• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.1
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• pp.37-48
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• 1998

Effect of plant hormones on the leaf senescence of mung bean (Phaseolus radiatus) was investigated by measuring the changes of reducing sugar contents and invertase isozyme activities in detached leaves treated with NAA, $GA_3$ or BA. During dark-induced senescence, reducing sugar contents in the detached leaves increased temporarily at 4 d, thereafter decreased rapidly and reached minimum values within 7-14 d. The pattern of soluble acid invertase activity in the senescing leaves kept in the dark was similar to that of reducing sugar accumulation, whereas the activities of alkaline and extracellular invertases were not significantly changed during leaf senescence. Therefore, these results suggest that soluble acid invertase, but not alkaline and extracellular invertases, induces the accumulation of reducing sugar during leaf senescence of mung bean plants. Exogenous NAA application had little or no effect in the increase of soluble acid invertase activity during dark-induced senescence compared to the control. However, exogenous applications of $GA_3$ and BA led to the increase of soluble acid invertase activity in the senescing leaves. Particularly, BA application was very effective in enhancing the activity of soluble acid invertase as well as in delaying chlorophyll breakdown during dark-induced senescence. These results suggest, therefore, that BA regulates the activity of soluble acid invertase, which leads to the accumulation of reducing sugar, and the stability of photosynthetic apparatus to delay leaf senescence.

• Korean Journal of Microbiology
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• v.29 no.6
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• pp.408-415
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• 1991

TOL plsmid size of Flavobacterium odoratum SUB53 was estimated as 83 Md and the optimum concentration of m-toluate degradation by TOL plasmid was 5 mM. $H_{2}$ production by Rhodopseudomonas sphaeroides KCTC1425 was largely dependent on nitrogenase activity and showed the highest at 30 mM malate with 7 mM glutamate as nitrogen source. Nitrogenase activities were inhibited by 0.3 mM $NH_{4}^{+}$ions, to be appeared the decrease of $H_{2}$ production. Conjugation of TOL plasmids from F. odoratum SUB53 and Pseudomonas putida mt-2 to R. sphaeroides showed the optimum at the exponential stage of recipient cells in presence of helper plasmid pRK2013. According to the investigation of catechol-1,2-oxygenase (C-1, 2-O) and catechol-2,3-oxygenase (C-2,3-O) activities of R. sphaeroides C1 (TOL SUB53) and C2 (TOL mt-2), the gene for C-2,3-O is located on TOL plasmid and gene for C-1, 2-O on the chromosome of R. sphaeroides. m-Toluate was biodegraded by TOL plasmid in R. sphaeroides C1 and C2, presumably to be produced $H_{2}$ gas from the secondary metabolites of m-toluate.e.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.37-48
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• 1993

Effect of plant hormones on the leaf senescence of mung bean (Phseoln radiatus) was investigated by measuring the changes of reducing sugar contents and invertase isozyme activities in detached leaves treated with NAA, $GA_3$ or BA. During dark-induced senescence, reducing sugar contents in the detached leaves increased temporarily at 4 6, thereafter decreased rapidly and reached minimum values within 7-14 6. The pattern of soluble acid invertase activity in the senescing leaves kept in the dark was similar to that of reducing sugar accumulation, whereas the activities of alkaline and extracellular invertases were not significantly changed during leaf senescence. Therefore, these results suggest that soluble acid invertase, but not alkaline and extracellular invertases, induces the accumulation of reducing sugar during leaf senescence of Rung bean plants. Exogenous NAA application had little or no effect In the increase of soluble acid invertase activity during dark-induced senescence compared to the control. However, exogenous applications of $GA_3$ and BA led to the increase of soluble acid invertase activity in the senescing leaves. Particularly, BA application was very effective In enhancing the activity of soluble acid invertase as well as in delaying chlorophyll breakdown during dark-induced senescence. These results suggest, therefore, that BA regulates the activity of soluble acid invertase, which leads to the accumulation of reducing sugar, and the stability of photosynthetic apparatus to delay leaf senescence.

• Journal of Photoscience
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• v.3 no.1
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• pp.9-14
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• 1996

For three cultivars of chilling-sensitive cucumber plants, chilling sensitivity was evaluated in terms of photosynthetic activity using Chl fluorescence techniques. Low-temperature treatment caused a decrease in photosynthetic activities of cucumber leaves, measured as CO$_2$ exchange, as well as the decrease in the stomatal conductance. FR of the three cultivars decreased after chilling for 24 h in light and the extent of decline of F$_R$ was the greatest in 'Chosaeng' cultivar. When these plants were recovered from light-chilling, 'Chosaeng' and 'Samchuk' cultivars did not fully restore the original value of F$_R$ after 24 h of recovery, in contrast to 'Ilmi' cultivar which showed a rather efficient recovery. The results of FR study showed that 'Chosaeng' was most susceptible, whereas Ilmi was most resistant, to chilling among the three cultivars of cucumber plants. When quenching coefficients for chlorophyll fluorescence was analyzed after chilling the cucumber plants for 24 h in light, 'Chosaeng' elicited more rapid declines in the coefficients for photochemical quenching (qQ), non-photochemical quenching (qNP) and energy-dependent quenching (qE) than 'Ilmi' and 'Samchuk'. The implications of these observations are discussed in relation to the growth habits of the respective cultivars in the field. The results showed that measurement of chlorophyll fluorescence was an effective means of screening chilling tolerance of cucumber plants. Furthermore, the study on the chlorophyll fluorescence induction and fluorescence quenching charactersitics showed that low temperature could accelerate inhibition of photosynthesis in chilling-sensitive plants, by limiting Calvin cycle activity and disrupting, in part, the energy dissipation mechanims of the photosystem II.

• Molecules and Cells
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• v.27 no.6
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• pp.641-649
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• 2009

Pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) catalyzes the reversible interconversion of fructose-6-phosphate and fructose-1,6-bisphosphate, a key step in the regulation of the metabolic flux toward glycolysis or gluconeogenesis. To examine the role of PFP in plant growth, we have generated transgenic Arabidopsis plants that either overexpress or repress Arabidopsis PFP subunit genes. The overexpressing lines displayed increased PFP activity and slightly faster growth relative to wild type plants, although their photosynthetic activities and the levels of metabolites appeared not to have significantly changed. In contrast, the RNAi lines showed significantly retarded growth in parallel with the reduced PFP activity. Analysis of photosynthetic activity revealed that the growth retardation phenotype of the RNAi lines was accompanied by the reduced rates of $CO_2$ assimilation. Microarray analysis of our transgenic plants further revealed that the altered expression of $AtPFP{\beta}$ affects the expression of several genes involved in diverse physiological processes. Our current data thus suggest that PFP is important in carbohydrate metabolism and other cellular processes.

• Applied Biological Chemistry
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• v.41 no.4
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• pp.228-234
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• 1998

An adaptive measure of photosynthetic cells to a condition identified with a reduction of cellular energy charge, caused by water deficit-induced impairment of photosynthetic ATP production, was investigated using hydroponically cultured rice seedlings. Water stress treatment of the seedlings resulted in a marked decrease in cellular ATP level, a significant increase in the content of NAD(H) and concurrent decrease in that of NADP(H) in shoots, which accompanied a decrease in the activity of NAD kinase (EC 2.7.1.23) that specifically converts NAD(H) to NADP(H). The decline in the enzyme activity was particularly evident in the $Ca^{2+}/calmodulin-dependent$ kinase, the major form of NAD kinase in plants, whereas the level of active calmodulin remained unchanged during water deficit. The ratio of $NADP^+$ to NADPH was maintained nearly constant and no increases were seen in the level of $H_2O_2$ and the activities of $superoxide/H_2O_2-detoxifying$ enzymes in shoots stress-treated for two days. Based on these results, it may be suggested that rice plants take a strategy to cope with an adverse situation of limited photophosphorylation created by water deficit in that cells facilitate ATP production through glycolysis and oxidative phosphorylation; in doing so, rice cells suppress NAD kinase activity, consequently up-sizing the NAD(H) pool at the expense of the NADP(H) pool. Several parameters associated with the stress symptoms are also of implicative that there is no overproduction of superoxide radical or the related active oxygen at least in rice seedlings.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.35-42
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• 1998

We compared absorption and adsorption rates of air pollutants by plants to eveluate the difference of absorption capacity of plant species and kinds of air pollutants, when foilage plants were exposed to $O_3$ and $SO_2$ singly and combiningly. Absorption and adsorption rates of three foliage plants exposed to $O_3$ and $SO_2$ singly and in combination varied a little according to plant species and kinds of air pollutants. But total absorption rate of Spathiphyllum patinii and Ficus benjamina was higher, and it was lower in Pachira aquatica. When exposed to $O_3$ and $SO_2$ at the same concentration, Pachira aquatica absorbed more $O_3$ than $SO_2$, in contrast to Ficus benjamina absorbing more $SO_2$. On the other hand, Spathiphyllum patinii absorbed as much $O_3$ as $SO_2$. Physiological activities were measured since absorption rates were affected by physiological characteristics of plants. Spathiphyllum patinii and Ficus benjamina showed higher photosynthetic and transpiration rates, and Pachira aquatica showed lower values. And diffusive and stomatal resistences of Pachira aquatica were higher than those of two other species. These results showed that absorption capacity was affected by the differences of physiological characteristics. Absorption capacity of air pollutants increased in plants, such as Spathiphyllum patinii and Ficus benjamina, which had high $SO_2$ absorption rate. We found that plants showing high $CO_2$ absorption rates absorb a lot of air pollutnats.

• Korean Journal of Medicinal Crop Science
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• v.20 no.3
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• pp.171-176
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• 2012

This study was conducted to investigate the effect of atmosphere-leaf vapor pressure deficit (VPD) in Allium microdictyon Prokh. and Allium ochotense Prokh. The vapor pressure deficit (VPD) was rapidly increased with increasing temperature and decreasing relative humidity. Taken as a whole, the stomatal transpiration reaction was slightly late with increading of VPD. Maximum photosynthetic rate at high-VPD condition was 5.98 ${\mu}mol$ $CO_2{\cdot}m^{-2}{\cdot}s^{-1}$ in Allium microdictyon, which was a little lower than 6.59 ${\mu}mol$ $CO_2{\cdot}m^{-2}{\cdot}s^{-1}$ in Allium ochotense, respectively. After 2 p.m, stomatal transpiration of Allium microdictyon at the high VPD condition were rapidly decreased. Ci/Ca began to decline sharply at 8 a.m and showed the lowest value at 2 p.m, The results showed that Ci/Ca decreased with being used $CO_2$ in the mesophyll intercellular space for photosynthesis. In high VPD condition, The water potential values showed the highest at 5 a.m, and the lowest at 1 p.m in high VPD condition. The water saturation deficits (WSD) in high VPD condition showed about 1.5 times higher than in low VPD condition. The results indicated that physiological activities in Allium microdictyon is more limited from high VPD conditions.

• ALGAE
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• v.29 no.4
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• pp.311-319
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• 2014

The biocide sodium hypochlorite (NaOCl) is widely used for controlling algal growth, and this application can be extended to marine environments as well. This study evaluates the biocidal efficiency and cellular toxicity of NaOCl on the harmful dinoflagellate Cochlodinium polykrikoides, with emphasis on pigment production and antioxidant enzyme activity. The test organism showed dose-dependent decrease in growth rate on exposure to NaOCl, and the 72 h $EC_{50}$ was measured to be $0.584mg\;L^{-1}$. NaOCl significantly decreased pigment levels and chlorophyll autofluorescence intensity, indicating possible detrimental effects on the photosystem of C. polykrikoides. Moreover, it significantly increased the activities of antioxidant enzymes, suggesting the production of reactive oxygen species in the cells. These data indicate that NaOCl exerted deleterious effects on the photosynthetic machinery and induced oxidative damage in the dinoflagellate and this biocide could be effectively used for the control of algal blooms.

• Journal of Plant Biology
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• v.33 no.4
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• pp.277-283
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• 1990

Inactivation and reactivation of photosynthetic oxygen evolving complex were studied with isolated spinach (Spinacia oleraceda. L.) photosystem II particles by the activity of oxygen evolution and chlorophyll fluorescence. When the particles were treated with Tris and urea, the oxygen evolution was inactivated and three polypeptides having molecular weights of 33 kDa, 24 kDa and 18 kDa were simultaneously released. But in NaCl-treated particles, two polypeptides of 24 kDa and 18 kDa were removed from PS II particles. The oxygen evolution activities of Tris and urea-treated particles were not restored by adding cation ions (Mg2+, Mn2+ and Ca2+), but the NaCl-treated particles were restored by exogenously added Ca2+. The removal of these extrinsic polypeptides, especially 33 kDa, markedly showed the decrease of the variable fluorescence (Fv). These results are likely to be due to dissipate thermal energy by antenna of photosystem II complexes.