• BMB Reports
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• v.41 no.1
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• pp.79-85
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• 2008

The source of nitric oxide (NO) in plants is unclear and it has been reported NO can be produced by nitric oxide synthase (NOS) like enzymes and by nitrate reductase (NR). Here we used wild-type, Atnos1 mutant and nia1, nia2 NR-deficient mutant plants of Arabidopsis thaliana to investigate the potential source of NO production in response to Verticillium dahliae toxins (VD-toxins). The results revealed that NO production is much higher in wild-type and Atnos1 mutant than in nia1, nia2 NR-deficient mutants. The NR inhibitor had a significant effect on VD-toxins-induced NO production; whereas NOS inhibitor had a slight effect. NR activity was significantly implicated in NO production. The results indicated that as NO was induced in response to VD-toxins in Arabidopsis, the major source was the NR pathway. The production of NOS-system appeared to be secondary.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.153-161
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• 2007

Field experiments were conducted to determine the physiological and biochemical basis of the interactive effect of sulphur (S) and nitrogen (N) application on seed and xanthotoxin yield of Ammi majus L. Six treatments were tested ($T_1$ = control-without manure and fertilizers, $T_2$ = manure @ 9 kg $plot^{-1}-10\;t\;ha^{-1},\;T_3=A_0N_{50}K_{25}P_{25},\;T_4=S_{40}N_{50}K_{25}P_{25},\;T_5=S_{40}N_{100}K_{25}P_{25}\;T_6=S_{20+20}N_{50+50}K_{25}P_{25})$). Nitrate reductase (NR) activity and ATP-sulphurylase activity in the leaves were measured at various phonological stages, as the two enzymes catalyze rate-limiting steps of the assimilatory pathways of nitrate and sulphate, respectively. The activities of these two enzymes were strongly correlated with seed and xanthotoxin yield. The highest nitrate reductase activity, ATP-sulphurylase activity and xanthotoxin yield were achieved with the treatment $T_4$. Any variation from this treatment decreased the activity of these enzymes, resulting in a reduction of the seed and xanthotoxin yield in Ammi majus L. The higher seed and xanthotoxin yield achieved in Ammi majus L. at treatment $T_4$ could be due to optimization of leaf soluble protein and photosynthetic rate, as these parameters are Influenced by S and N assimilation.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.255-259
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• 1992

The effect of nitrate, nitrite and ammonia as inorganic nitrogen sources on the modulation of nitrogen metabolism of Botryococcus braunii UTEX.-572 has been studied under aeration. The primary process in the regulation of nitrogen metabolism by this alga has the nitrate uptake system. This uptake of nitrate operation was immediately inhibited by the presence of 0.5 mM of ammonium and reversed by 0.2∼0.3 mM ammonium. When cell were exposed to 5 mM of ammonium for 24 hours the activity of nitrate reductase became inactive.

• KSBB Journal
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• v.5 no.2
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• pp.151-158
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• 1990

Investigations on the liability of nitrogen usuage by Nostoc muscorum that has nitrogen fixing ability, and cultured tobacco cells as they were associately cultured on nitrogen-free media and effects of polyamine on the associated culture condition were carried out. In addition, measurement on the activity of nitrate reductase, glutamine synthetase, glutamate dehydrogenase and glutamate synthase that take part in the metabolic pathway of nitrogen fixation product were performed. Among enzymes participating in the metabolic pathway of nitrogen fixation products, the activity of nitrogen reductase stimulated five times in associated culture, and that of glutamine synthetase of N. muscorum increased two times after heterocyst differentiated. Activity of glutamate dehydrogenase increased markedly when cultured tobacco cells were solely incubated on nitrogen-free media, but inhibited when cultured associately. And, glutamate synthase was showed the highest activity in 0.1 mM of spermine treated group.

• Journal of the korean society of oceanography
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• v.34 no.1
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• pp.49-57
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• 1999

A red tide organism, Amphidinium carterae was incubated under different iron/chelator and nitrate concentrations to investigate the factors controlling the growth. The chelation capacity played a critical role in regulating the nitrate reductase (NR) activity and in vivo fluorescence of this organism. However, there was a significant difference between the NR activity and in vivo fluorescence in response to trace metals and chelator treatments. In vivo fluorescence was the highest in FeEDTA 10 ${\mu}$M treatments and the lowest in DTPA 10 ${\mu}$M treatments. This indicates that the availability of the trace metal is important in regulating the in vivo fluorescence of this photosynthetic microalgae In contrast, NR activity showed the highest values in trace metal enriched treatments, and trace metal + DTPA treatments showed fairly high NR activities. This suggests that DTPA treatment did not hinder the NR activity as much as it did in vivo fluorescence. In vivo fluorescence and NR activity increased with nitrate concentration of up to 50 ${\mu}$M and remained relatively constant or the rate of increase decreased above that concentration, indicating that initial nitrate concentration of higher than a certain level would not accelerate the growth of A. carterae. Further investigation is needed to elucidate the reason for the difference in timing sequence between the NR and in vivo fluorescence in response to different metal treatments and chelation capacity.

• Journal of the Korean Society of Tobacco Science
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• v.4 no.1
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• pp.1-5
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• 1982

The metabolic enzymes, nitrate reductase, amylase and peroxidase and the Photorespiratory enzyme, Slycolate oxidise in Nicotiana tabacum varieties were studied at various growth stages. The enzyme activities of young leaves with rapid growth were different from those of old ones with stationary growth. In young leaves, activity of nitrate reductase was higher than that in mature ones and amylase activity was fairly constant in all stages. Activities of glycolate oxidise and peroxidase were found to be significantly lower in young leaves than in mature ones. Activity of glycolate oxidase in mature middle leaves was 2.45 times higher than that of young ones and inhibited by 36% when the enzyme was treated with 0.16 mM isonicotinic hydrazide.

• Proceedings of the Korean Society of Crop Science Conference
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• 1991.10a
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• pp.32-33
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• 1991

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.298-302
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• 2006

A number of field experiments were conducted to assess the role of combined application of nitrogen and sulfur to increase the seed and oil yield of nonnodulating soybean (Glycine max (L) Merr.) cv. PK-416 $(V_1)$ and cv. PK-1024 $(V_2)$. Six combinations of N and S in three replicates each were used for this purpose i.e. $0\;S+23.5kg\;N\;ha^{-1}(T_1);\;0\;S+23.5+20kg\;N \;ha^{-1}(T_2);\;40\;S+23.5kg\;N\;ha^{-1}(T_3);\;40\;S+23.5+20kg\;N\;ha^{-1}(T_4);\;20+20\;S+23.5kg\;N\;ha^{-1}(T_5);\;20+20\;S+23.5+20kg\;N\;ha^l(T_6)$. Nitrate reductase (NR) and ATP-sulphurylase activities in the leaves were measured at various growth stages as the two enzymes catalyze the rate limiting steps of the assimilatory pathways of nitrate and sulphate, respectively. The activities of these enzymes were strongly correlated with seed yield. The higher seed, oil and protein yields were achieved with the treatment $T_6$ in both the cultivars due to optimization of NR activity and ATP-sulphurylase activity, as these parameters were influenced by N and S assimilation. Any variation from this combination was observed to decrease the activity of these enzymes resulting in reductions in the seed, oil and protein yield of soybean.

• Applied Biological Chemistry
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• v.44 no.4
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• pp.240-245
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• 2001

Suppression of nitrate accumulation in vegetables through foliar application of micronutrients was investigated. Spinach and lettuce were grown in pots under greenhouse condition. Micronutrient solutions containing Cu, Mn, Mo, and Zn were used; chitosan was added into one and the other contained chitosan oligomers. The micronutrient solutions were sprayed on the leaves at 3 and 4 weeks after transplanting of 20-day-old seedlings. Plants were harvested at 5-weeks after transplanting. Yield, contents of chlorophyll, Brix value, micronutrient, and nitrate, and nitrate reductase activity were measured. Fresh weights of lettuce and spinach were significantly increased by the foliar application of micronutrients. Contents of chlorophyll and micronutrients were higher in micronutrient-treated plants, while those of nitrate were reduced by about 10 and 14-23% in lettuce and spinach, respectively. Compared to the control plants, nitrate reductase activity was higher in plants treated with micronutrients. Results of this study indicate the effect of micronutrients on the suppression of nitrate accumulation was relatively small in comparison to the contents of nitrate in leaves of spinach and lettuce. To maximize the effect, nutrient composition in solution, application time, and frequency should be further examined, taking into consideration nitrogen level in soil and other environmental factors including light condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.60-65
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• 1982

In order to observe the degree and response of drought-resistance and its physiological mechanism in barley and wheat seedling stage, 5 species (16 cultivars) were tested for the changes of nitrate reductase and protease activity and the accumulation of free proline, by being subjected to water stress by withholding watering for 8 days at 10 days (at the 3rd leaf stage) after emergence and by imposing water stress to the excised first leaf by polyethyleneglycol solution (osmotic potential, -20 bars) for 48 hours. The average rate of decrease of all cultivars was 42% in nitrate reductase activity and 73% in protease activity. But proline content in water stress was increased 10 folds more than that of control. The decrease4 rate of nitrate reductase activity in 5 species was in the order of wheat < rye < covered barley < naked barley < two-row barley: wheat being the lowest. The decreased rate of protease activity in 5 species was in the order of wheat > rye > two-row barley > covered barley > naked barley: wheat being the" heighest. The accumulated amount of free proline in 5 species by water stress was in the order of wheat > covered barley > rye > naked barley > two-row barley. And the increased ratio (folds) of free proline of water stress to control was in the order of rye(13) > wheat. covered barley(11) > naked barley(99) > two-row barley(7): rye being the highest. In terms of the enzymatic activity and the physiotically adaptive metabolism during the processing leading to drought-resistance, the degree of drought-resistance of 5 species to water stress at seedling stage was shown to be in the order of wheat > rye > covered barley > naked barley > two-row barley.