on 100% ITS nucleotide sequence identities to the Alternaria genus in the GenBank and morphological features, these isolates were identified as A. alternata. Disease symptoms were reproduced in lilac plants inoculated with A. alternata mycelial plugs and sprayed with a fungus-free culture filtrate, indicating that pathogenesis in lilac involves secondary metabolites or toxins. Diagnostic primers were developed to detect Alternaria sp. and A. alternata in lilac leaf blight based on ITS region and four known genes associated with pathogenesis in A. alternata: mixed-linked glucanase precursor, endopolygalacturonase, hsp70, and histone genes. The results from our study indicated A. alternata is a primary pathogen in lilac leaf blight, and these diagnostic primers can be used as a tool for the fast detection of A. alternata associated with lilac leaf blight.