• The Plant Pathology Journal
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• v.15 no.5
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• pp.295-301
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• 1999

Many of plant defense responses are consequence of transcriptional activation of related genes. We have developed a modified differential screening procedure to isolate tobacco genes that are involved in the defense responses against TMV infection. A cDNA library was constructed from Nicotiana glutinosa leaves infected by TMV under temperature shift conditions. Each of plasmid DNA in the library was hybridized on a set of slot blots to a pool of cDNA probes prepared from either TMV-infected or mock-treated tobacco leaves. Among 900 plasmid DNAs, 81 clones exhibiting significantly enhanced or reduced level of hybridization to either probe were selected for nucleotide sequencing. The clones were listed into 61 genes considering redundancy between the sequences. The genes were identified to be defense-related genes including PR-genes and genes involved in primary or secondary metabolisms. This results supports the implication that plant defense process entails a major shift in total cellular metabolisms rather than activation of a limited number of defense-related genes. Expression patterns of a number of defense-related genes. Expression patterns of a number of selected genes were examined in northern blot analyses. It is notable that the clone 630 of unknown function exhibits expression pattern similar to those of previously known PR-genes. Experiments to elucidate the roles in defense mechanism of a couple of genes newly identified in this study are in progress.

• The Plant Pathology Journal
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• v.15 no.1
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• pp.8-13
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• 1999

Hypersensitive cell death of plants during incompatible plant-pathogen interactions is one of the efficient defense mechanisms of plants against pathogen infections. For better understanding of the molecular mechanisms involved in the plant hypersensitive response (HR), TMV-induced biotic plant cell death and CuSO4-induced abiotic plant cell death were compared in terms of expression patterns of ten different defense-related genes as molecular markers. The genes include five pathogenesis-related protein genes, two plant secondary metabolite-associated genes, two oxidative stress-related genes and one wound-inducible gene isolated from tobacco. Northern blot analyses revealed that a same set of defense-related genes was induced during both biotic and abiotic cell death but with different time and magnitude. The expression of defense-related genes in tobacco plants was temporarily coincided with the time of cell death. However, when suspension cell cultures was used to monitor the expression of defense-related genes, different patterns of the gene expression were detected. This result implies that three are common and, in addition, also different branches of signaling pathways leading to the induced expression of defense-related genes in tobacco during the pathogen- and heavy metal-induced cell death.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.64.1-64
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• 2003

Inoculation of primary pepper leaves with an avirulent strain of Xanthomonas campestris pv. vesicatoria induced systemic acquired resistance (SAR) in secondary leaves. This SAR response was accompanied by the systemic expression of defense-related genes, a systemic microoxidative burst generating H2O2, and the systemic induction of ion-leakage and callose deposition in the non-inoculated, secondary leaves. Some defense-related genes encoding PR-1, chitinase, peroxidase, PR10, thionin, defensin and zinc-finger protein were distiilctly induced in the systemic leaves. The systemically striking accumulation of H$_2$O$_2$and strong increase in peroxidase activity in pepper was suggested to contribute to the triggering of cell death In the systemic micro-HRs, leading to the induction of SAR. Treatment of non-inoculated, secondary leaves with diphenylene iodinium (DPI), an inhibitor of the oxidative burst, substantially reduced the induction of some defense-related genes and subsequently SAR.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.208-219
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• 2017

Heterosis or hybrid vigor describes a phenomenon that superior phenotypes compared to the two parents are observed in the heterozygous $F_1$-hybrid plants. Identification and characterization of heterosis-related genes (HRGs) will facilitate hybrid breeding in crops. To identify HRGs in Brassica rapa, we analyzed transcriptome profiling using a Br300K microarray in non-heading Chinese cabbage at three developmental stages. A large number of genes were differentially expressed in $F_1$ hybrids and non-additive expression was prominent. Genes that are expressed specifically for $F_1$ hybrid at all three stages were Brassica-specific uncharacterized genes and several defense-related genes. Expression of several photosynthesis- and stress-related genes were also $F_1$ hybrid-specific. Thirteen NBS-LRR class genes showed high and specific expression in $F_1$ hybrid Shulu: some of them were characterized as defense genes in Arabidopsis, but most have not been. Further characterization of these defense-related genes in Brassica species and its application will be helpful for understanding the role of defense responses in heterosis. In addition, results obtained in this study will be valuable to develop molecular markers for heterosis and disease resistance in B. rapa.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.110-115
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• 2013

Theobroxide, a novel compound isolated from a fungus Lasiodiplodia theobromae, stimulates potato tuber formation and induces flowering of morning glory by initiating the jasmonic acid synthesis pathway. To elucidate the effect of theobroxide on pathogen resistance in plants, Nicotiana benthamiana plants treated with theobroxide were immediately infiltrated with Pseudomonas syringae pv. tabaci. Exogenous application of theobroxide inhibited development of lesion symptoms, and growth of the bacterial cells was significantly retarded. Semiquantitative RT-PCRs using the primers of 18 defense-related genes were performed to investigate the molecular mechanisms of resistance. Among the genes, the theobroxide treatment increased the expression of patho-genesis-related protein 1a (PR1a), pathogenesis-related protein 1b (PR1b), glutathione S-transferase (GST), allen oxide cyclase (AOC), and lipoxyganase (LOX). All these data strongly indicate that theobroxide treatment inhibits disease development by faster induction of defense responses, which can be possible by the induction of defense-related genes including PR1a, PR1b, and GST triggered by the elevated jasmonic acid.

• Journal of Ginseng Research
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• v.35 no.1
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• pp.1-11
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• 2011

Korean ginseng is a medicinally important perennial herb from the family Araliaceae. It has been cultivated for its highly valued medicinal properties for over 1,000 years in east Asian countries such as China, Korea, and Japan. Due to its longtime cultivation in shady areas, ginseng is frequently exposed to pathogenic infections. Plants protect themselves from microbial pathogens using an array of defense mechanisms, some of which are constitutively active, while others are activated upon pathogen invasion. These induced defense responses, controlled by defense-related genes, require tradeoffs in terms of plant fitness. We hypothesize that ginseng, as with other plants, possesses regulatory mechanisms that coordinate the activation of attacker-specific defenses in order to minimize fitness costs while attaining optimal resistance. Several classes of defense-related genes are induced by infection, wounds, irradiation, and other abiotic stresses. Both salicylates and jasmonates have been shown to cause such responses, although their specific roles and interactions in signaling and development are not fully understood in ginseng. This review summarizes possible defense-related genes in ginseng based on their expression patterns against biotic and abiotic stresses and describes their functional roles.

• BMB Reports
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• v.49 no.12
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• pp.693-698
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• 2016

In this study, a tissue-specific GAL4/UAS activation tagging system was used for the characterization of genes which could induce lethality when ubiquitously expressed. A dominant mutant exhibiting stunted growth was isolated and named defective root development 1-D (drd1-D). The T-DNA tag was located within the promoter region of AtTX12, which is predicted to encode a truncated nucleotide-binding leucine-rich repeat (NLR) protein, containing a Toll/interleukin-1 receptor (TIR) domain. The transcript levels of AtTX12 and defense-related genes were elevated in drd1-D, and the misexpression of AtTX12 recapitulated the drd1-D phenotypes. In the presence of ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), a key transducer of signals triggered by TIR-type NLRs, a low-level of AtTX12 misexpression induced strong defective phenotypes including seedling lethality whereas, in the absence of EDS1, a high-level of AtTX12 misexpression induced weak growth defects like dwarfism, suggesting that AtTX12 might function mainly in an EDS1-dependent and partially in an EDS1-independent manner.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.450-458
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• 2020

Pepper and tomato plants infected with two Clavibacter species, C. capsici and C. michiganensis have shown different patterns of disease development depending on their virulence. Here, we investigated how pepper and tomato plants respond to infection by the high-virulent or low-virulent Clavibacter strains. For this, we chose two strains of each Clavibacter species to show different virulence level in the host plants. Although low-virulent strains showed less disease symptoms, they grew almost the same level as the high-virulent strains in both plants. To further examine the response of host plants to Clavibacter infection, we analyzed the expression patterns of plant defense-related genes in the leaves inoculated with different strains of C. capsici and C. michiganensis. Pepper plants infected with high-virulent C. capsici strain highly induced the expression of CaPR1, CaDEF, CaPR4b, CaPR10, and CaLOX1 at 5 days after inoculation (dai), but their expression was much less in low-virulent Clavibacter infection. Expression of CaSAR8.2 was induced at 2 dai, regardless of virulence level. Expression of GluA, Pin2, and PR2 in tomato plants infected with high-virulent C. michiganensis were much higher at 5 dai, compared with mock or low-virulent strain. Expression of PR1a, Osmotin-like, Chitinase, and Chitinase class 2 was increased, regardless of virulence level. Expression of LoxA gene was not affected by Clavibacter inoculation. These results suggested that Clavibacter infection promotes induction of certain defense-related genes in host plants and that differential expression of those genes by low-virulent Clavibacter infection might be affected by their endophytic lifestyle in plants.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.29-29
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• 2003

Incompatible plant-pathogen interactions result in the rapid cell death response known as hypersensitive response (HR) and activation of host defense-related genes. To understand the molecular and cellular mechanism controlling defense response better, several approaches including isolation and characterization of novel genes, promoter analysis of those genes, protein-protein interaction analysis and reverse genetic approach etc. By using the yeast two-hybrid system a clone named Tsipl, Tsil -interacting protein 1, was isolated whose translation product apparently interacted with Tsil, an EREBP/AP2 type DNA binding protein. RNA gel blot analysis showed that the expression of Tsipl was increased by treatment with NaCl, ethylene, salicylic acid, or gibberellic acid. Transient expression analysis using a Tsipl::smGFP fusion gene in Arabidopsis protoplasts indicated that the Tsipl protein was targeted to the outer surface of chloroplasts. The targeted Tsipl::smGFP proteins were diffused to the cytoplasm of protoplasts in the presence of salicylic acid (SA) The PEG-mediated co-transfection analysis showed that Tsipl could interact with Tsil in the nucleus. These results suggest that Tsipl-Tsil interaction might serve to regulate defense-related gene expression. Basically the useful promoters are valuable tools for effective control of gene expression related to various developmental and environmental condition.(중략)

• Korean Journal Plant Pathology
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• v.14 no.3
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• pp.278-285
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• 1998

Effects of chitosan on growth of tomato plant, and suppression of Fusaruim wilt caused by Fusarium oxysporum f. sp. lycopersici and late blight casued by Phytophthora infestans, were examined. Both late blight and fusarium wilt were suppressed by spray and irrigation of chitosan, respectively. Inhibition of mycelial growth was not greatly affected by molecular size of chitosan but, concentration dependent effects was observed. Ninty percent of P. infestans and 80% of F. oxysporum f. sp. lycopersici of mycelial growth was inhibited by 1,000 ppm of chitosan (MW 30,000~50,000) when amended in plate media. Induction of defense-related gene expression in plant by chitosan treatments were observed when chitosan treated tobacco and tomato RNA samples were hybridized with several defense-related genes as probes. The results revealed that $\beta$-1,3-glucanase and chitinase genes were strongly induced, while pathogenesis-related protein-1, 3-hydroxy-3-methylglutaryl coenzyme A reductase, anionic peroxidase, phenylalanine ammonia lyase genes were weakly induced by chitosan treatment. These results suggest that chitosan have dual effects on these host-pathogen interactions. Possible roles of chitosan in suppression of tomato diseases by inhibition of mycelial growth and activation of plant defense responses are discussed.