• Journal of Plant Biology
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• v.25 no.3
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• pp.105-111
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• 1982

These studies were undertaken to elucidate the reasons for the low productivity of ginseng by comparing the rate of $CO_2$-fixation and photorespiration, variation in the amounts of intermediates and enzyme activities of glycolate oxidase and catalase in ginseng with those of potato. The ability of $CO_2$-fixation in ginseng was found to be one half of that of potato and there were significant differences between those two plants in the rate of $^{14}C$ incorporated into glutamate, aspartate, malate and 3-PGA, but little differences in P-glycolate, glycolate, serine and glycine. The ratio of photorespiration to dark respiration and the activities of glycolate oxidase and catalase in the two species were about same, but ginseng showed higher ratio in photorespiration to total $CO_2$-fixation than potato did. These results indicated that the low productivity of ginseng may resulted from the low $CO_2$-fixation ability and high rate of photorespiration.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.267-274
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• 2018

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.

• Journal of Plant Biology
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• v.33 no.3
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• pp.203-210
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• 1990

Effects of blue and red light on photorespiration in the leaf disks of pea were studied. The rate of total 14CO2 fixation was more or less higher under red light than blue light irradiation of the same quantum (94.8 $\mu$Em-2.S-1/mV). The release of 14CO2 by photorespiration was more stimulated under blue than red light. Among the photorespiratory intermediates, 14C was more incorporated ito serine under blue light than red light. However, 14C was more incorporated into glycine under red light than blue light. The incorporation of 14C into glycolate was very low under both light qualities, but higher under red light than blue light. Among the enzymes related to photorespiration, only glycolate oxidase was activated and/or synthesized by blue light irradiation. Moreover, more 14C2 was released from glycoate-1-14C under blue light than red light irradiation, but 14C2 release from glyoxylate-1-14C and glycine-1-14C showed no difference by the either light qualities. These results suggest that blue light is more effective in the photorespiratory CO2 evolution than red light. The reason is considered that glycolate is easily metabolized under blue light due to the stimulation of the glycolate oxidase activity.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.46-50
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• 1984

Four rice cultivars (two japonicas and two japonica x indica hybrids) were grown in the hydroponic medium in order to investigate the photorespiration rate and ribulose-1, 5-bisphorphate carboxylase (EC 4, 1, 1;39) activity. The results were as follows: 1. Photorespiration rate was increased by the increasing light intensity as well as photosynthesis until light saturation point. Hangangchalbyeo of a hybrid variety had higher photorespiration rate than two japonicas(Jiniubyeo and Seolakbyeo) and one hybrid(Nampungbyeo) tested at ear formation stage. 2. Ribulose-1, 5-bisphosphate carborylase of hybrids were very sensitive to temperature showing lower activities at low temperature and much higher activities at high temperature than that of japonicas.

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.10a
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• pp.15-15
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• 2021

• Journal of Plant Biology
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• v.31 no.3
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• pp.197-203
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• 1988

The rates of photorespiration and total CO2 fixation depending on leaf ages of spinach (Spinacia oleracea L.) were investigated. Metabolic rates of glycolate and glyoxylate in isolated peroxisomes were also measured. The rate of photorespiration and total CO2 fixation ability increased with the maturing of leaf, but decreased with senescence. Activities of enzymes involved in the peroxisomal photorespiratory pathway such as catalase, glycolate oxidase, NADH-glyoxylate reductase and glutamate-glyoxylate transaminase were highest in the mature leaf, but also decreased with aging of leaf. Glutamate-glyxolate transaminase activity significantly decreased with senescence, especially. the metabolic rate of glycolate was observed to be lower than that of glyoxylate in isolated peroxisomes. Glycolate seemed to be metabolized mainly to glycine, however, it also oxidized to CO2 when glycolate was supplied as a substrate for glycine synthesis instead of glyoxylate. The conversion rates of glycolate and glyxylate into CO2 increased with the senescence of leaves.

• Journal of Plant Biology
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• v.27 no.4
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• pp.253-261
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• 1984

Leaf discs isolated from the pea seedling grown in nutrient solution containing 5mM ammonia or nitrate exhibited a half level of photorespiration as compared with the nitrogen free control. The manifestation of the ammonia effect appeared somewhat earlier than that of nitrate effect, but this difference subsided as the culture periods was extended. The total amount of ${CO}_2$ fixed by leaves from nitrogen-supplemented seedlings showed approximately 1.5 fold increase over the control with the ammonia effect being manifested earlier than the nitrate effect. The activities of peroxisomal serine: glyoxylate aminotransferase were always higher with ammonia than nitrate, the two types of nitrogen source, however, had similar effect on conversion rate of glyoxylate into glycine. These results indicate that exogenous ammonia does not act directly as an effector of this aminotransferase in vivo. But changes in the level of the pool size of glycine and serine, both of which are the intermediates of photorespiratory process, suggest that exogenous ammonia inhibit the transformation of serine from glycine metabolically.

• Journal of Applied Biological Chemistry
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• v.44 no.4
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• pp.159-162
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• 2001

Plant stress incurred by flooding was studied in terms of oxidative stress, using greened rice seedlings subjected to a complete submergence followed by re-exposure to air under illumination ($30W/m^2$). It appeared that shoot tissues of the seedlings suffered oxygen deficiency during the flooding treatment, pertinent to the general concept. Interestingly enough, however, membrane peroxidation in shoots was enhanced by the submergence, as assessed by the content of 2-thiobarbituric acid-reactive substances (TBARS), and the re-aeration resulted in a rapid reduction of TBARS content. Such pattern of response was also seen in the change in the steady state level of $H_2O_2$. In contrast, superoxide dismutase and glutathione reductase that are involved in the detoxifying processes of superoxide in plant cells were significantly activated only during the re-aeration. These results allowed us to suggest the followings as a working hypothesis. Photorespiration-linked production of $H_2O_2$ may largely contribute to the increase in $H_2O_2$ level as well as TBARS production in shoots during the submergence. An abrupt re-supply of $CO_2$ by the re-aeration brings the photosynthetic apparatus back to full operation, suppressing photorespiration and probably causing a momentary, excess formation of superoxide and its dismutation product through side reaction, which gives rise to activating substrate-inducible antioxidative enzymes.

• BMB Reports
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• v.28 no.3
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• pp.271-274
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• 1995

Glycolate oxidase is one of the key enzymes in the pathway of photorespiration. In this study we investigated the effects of light on the expression of the spinach glycolate oxidase gene. Continuous exposure to white light resulted in a gradual increase in the steady-state level of glycolate oxidase mRNA within a time period of 2~24 h in both etiolated and dark-adapted green seedlings. A short white light pulse also increased the level of glycolate oxidase mRNA in etiolated seedlings. The mRNA level reached a maximum at 6~8 h after the pulse and decreased by 24 h after the pulse. The induction patterns of the glycolate oxidase gene by white light appeared similar to those of the rbcS gene, indicating that a common or coordinating regulatory system may be involved in the expression of the glycolate oxidase and rbcS genes. A red light pulse induced an increase in the amount of glycolate oxidase mRNA and this effect was reversed by a subsequent far-red light pulse, suggesting that the expression of the glycolate oxidase gene is regulated by phytochrome.

• 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.