• Journal of Plant Biotechnology
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• v.36 no.3
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• pp.219-223
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• 2009

Oxidative stress derived from excess reactive oxygen species (ROS) is a major damaging factor for plants exposed to environmental stresses. Sweetpotato [Ipomoea batatas (L.) Lam] has a relatively broad adaptability to harsh environmental conditions compared to other staple crops. In this study, to select stress-tolerant sweetpotato cultivars for sources of molecular breeding on marginal lands, we evaluated the ion leakage values in 10 different cultivars after treatment of methyl viologen (MV), an ROS-generating nonselective herbicide, to leaf discs. DPPH radical scavenging activity and the contents of total phenolics were also investigated. The ion leakage of each cultivar showed a diverse value, which is well correlated with DPPH radical scavenging activity of each cultivar. DPPH radical scavenging activity also showed a high corelation with the contents of total phenolic contents. Three cultivars of Yanshu 8, Shinhwangmi and Shinzami showed high antioxidant activity. Our results suggest that a simple and efficient DPPH radical scavenging activity would be a suitable method to select potential cultivars with enhanced tolerance to multiple environmental stress.

• The Korean Journal of Ecology
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• v.19 no.2
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• pp.151-163
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• 1996

To investigate the early symptoms of light-chilling, alterations of chlorophyll fluorescence transients were monitored in cucumber (Cucumis sativus L. cv. Ilmichungjang) leaves. During 24 h chilling, decreases in (Fv)m/Fm, qE and qQ, and an increase in Fo were observed. The chilling effects were not recovered at room temperature, and a significant increase in Fo was observed during the recovery period. After 6 h chilling, ‘dip’(D) level of the transients became obscure, and the negative slope after ‘peak’(P) disappeared. The first derivative (dFv/dt) of the fast fluorescence rise curve was used to obtain more accurate information about the changes in the transients. The maximal rate of the fluorescence increase in the D-p rise curve (Fr) has been the most frequently used chilling stress indicator. However, a correct value of Fr could not be measured when the D level became obscure. This problem was overcome by introducing a new indicator, HFr (dFv/dt at Fv = 1/2 (Fv)m), and HFr gave very similar values to Fr. To monitor the changes in curvature around D level, another new parameter, ${\Delta}S$(D-Fr), was also introduced. These three parameters decreased very sensitively during light-chilling. In addition, increases in these parameters were observed during the first 2 h chilling, but this increase in Fr was also observed in pea leaf discs dark-chilled for 15 min, suggesting that this very early change is a common response to chilling in both pea and cucumber leaves. Quenching coefficients were also very sensitive to chilling, especially qE. Discussion on the usage of these parameters as chilling stress indicators is given in the text.

• BMB Reports
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• v.34 no.4
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• pp.316-321
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• 2001

Dehydroascorbate (DHA) reductase (DHAR, EC 1.8.5.1) catalyzes the reduction of DHA to reduced ascorbate (AsA) using glutathione (GSH) as the electron donor in order to maintain an appropriate level of ascorbate in plant cells. To analyze the physiological role of DHAR in environmental stress adaptation, we developed transgenic tobacco (Nicotiana tabacum cv. Xanthi) plants that express a human DHAR gene isolated from the human fetal liver cDNA library in the chloroplasts. We also investigated the DHAR activity, levels of ascorbate, and GSH. Two transgenic plants were successfully developed by Agrobacterium-mediated transformation and were confirmed by PCR and Southern blot analysis. DHAR activity and AsA content in mature leaves of transgenic plants were approximately 1.41 and 1.95 times higher than in the non-transgenic (NT) plants, respectively In addition, the content of oxidized glutathione (GSSG) in transgenic plants was approximately 2.95 times higher than in the NT plants. The ratios of AsA to DHA and GSSG to GSH were changed by overexpression of DHAR, as expected, even though the total content of ascorbate and glutathione was not significantly changed. When tobacco leaf discs were subjected to methyl viologen at $5\;{\mu}M$, $T_0$ transgenic plants showed about a 50% reduction in membrane damage compared to the NT plants.

• BMB Reports
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• v.29 no.5
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• pp.398-404
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• 1996

Light-chilling effects were investigated in chilling-sensitive cucumber (Cucumis sativus L. cv. Ilmichungjang) and chilling-resistant pea (Pisum sativum L. cv. Giant) leaf discs in relation to possible damage in D1 protein. In both plants, dark-chilling did not cause any noticeable changes in (Fv)m/Fm and lincomycin did not affect the decrease in (Fv)m/Fm caused by light-chilling. This result suggests that the de novo synthesis of D1 protein did not occur actively during light-chilling. In pea light-chilled for 6 h. the decreased (Fv)m/Fm was partly recovered in the dark, and almost complete recovery was observed in the light. In cucumber light-chilled for 3 h. the reduced (Fv)m/Fm decreased further for the initial 2 h recovery process in the light regardless of the treatment of lincomycin and recovered very slowly. In both plant species, the treatment of lincomycin inhibited the recovery process in the light, but did not significantly inhibit the process in the dark. In cucumber leaves pulse-labeled with $[^{35}S]Met$, the labeled band intensities of isolated pigment-protein complexes were almost the same during the 6 h light-chilling, but significant decreases in band intensities were observed during the 3 h recovery period. This result suggests that the irreversibly damaged D1 protein was degraded during the recovery period. However, no noticeable changes were observed in the pea leaves during the 12 h chilling and 3 h recovery period. The polyacrylamide gel electrophoresis of the pigment-protein complexes showed that the principal lesion sites of light-chilling were different from those of room temperature photoinhibition.

• Journal of Plant Biotechnology
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• v.31 no.2
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• pp.109-113
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• 2004

In order to develop transgenic potato plants with enhanced tolerance to multiple stress, we constructed the transformation vector expressing both superoxide dismutase and ascorbate peroxidase genes in chloroplasts under the control of a stress-inducible SWPA2 promoter. Transgenic potato plants (cv. Superior and Atlantic) were generated using an Agrobacterium-mediated transformation system. Transgenic potato plants were regenerated on MS medium containing 100mg/L kanamycin. Genomic Southern blot analysis confirmed the incorporation of foreign genes into the potato genome. When potato leaf discs were subjected to methyl viologen (MV) at 10 $\mu$M, transgenic plants showed higher tolerance than non-transgenic or vector-transformed plants. To further study we selected the transgenic plant lines with enhanced tolerance against MV. These plants will be used for further analysis of stress-tolerance to multiple environmental stresses.

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.54-62
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• 2004

The selective toxicity of spirodiclofen and fluacrypyrim+tetradifon to the predatory mite, Phytoseiulus persimilis and the tea red spider mite, Tetranychus kanzawai was evaluated. The bean leaf discs with adult females or eggs of both species were sprayed with several concentrations of spirodiclofen or fluacrypyrim+tetradifon. Spirodiclofen and fluacrypyrim+tetradifon were much less toxic to P. persimilis than to T. kanzawai. Although the survival rate of adult females of P. persimilis tended to decrease with increasing concentrations of spirodiclofen, 92-68% of predators survived at concentrations of 22.5-180 ppm. Likewise, reproduction was reduced with increasing spirodiclofen concentration. Spirodiclofen did not affect the hatch of P. persimilis eggs. Survival of immature predators decreased with increasing spirodiclofen concentration, however, 88-20% of immature predators reached adulthood at 22.5-90 ppm. In the case of fluacrypyrim+tetradifon, the survival rate of adult females of P. persimilis tended to decrease with increasing concentrations of fluacrypyrim+tetradifon. However, 94-72% of predators remained alive at concentrations of 22.5-180 ppm. Likewise, reproduction was reduced with increasing fluacrypyrim+tetradifon concentration. Fluracypyrim+tetradifon did not affect the hatch of P. persimilis eggs. Survival of immature predators decreased with increasing fluacrypyrim+tetradifon concentration, however, 100-86% of immature predators reached adulthood at 22.5-180 ppm. Based on the results, spirodiclofen and fluacrypyrim+tetradifon appeared to be promising candidates for use in integrated mite management programs where P. persimilis is the major natural enemy.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.51-58
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• 2015

Thirty one of Staphylococcus aureus isolated from perilla leaf cultivation areas in Miryang were investigated on the characteristics, such as enterotoxin genes and antibiotic susceptibility. Five toxin genes (sea, seb, sec, sed, and see) were examined by PCR method. Disc diffusion method was used to examine the antibiotic susceptibility of S. aureus by using 18 types of antibiotic discs with different concentrations. Among enterotoxin-encoding genes, sea and sed genes were co-detected from 4 isolates (12.9%), sed gene was founded in 9 isolates (29.0%), and see gene was founded in 1 isolate (3.2%). However seb and sec and tsst were not detected in any isolates. As a result of antibiotic susceptibility test, 7 isolates (22.6%) were resistant to 12 antibiotics (penicillin, ampicillin, oxacillin, amoxicillin-clavulanic acid, cefazolin, cephalothin, imipenem, gentamicin, tetracycline, ofloxacin, norfloxacin, and erythromycin). 2 isolates (6.5%) were resistant to 5 antibiotics (penicillin, ampicillin, amoxicillin-clavulanic acid, gentamycin, and telithromycin). MRSA (Methicilline Resistant Staphylococcus aureus) was founded in packing vinyl, hands, and perilla leaves.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.180-185
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• 2015

Leaf discs from 'Yeobong' and 'Maehyang' strawberry plants were used as explants for transformation. The Agrobacterium tumefaciens strain EHA105 harboring the monellin gene under the control of the CaMV 35S promoter was used in co-cultivation experiments. The frequencies of callus formation and plant regeneration from leaf explants after co-cultivation in 'Yeobong' were higher than those of 'Maehyang'. These transgenic plants showed normal growth patterns and flowering. PCR and Southern hybridization confirmed that 1 to 2 copies of the monellin gene were integrated into genome of the transgenic strawberry plants. Northern blot analysis confirm that the transcripts were expressed in transgenic strawberry plants. Although long-term subcultured transgenic strawberry plants showed a phenomenon to escape the transgene, the transformation system established in this study provides new opportunities for genetic improvement of strawberry plants.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.118-123
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• 2015

Metagenomics is a powerful tool to isolate novel biocatalyst and biomolecules directly from the environmental DNA libraries. Since the metagenomics approach bypasses cultivation of microorganisms, un-cultured microorganisms that are majority of exists can be the richest reservoir for natural products discovery. To discover novel herbicidal substances from soil metagenome, we established three easy, simple and effective high throughput screening methods such as cucumber cotyledon leaf disc assay, microalgae assay and seed germination assay. Employing the methods, we isolated two active single clones (9-G1 and 9-G12) expressing herbicidal activity which whitened leaf discs, inhibited growth of microalgae and inhibited root growth of germinated Arabidopsis seeds. Spraying butanol fraction of the isolated active clones' culture broth led to growth retardation or desiccation of Digitalia sanguinalis (L) Scop. in vivo. These results represent that the screening methods established in this study are useful to screen herbicidal substances from metagenome libraries. Further identifying molecular structure of the herbicidal active substances and analyzing gene clusters encoding synthesis systems for the active substances are in progress.

• Journal of Plant Biotechnology
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• v.35 no.4
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• pp.291-298
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• 2008

Methylmercury, an organic derivative, is the principal form of mercury that biomagnifies and causes neurodegenerative symptoms in animals. In recent years, living modified organism (LMO) resulting from biotechnology has played a highly visible and controversial role. Despite the potential benefits of this technology, public concerns have been raised about the environmental risk of LMO. The concern on the risk from LMO release has urged efforts to evaluate and manage the risks of the LMO. To build up the capacity building of risk assessment method for LMO used environmental remediation, we engineered Solanum nigrum L, expressing the modified bacterial gene, merB, encoding organomercurial lyase. Two independently isolated transgenic lines produced merB RNA. Transgenic Solanum nigrum leaf discs expressing merB gene showed organic mercury resistance, forming shoots well on growth medium containing $0.5{\mu}M$ methylmercury (II) chloride and $1{\mu}M$ phenylmercuric acetate while control plants breached. Transgenic merB seeds germinated and grew on growth medium containing $2{\mu}M$ methylmercury (II) chloride and phenylmercuric acetate. The merB transgenic plants will be used for risk assessment of natural environment.