• Plant Biotechnology Reports
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• 제5권3호
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• pp.283-287
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• 2011

In order to produce centellosides from whole plant cultures of Centella asiatica (L.) Urban, we evaluated the synergistic effects of thidiazuron (TDZ) and methyl jasmonate (MJ) on whole plant growth and centelloside production. After 4 weeks of treatment with 0.025 mg/L of TDZ coupled with 0.1 mM MJ, the production of made-cassoside and asiaticoside from whole plant cultures was estimated to be 2.40- and 2.44-fold, respectively, above that of MJ elicitation alone. When whole plants were treated with a growth regulator and an elicitor, the growth of whole plants, as compared to the controls, did not differ. Additionally, total phytosyterol content in the leaves of whole plants co-treated with MJ and TDZ was 1.08-fold greater than those of MJ alone. These results demonstrate that combined treatments not only stimulate the accumulation of centellosides in the leaves but also inhibit the reduction of phytosterol levels caused by MJ elicitation.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1995년도 Proceedings of special lectures on Molecular Biological Approaches to Plant Disease National Agricultural Science and Technology Institute Suwon, Korea
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• pp.55-75
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• 1995

Induction of HMG-Co A reductase (HMGR) is essential for the biosynthesis of sesquiterpenoid phytoalexins and steroid derivatives in Solanaceous plants following wounding and pathogen infection. To better understand this complex step in stress-responsive isoprenoid synthesis, three classes of cDNAs for HMGR (hmg1, hmg2, and hmg3) were isolated from a potato tuber library. The potato cDNAs had extensive homology in open reading frames but had low homology in the 3'-untranslated regions. RNA gel blot analysis using gene-specific probes revealed that hmg1 is induced by wounding but wound induction is strongly suppressed by arachidonic acid or by inoculation with Phytophthora infestants. In contrast, hmg2 and hmg3 are slightly induced by wounding and strongly enhanced by arachidonic acid or inoculation. The induction and suppression of HMGR genes parallel the suppression of steroid and stimulation of sesquiterpenoid accumulations observed in earlier investigations. Treatment of the tuber disks with a low concentration of methyl-jasmonate doubled the wound induced accumulation of hmg1 transcripts and steroid-glycoalkaloid accumulation, but did not affect the abundance of transcripts for hmg2 or hmg3 nor induce phytoalexins. High concentration of methyl-jasmonate suppressed hmg1 mRNA and steroid-glycoalkaloid accumulation, induced hmg3 mRNA, and did not elicit phytoalexins. Lipoxygenase inhibitors suppressed the accumulation of of hmg1 transcripts and steroid-glycoalkaloids, which were restored by exogeneous methyl-jasmonate. Methyl-jasmonate applied together with arachidonic acid enhanced the elicitor induced accumulation of sesquiterpenes and sustained steroid-glycoalkaloid levels with transcript levels for the various HMGR mRNAs equal to or greater than wound-only treatment. These results domonstrate that the consequences of wound- and pathogen-responses of plants are different at the levels of gene expression and associated secondary metabolism.

• The Plant Pathology Journal
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• 제29권1호
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• pp.17-30
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• 2013

Barley stripe mosaic virus (BSMV) induces massive actin filament thickening at the infection front of infected Nicotiana benthamiana leaves. To determine the mechanisms leading to actin remodeling, fluorescent protein fusions of the BSMV triple gene block (TGB) proteins were coexpressed in cells with the actin marker DsRed: Talin. TGB ectopic expression experiments revealed that TGB3 is a major elicitor of filament thickening, that TGB2 resulted in formation of intermediate DsRed:Talin filaments, and that TGB1 alone had no obvious effects on actin filament structure. Latrunculin B (LatB) treat-ments retarded BSMV cell-to-cell movement, disrupted actin filament organization, and dramatically decreased the proportion of paired TGB3 foci appearing at the cell wall (CW). BSMV infection of transgenic plants tagged with GFP-KDEL exhibited membrane proliferation and vesicle formation that were especially evident around the nucleus. Similar membrane proliferation occurred in plants expressing TGB2 and/or TGB3, and DsRed: Talin fluorescence in these plants colocalized with the ER vesicles. TGB3 also associated with the Golgi apparatus and overlapped with cortical vesicles appearing at the cell periphery. Brefeldin A treatments disrupted Golgi and also altered vesicles at the CW, but failed to interfere with TGB CW localization. Our results indicate that actin cytoskeleton interactions are important in BSMV cell-to-cell movement and for CW localization of TGB3.

• 한국약용작물학회지
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• 제10권2호
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• pp.88-92
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• 2002

대황(Rheum undulatum L.)의 형질전환된 뿌리의 기내(in vitro)배양으로부터 quinone계 알칼로이드 물질인 anthraquinone의 생산성을 확인하고자 하였다. 형질전환된 뿌리로부터 anthraquinone의 생산에 있어서 배지, 초기 pH, 탄소원의 농도, 광 그리고 elicitors의 영향을 조사 하였다. 형질전환된 뿌리는 6% sucrose와 0.5 mg/l $GA_3$ 그리고 50 mg/l chitosan이 첨가된 WPM 배지에 치상한 후 16/8의 광조건$(16{\mu}mol\;m^2s^1)$하에서 배양시 0.18 mg(생중량)의 anthraquinone의 생산성을 보여주었다. 이와같은 함량은 재배근의 약 1.3배에 해당된다.

• 한국환경농학회지
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• 제17권1호
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• pp.39-42
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• 1998

사탕수수 찌거기를 여름느타리에 의해 발효한 후 부산물의 추출물로부터 생물학적 활성을 조사하기 위하여, 항종양성, 콩에 있어서의 glyceollin 유도성 및 완두에 있어서의 줄기 성장성을 관찰하였다. 알콜추출분획 및 DMSO분획물은 자실체 추출분획보다는 약했지만 매우 좋은 항종양성을 나타내었다. 콩의 자엽실험에서는 모든 추출물이 식물체로 하여금 병원성 감염을 방지할 수 있는 glyceollin 유도성을 갖고 있었다. 또한 IAA 유도 줄기성장 실험에서는 양성반응을 보인 모든 실험군에서 IAA와 추출물간의 유도 상승효과가 있는 것으로 나타났다.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1998년도 The 12th Symposium on Plant Biotechnology Vol.12
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• pp.10-18
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• 1998

For improvement of plants in disease resistance, it is most important to elucidate the mechanism to perceive and respond to the signal molecules of invaders. A model system with pea and its pathogen, Mycosphaerella pinodes, showed that the fungal elicitor induced defense responses in all plant species tested but that the suppressor of the fungus blocked or delayed the expression of defense responses and induced accessibility only in the host plant. In the world, many researchers believe that the pathogens` signals are recognized only on the receptors in the plasma membranes. Though we found that the ATPase and polyphosphoinositide metabolism in isolated plasma membranes responded to these fungal signals, we failed to detect specific actions of the suppressor in vitro on these plasma membrane functions. Recently, we found that ATPase (NTPases) and superoxide generating system in isolated cell wall were regulated by these fungal signals even in vitro, especially, by the suppressor in a strictly species-specific manner and also that the cell wall alone prepared an original defense system. The effects of both fungal signals on the isolated cell wall functions in vitro coincide perfectly with those on defense responses in vivo. In this treatise, we discuss the key role of the cell wall, which is plant-specific and the most exterior organelle, in determining host-parasite specificity and molecular target for improvement of plants.

• Molecules and Cells
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• 제19권3호
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• pp.418-427
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• 2005

When inoculated into sensitive tobacco Xanthi-nn plants, the crucifer and garlic-infecting Tobacco mosaic virus (TMV-Cg) induces local necrotic lesions that resemble those seen in the hypersensitive response (HR) of resistant tobacco plants. However, unlike these, tobacco Xanthi-nn plants do not become resistant to infection and the virus spreads systemically causing a severe disease characterized by necrotic lesions throughout the plant. To identify the viral protein that elicits this necrotic response, we used a set of hybrid viruses constructed by combination of TMV-Cg and the tobacco mosaic virus strain U1 (TMV-U1). In this study we present evidence that the coat protein of TMV-Cg (CPCg) is the elicitor of the necrotic response in tobacco Xanthi-nn plants. Local and systemic necrotic lesions induced by TMV-Cg and by the hybrid U1-CPCg -that carries CPCg in a TMV-U1 context- are characterized by cell death and by the presence of autoflorescent phenolic compounds and $H_2O_2$, just like the HR lesions. In addition, defense-related genes and detoxifying genes are induced in tobacco Xanthi-nn plants after TMV-Cg and U1-CPCg inoculation. We postulate that in our system, CPCg is recognized by sensitive tobacco plants that mount an incomplete defense response. We call this an HR-like since it is not enough to induce plant resistance.

• 식물조직배양학회지
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• 제24권5호
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• pp.273-277
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• 1997

Rhizoctonia solani 추출물(elicitor)을 Hyoscyamus muticus 모상근배양에 처리하였을 때 sesquiterpene cyclase (SC)가 유도됨과 동시에 sesquiterpene화합물이 합성되어 배양액속에 축적하는 것으로 나타났다. 24시간 배양기간 동안 배양액으로부터 sesquiterpene을 추출ㆍ분리하여 배양할 경우, 추출ㆍ분리하지 않은 모상근배양보다 거의 두배의 함량이 생성되었다. Cyclase monoclonal antibody을 이용하여 immunoblot을 시도한 결과, 추출한 모상근배양과 추출하지 많은 모상근배양에서의 SC 절대량은 동일한 것으로 나타났으며, 효소활성도 현저한 차이가 없는 것으로 측정되었다. 이러한 결과는 terpenoid pathway에서 sesquiterpene 생합성이 이용가능한 기질의 량에 의해 조절되는 것으로 사료되며, feedback 조절은 sesquiterpene cyclase 효소에 앞서 일어나는 것으로 추정된다.

• The Plant Pathology Journal
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• 제23권1호
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• pp.22-25
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• 2007

Biocontrol activity of five strains of selected rhizo-bacteria were tested in tomato against bacterial wilt caused by Ralstonia solanacearum. After root bacterization the plants were grown in a perlite-hydroponic system. Upon challenge inoculation with the pathogen, all of the rhizobacterial strains efficiently suppressed the bacterial wilt in tomato in various rates, at maximum by the strain, Bacillus vallismortis strain EXTN-1. While the percent of infected plants in the non-bacterized control plants were 95%, it was only 65% in plants pre-treated with EXTN-1. It was also demonstrated that the movement of R. solanacearum within the stem was significantly hampered when the plants were root bacterized. As EXTN-1 has no antagonistic properties against R. solanacearum, the bacterial wilt was probably suppressed by a mechanism other than antibiosis. Previously, the strain had been proven to produce an efficient elicitor for inducing systemic resistance in many crops. As the present study confirmed that EXTN-1 has the ability for reducing the pathogen spread in tomato, the strain could be effectively used as a potential biocontrol agent against bacterial wilt.

• The Plant Pathology Journal
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• 제36권3호
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• pp.255-266
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• 2020

Plant immune responses can be triggered by chemicals, microbes, pathogens, insects, or abiotic stresses. In particular, induced systemic resistance (ISR) refers to the activation of the immune system due to a plant's interaction with beneficial microorganisms. The phenolic compound, 2,4-diacetylphloroglucinol (DAPG), which is produced by beneficial Pseudomonas spp., acts as an ISR elicitor, yet DAPG's mechanism in ISR remains unclear. In this study, transgenic Arabidopsis thaliana plants overexpressing the DAPG hydrolase gene (phlG) were generated to investigate the functioning of DAPG in ISR. DAPG was applied onto 3-week-old A. thaliana Col-0 and these primed plants showed resistance to the pathogens Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000. However, in the phlG transgenic A. thaliana, the ISR was not triggered against these pathogens. The DAPG-mediated ISR phenotype was impaired in transgenic A. thaliana plants overexpressing phlG, thus showing similar disease severity when compared to untreated control plants. Furthermore, the DAPG-treated A. thaliana Col-0 showed an increase in their gene expression levels of PDF1.2 and WRKY70 but this failed to occur in the phlG transgenic lines. Collectively, these experimental results indicate that jasmonic acid/ethylene signal-based defense system is effectively disabled in phlG transgenic A. thaliana lines.