• Applied Biological Chemistry
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• v.45 no.3
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• pp.129-133
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• 2002

Suppression of nitrate accumulation in spinach and lettuce through foliar application of chitosan formula containing micronutrients is related with the increase of the nitrate reductase (NR) activity. If NR in spinach were highly expressed to increase the assimilatory activity, nitrate content could be reduced. For this, NR cDNA was cloned from the isolated mRNAs of spinach using reverse transcriptase-PCR. Nucleotide sequence of cloned spinach NR cDNA showed highly deduced amino acid sequence identity ($71{\sim}82%$) with other known plant NR genes. Only two nucleotide-base differences were observed in the cloned NR cDNA compared with that of the published spinach NR cDNA.

• Journal of Plant Biology
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• v.34 no.4
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• pp.283-288
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• 1991

This work was carried out to determined the effect of 2,4-dinitrophenol(DNP) on in vivo nitrate reductase activity in the root of 6 day old rye (Secale cereale L.) seedlings. The nitrate reductase activity in the roots of 6 day old rye seedlings pretreated with 0.5 mM DNP was higher than that of the control group in all the experimental conditions. The optimal concentration of KNO3 for maximum nitrate reductase activity was 10 mM in both control and treated group. The nitrate reductase activity in the treatment of 10 mM KNO3 gradually increased for 4 h in both groups, and then maintained constantly. The nitrate reductase activity occurred per hour was highest at 1 h in both groups, while it was declined by large degrees as time goes on. The daily pattern of nitrate reductase activity was gradually decreased in both groups with the passage of day. The optimal pH for this experiment and a previous paper (Kwon et al., 1991), it was determined that the nitrate reductase activity in both roots and shoots of rye seedlings was increased by the treatment of 0.5 mM DNP, and particulary in both groups, the nitrate reductase activity in the roots of rye seedlings was higher than that in shoots of them.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.112-116
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• 2002

Effects of artificial electron donors to deliver reducing power on enzymic denitrification were investigated using nitrate reductase and nitrite reductase obtained from Ochrobactrum antroyi. The activity of nitrite reductase in the soluble portion was almost the same as that in the precipitated portion of the cell extract. Nitrate removal efficiency was higher with benzyl viologen than with methyl viologen or NADH as an artificial electron donor. The turn-over numbers of nitrate and nitrite reductase were 14.1 and 1.9 umol of nitrogen reduced/min$.$mg cell extracts, respectively when benzyl viologen was used as an electron donor.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.196-200
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• 1993

A full understanding of the interdependence of leaf nitrate (($No_3$￣) metabolism and symbiotic nitrogen($N_2$) fixation in legume crops is needed to help maximize the use of both N sources as well as to improve forage quality through the inhibition of leaf nitrate accumulation. The present work examines the effects of added nitrate, the level of which are 0,2,4,8 and 12mM, on the nodule formation and leaf nitrate utilization and on the possibility of inducing nitrate-toxicity to livestocks in two alfalfa varieties, ' Vernal ' of grazing type and ' Victoria ' of hay type. Higher level of exogeneous nitrate resulted in the increased above-ground dry weight. Nodulation was inhibited severely when more than 8mM NO$_3$￣ was supplied to alfalfa plants, and leaf nitrate reductase reached a maximunm at 4mM nitrate supply. The $V_{max}$of nitrate reductase in leaves of Vernal was similar to that of Victoria, whereas the $K_m$ of Vernal was higher than that of Victoria. High accumulation of leaf nitrate, $4{\times}10^{-5}$ g/g leaf fresh weight, was shown at 12mM nitrate supply, which was thought to be not enough to induce nitrate-toxicity to livestocks.icity to livestocks.

• Asian Journal of Turfgrass Science
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• v.1 no.1
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• pp.49-55
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• 1987

Zoysia japonica를 부위별로 나누어서 그들간의 amylase와 nitrate reductase의 활성을 조사한 결과는 다음과 같다. 1. Amylase의 활성은 관부에서 8.36~9.46 unit/mg.rotein/hr.로 가장 높았고 이삭에서 2.04 unit/mg.rotein/hr.로 가장 낮았다. 포복경, 뿌리, 잎에서의 amylase의 활성을 각각 5.42~5.82, 3.76, 2.32~3.16 unit/mg.rotein/hr.나타내었다. 2. Nirate reductase의 활성은 빛을 많이 받는 잎에서 0.35~0.66 n mole/mg.rotein/hr.로 가장 높았고 관부에서 0.06~0.10 n mole/mg.rotein/hr.로 가장 낮았다. 이삭과 포복경에서는 각각 0.31,0.27~0.63 n mole/mg.rotein/hr.를 나타내었다. 이러한 결과로부터 저장기관인 관부나 관부 절간에서 높은 amylase의 활성을 이용하여, 양분을 이삭으로 이동시키고 있음을 알 수 있었다. nitrate reductase의 활성은 chloroplast를 갖지 않는 기관보다 광합성기관에서 더 높았다. 잔디밭에서 같이 사는 크로버와 비교해 보면 amylase의 활성이 Zoysia japonica보다 2배가량 더 높았다. 이러한 결과로부터 잔디밭에서 크로버가 더 생장력이 큼을 알 수 있었다.

• Journal of Plant Biotechnology
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• v.48 no.3
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• pp.124-130
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• 2021

Nitrate is an important nutrient and signaling molecule in plants that modulates the expression of many genes and regulates plant growth. In this study, we cover the research status of transcription factors related to the control of gene expression by nitrate signaling in higher plants. Nitrate reductase is a key enzyme in nitrogen assimilation, as it catalyzes the nitrate-to-nitrite reduction process in plants. A variety of factors, including nitrate, light, metabolites, phytohormones, low temperature, and drought, modulate the expression levels of nitrate reductase genes and nitrate reductase activity, which is consistent with the physiological role if. Recently, several transcription factors controlling the expression of nitrate reductase genes have been identified in higher plants. NODULE-INCEPTION-Like Proteins (NLPs) are transcription factors responsible for the nitrate-inducible expression of nitrate reductase genes. Since NLPs also control the nitrate-inducible expression of genes encoding the nitrate transporter, nitrite transporter, and nitrite reductase, the expression levels of nitrate reduction pathway-associated genes are coordinately modulated by NLPs in response to nitrate. Understanding the function of nitrate in plants will be useful to create crops with low nitrogen use.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.340-345
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• 2001

High rates of nitrogen fertilization dangerously increase the nitrate content of vegetable crops, and the accumulation of nitrate in edible crops is undesirable because of potential risks to human health. Micronutrient solution containing Cu, Mn, Mo, Zn was tested for the suppression of nitrate accumulation in lettuce grown in pots treated with Mg fertilizer under a greenhouse condition. The micronutrient solution was sprayed on leaves at 3 and 4 weeks after transplanting of 20-day old seedlings. Plants were harvested after 5-week growth, and yield, contents of chlorophyll, sugar, micronutrient and nitrate, and also nitrate reductase activity were measured. Fresh weight of lettuce was significantly increased by the application of Mg and micronutrients, and the effect was the most significant in the Mg+micronutrient treatment. Also contents of chlorophyll and micronutrients were higher in the plants of micronutrient treatments. Contents of nitrate were reduced by about 14-18% in lettuce with Mg and/or micronutrient applications. Compared to the plants of control treatment, nitrate reductase activity was also higher in those plants treated with micronutrients, and in the treatment of Mg+micronutrients the enzyme activity was six times as high as that of control treatment. Although the effect of mineral nutrients on the suppression of nitrate accumulation in lettuce was relatively small in this study, an appropriate supply of mineral nutrients could be one of the solutions for the nitrate accumulation in vegetables.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.32-37
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• 2006

In this study, we have purified and characterized the membrane bound nitrate reductase obtained from the denitrifying bacteria, Ochrobactrum anthropi SY509, which was isolated from soil samples. O. anthropi SY509 can grow in minimal medium using nitrate as a nitrogen source. We achieved an overall purification rate of 15-fold from the protein extracted from the membrane fraction, with a recovery of approximately 12% of activity. The enzyme exhibited its highest level of activity at pH 5.5, and the activity was increased up to $70^{\circ}C$. Periplasmic and cytochromic proteins, including nitrite and nitrous oxide reductase, were excluded during centrifugation and were verified using enzyme essay. Reduced methyl viologen was determined to be the most efficient electron donor among a variety of anionic and cationic dyestuffs, which could be also used as an electron donor with dimethyl dithionite. The effects of purification and storage conditions on the stability of enzyme were also investigated. The activity of the membranebound nitrate reductase was stably maintained for over 2 weeks in solution. To maintain the stability of enzyme, the cell was disrupted using sonication at low temperatures, and enzyme was extracted by hot water without any surfactant. The purified enzyme was stored in solution with no salt to prevent any significant losses in activity levels.

• The Korean Journal of Ecology
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• v.15 no.1
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• pp.9-18
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• 1992

Nitrate reductase activity(nra) were analysed in roots, stems and leaves plants in relation to different nitrogen sources and plastochron ages. Nra in roors and stems of soybean observed no differences in influence the nitrogen sources and plastochron ages, and the values showed to be only 5% of NRA in leaves. On the other hand,NRA in the leaves showed different result to nitrgen sources and plastochron ages. When the plants were less than PI6.0, NRA in leaves had being proportional to the concentration of nitrate and distingush decreased with an increasing plastochron age. At the later stage, upper than PI 8.0, the actvity had not effect to nitrate and plastochron ages. These results indicated that nitrate reduction in soybean was in early leaves.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.45-49
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• 2003

Foliar treatment with different concentrations of potassium chloride (KCl) to mulberry plants resulted in higher level of total chlorophyll, total sugars, soluble protein, in vivo nitrate reductase activity (NRA), net photosynthetic rate (NPR), pWUE and leaf yield. Optimal concentration was found to be 10.0 mM KCl with limited irrigation provided in the mulberry plantation planted in 90 ${times}$ 90 cm spacing. The deleterious effect of soil moisture stress condition has been found to be overcome by KCl foliar spray twice at 15 days interval. Regression and correlation coefficients were analyzed, and a strong positive correlation was found between chlorophyll and total sugars, soluble protein and in vivo nitrate reductase activity, leaf dry weight and net photosynthetic rate and pWUE and net photosynthetic rate.