• Asian-Australasian Journal of Animal Sciences
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• v.21 no.5
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• pp.657-662
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• 2008

To develop transgenic orchardgrass (Dactylis glomerata L.) resistant to high temperature, the recombinant DgHSP17.2 gene was introduced into orchardgrass plants using the Agrobacterium-mediated transformation method and expressed constitutively under the control of the CaMV 35S promoter. The results of genomic DNA PCR and Southern analysis showed a DNA band and hybridization signal on agarose gel and X-ray film in transgenic orchardgrass plants harboring the recombinant DgHSP17.2 gene, but a DNA band and hybridization signal were not observed in the wild type and empty vector control plants. The same result was also obtained in RT-PCR and Southern blot analysis, and these transgenic orchardgrass plants did not show any morphological aberration both in the culture bottle and soil mixture. When leaf discs cut from transgenic orchardgrass plants with recombinant DgHsp17.2 gene were exposed to lethal temperature (heat treatment at $60^{\circ}C$ for 50 min), 60-80% of the leaf discs showed only damage symptoms, but non-transgenic leaf discs showed a lethal condition. These results indicate that the DgHsp17.2 gene may act as a protector from heat stress in plants.

• Journal of Ginseng Research
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• v.13 no.1
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• pp.98-104
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• 1989

In order to determine the specific active oxygen species directly related to chlorophyll bleaching in the leaf-burning disease, we investigated the effects of singlet oxygen (1O2), superoxide radical (O2-), and hydrogen Peroxide (H2O2) on isolated chloroplast suspension and leaf discs from Panax ginseng C.A. Meyer. When the singlet oxygen was added to the chloroplast suspension, the chlorophyll and carotenoid contents were decreased by more than 809), similar to treatment with high light intensity (100 KLux). We assumed that the conversion of dioxygen (O2) produced either in photolysis or in breakdown of hydrogen peroxide to singlet oxygen resulted from photorespiration. On the basis of these experiments , :he inhibitory effects of active oxygen scavengers propylgallic acid (PGA), 2,5-ditetrabutyl hydroquinon (DBH), sodium pyrosulfate (SPS), and ascorbic acid (ABS) were examined. In chloroplast suspension all four scavengers inhibited chlorophyll bleaching by more than 75fl , and in the leaf discs the inhibition rates of SPS, PGA and ABS were 46%, 51%, and 96% respectively.

• Journal of Photoscience
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• v.3 no.1
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• pp.15-21
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• 1996

To investigate the chilling sensitivity related injuries in the photosynthetic apparatus of cucumber leaves, the light-chilling induced alterations of chlorophyll fluorescence transients in cucumber leaves were compared with those in pea leaves. As an early effect of light-chilling, an increase in Fp/Fm$^*$ was observed in both pea and cucumber leaves, which was saturated by about 6 h chilling. However, the saturated value of Fp/Fm was almost 1.0 in cucumber, in contrast to about 0.8 in pea. During the recovery period after 24 h chilling, the light-chilling induced changes in pea seemed to be reversed, but those in cucumber leaves were thought to be irreversible, because Fo was increased significantly. Light-chilling caused significant decreases in qQ and qE in cucumber leaves, but qR was increased until 6 h, and decreased thereafter. In both pea and cucumber leaves, Fm was increased by 2 h dark treatment. The Fm from the predarkened pea leaf discs was higher than the value from the preilluminated ones during the whole period of light-chilling (500 $\mu$mol m$^{-2}$s$^{-1}$ PAR). However, the predarkened cucumber leaf discs showed a reduction in Fm and an increase in Fo during the 2 h chilling in the light. These results indicate that the causes of chilling sensitivities in photosynthetic apparatus of cucumber leaves are possibly related with the damage in PSI reaction center and the ability of acidification of lumen by PSII.

• Journal of Plant Biology
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• v.31 no.4
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• pp.277-288
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• 1988

The effects of ammonium ion and glutamate on CO2 fixation abilities and related carbon metabolism were investigated in pea (Pisum sativum L. cv. Sparkle) leaf discs under conditions favoring photorespiration (21% O2, 0.03% CO2) and nonphotorespiration (5% O2, 0.03% CO2). A concentration of more than 10 mM of NH4+ decreased the photosynthetic CO2 fixation and those inhibitory effects were more remarkable in 21% O2 than in 5% O2 conditions. The effect of glutamate on CO2 fixation was found to be independent of the O2 level, as glutamate increased the CO2 fixation under both 21% and 5% O2 conditions. L-methionine-dl-sulfoximine, an irreversible inhibitor of glutamate synthetase, however, inhibited the CO2 fixation markedly under 21% O2, but did not affect it under 5% O2 conditions. The treatment with NH4+ elevated the relative amounts of 14C incorporated into soluble components from 14CO2 with no relation to O2 levels, while glutamate increased 14C into insoluble components and neutral sugars. Glutamate, especially, seemed to stmulate the biosynthesis of starch under 5% O2 condition. These results indicated that NH4+ stimulated the degradation of sugar or starch and this proposal was confirmed by the increasing of pyruvate kinase activity in leaf discs treated with ammonium ion.

• Journal of Plant Biotechnology
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• v.30 no.4
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• pp.405-410
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• 2003

Environmental stress is the major limiting factor in plant productivity. In order to evaluate the stress tolerance of potato plants, leaf discs of two potato cultivars, Atlantic and Superior, were subjected to various stress conditions of high temperature, methyl viologen, H2O2, or $H_2O$$_2$. When potato leaf discs were exposed to high temperature at 37$^{\circ}C$ for 84 hr, Atlantic plants, a cultivar with high sensitivity to heat stress, showed about 20％ higher membrane damage than Superior plants. When exposed to 2$\mu$M methyl violgen (MV), a superoxide generating non-selective herbicide, for 36 hr, Atlantic plants also showed about 38％ higher membrane damage than Superior plants, and were more susceptible up to 10$\mu$M MV concentration tested. On treatment with 0.75M NaCl, Atlantic plants also had about 45％ less chlorophyll contents in leaf discs than Superior plants. There was, however, no difference in chlorophyll content of two cultivars at higher NaCl concentrations. The effect of $H_2O$$_2$ on the two cultivars was mixed. At low $H_2O$$_2$ concentration (25 mM) , Superior plants were more susceptible to $H_2O$$_2$stress after 36 hr. However, at high $H_2O$$_2$ concentration (100 mM), Atlantic plants exhibited higher susceptibility after 36 hr. The results indicate that in vitro leaf discs reflecting the whole plants in this study will be useful for selection and characterization of elite transgenic potato plants with enhanced tolerance to environmental stress.

• Journal of Environmental Science International
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• v.15 no.12
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• pp.1109-1117
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• 2006

To investigate the influence of the mesophyll cells on stomatal opening in response to white light, the segments of isolated epidermis were transferred on partly exposed mesophyll cells of a leaf and stomatal apertures were measured. Transferring the isolated epidermis on partly exposed mesophyll cells of a leaf caused a marked increase on stomatal apertures while stomata in isolated epidermis incubated in MES buffer hardly opened. Mesophyll infiltration with photosynthetic inhibitors (DCMU, DCCD, $NaN_3$) was performed to elucidate the correlation between stomatal apertures and the degree of photosynthetic activity. It was found that transferring the isolated epidermis on partly exposed mesophyll cells of a leaf caused an increase of stomatal apertures depending on the degree of photosynthetic activities. In $NaN_3$ infiltrated leaf discs, transferring the fresh isolated epidermis on partly exposed mesophyll cells of a leaf showed no significant effect, but a slight increase on stomatal apertures. Isolated epidermis alone did not respond to the light properly, but if it was closely contacted with mesophyil cells, the stomata regained the ability of the light response. Therefore, it could be suggested that stomatai apertures were related with the degree of photosynthetic activity in the mesophyll cells.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.176-181
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• 1988

This experiment was conducted to investigate the effect of plant hormones on the time-dependent changes of photosynthesis by oxygen electrode system (Rank Brothers Inc. England) and chlorophyll contents in rice(Oryza sativa L. cv. Nihonbare) leaf discs. IAA showed no significant effect when treateds at lower concentration, however IAA 20ppm inhibited slightly the photosynthesis of leaf discs. BA increased strongly the photosynthesis with time. As the BA concentration increased, photosynthesis was significantly stimulated. $GA_3$ showed with little effect at lower concentration, however $GA_3$ 20ppm inhibited the photosynthesis. ABA inhibited strongly the photosynthesis at all the treatments. IAA, BA, and $GA_3$ stimulated chlorophyll contents, but ABA inhibited the chlorophyll contents. It can be concluded that among the plant hormones tested, BA was the most effective in stimulating photosynthesis with time and maintaining the chlorophyll contents.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.545-553
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• 1991

To find out the basic data for the possibility of agricultural utilization for GSA (Glutamine Synthetase Activity), the effect of nitrogen on the GSA in wheat leaf discs, the variation of GSA after light treatment and the comparative activity of GS during preservation were studied. The result of this study suggested that GSA could play an important and direct regulatory role in the nitrogen assimilation by wheat. During the growth stage of wheat its integral activity was found to closely match the organic nitrogen content. GS may therefore be the rate limiting enzyme in inorganic N assimilation. Moreover, integral GSA was closely correlated with grain yield and grain nitrogen. GSA could be suitable to utilize as a parameter for super type selection and an indicator for optimum nitrogen fertilization. Throughout the experiment, the contents of NO; were increased by N fertilization so that the NO; content was not attributable to change in the level of GSA. At investigation during dark-light transition of culture, no change in the level of GSA was observed until after 8-14 hours in the light treatment. And the level of GSA in wheat leaf discs during preservation at refrigerated storage $(-20^{\circ}C)$ was stable until 12 weeks, when its leaf discs were sampled with liquid nitrogen.

• Korean Journal of Weed Science
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• v.17 no.4
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• pp.390-399
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• 1997

This experiment was conducted to introduce PAT (phosphinothricin acetyltransferase, non-selective herbicide bialaphos resistant gene) gene into potato (Solanum tuberosum. cv. Desiree). Optimal shoot regeneration from leaf discs and stem segments was obtained in MS medium supplemented with 0.1 mg/L IBA and 0.5 mg/L BA, and the frequency of shoot regeneration was 54% in left discs and 46% in stem segments. In this condition, leaf discs and stem segments of potato were co-cultivated with A. tumefaciens MP90 which contained binary vector with GUS: :NPTII gene and PAT gene. Transgenic shoots were regenerated from leaf and stem-derived calli on selection medium with 100mg/L kanamycin. The 100${\mu}M$ acetosyringone treatment during the co-cultivation highly enhanced(4 times than the control) the shoot regeneration on selection medium. When the putative transgenic plants were transferred to medium with 10mg/L basta, all of them were survived. After PCR. GUS test, and Southern blot analysis of the survived plant, we confirmed that the gene was stably integrated into the potato genome and expressed. After the transgenic plants were transplanted in soil, and the transgenic plants were sprayed with the herbicide basta (300ml/10a), the transgenic plants remained green but control plants were died.

• Journal of Ginseng Research
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• v.7 no.2
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• pp.108-114
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• 1983

1. To know the site of saponin synthesis in this plant, 4-years old Panax ginseng C.A. Meyer was administered with 1, 2-l4C-acetate (Na salt, 10 ucilplant) by stem injection and was continued to grow for 3 weeks and the distribution of the radioactivity in leaf, stem and root part was identified. The percentage of radioactivity recovered was about 3.99%. 2. The sliced roots or leaf discs (2g) were bathed in the reaction mixture containing sugar, ATP, NADPH, and the distribution of the radioactivity of the fractions (sugar, saponin, sapogenin) was identified. 3. It seemed that major synthesized saponins in roots and leaves are dial and triol-type, respectively. Although both types of saponins are synthesized in roots, the main saponins seemed to be dial saponins and a significant portion of triol saponins are supplied from leaves through stem.