The Role of Light and Nitrate in the Induction of Nitrate Reductase in Radish Cotyledons and Maize Seedlings

Beevers, Leonard; Schrader, L. E.; Flesher, Donna; Hageman, R. H.

doi:10.1104/pp.40.4.691

Cited by 217 publications

(114 citation statements)

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“…A similar light-dependence of nitrate reductase has been found in several higher plants [4][5][6][7]9, 1 I], pro ducing daily fluctuations of the enzyme activity [8].…”

Section: Resultssupporting

confidence: 60%

The influence of light on the activity of nitrate reductase in synchronous cultures of Chlorella pyrenoidosa

et al. 1972

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“…A similar light-dependence of nitrate reductase has been found in several higher plants [4][5][6][7]9, 1 I], pro ducing daily fluctuations of the enzyme activity [8].…”

Section: Resultssupporting

confidence: 60%

The influence of light on the activity of nitrate reductase in synchronous cultures of Chlorella pyrenoidosa

et al. 1972

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“…To study further the effect of AMP, ADP, and ATP upon in vitro nitrate reduction, crude homogenates were made of leaves from corn and giant foxtail plants pretreated with either 8 hr of darkness or 4 hr of illumination. In both species, whether taken from the dark or exposed to 4 Nelson and Ilan (30) reported that ADP (concentrations of 2 mm and above) inhibited (12-60%) preparations of nitrate reductase. This ADP inhibition has been confirmed in this laboratory with wheat leaf extracts, but with inhibitions approaching only 10% (with 2 mm ADP).…”

Section: Resultsmentioning

confidence: 99%

“…7B), illumination of the pigweed plants resulted in a doubling of the NAD-dependent GPD activity within 4 hr with the bulk of the increase occurring in the first 2 hr. The initial level of GPD was only one-tenth that obtained with the corn tissue (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Leaf tips 4 to 5 cm long were cut from the first true leaf of 10-day-old corn plants and 20-day-old foxtail plants. The 4 Subsequent work done after completion of the thesis has shown that higher amounts (1.5-to 2.0-fold) of nitrite are produced if the concentration of potassium phosphate is 0.10 M instead of 0.001 M. leaves were quickly weighed, then washed twice in distilled deionized water to remove any exogenous nitrate, and excess water was removed by blotting. The basal ends of the leaves were placed into 5 ml of aqueous medium contained in a 25-ml beaker.…”

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Generation of Reduced Nicotinamide Adenine Dinucleotide for Nitrate Reduction in Green Leaves

1971

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An in vivo assay of nitrate reductase activity was developed by vacuum infiltration of leaf discs or sections with a solution of 0.2 M KNO3 (with or without phosphate buffer, pH 7.5) and incubation of the infiltrated tissue and medium under essentially anaerobic conditions in the dark. Nitrite production, for computing enzyme activity, was determined on aliquots of the incubation media, removed at intervals.By adding, separately, various metabolites of the glycolytic, pentose phosphate, and citric acid pathways to the infiltrating media, it was possible to use the in vivo assay to determine the prime source of reduced nicotinamide adenine dinucleotide (NADH) required by the cytoplasmically located NADH-specific nitrate reductase. It was concluded that sugars that migrate from the chloroplast to the cytoplasm were the prime source of energy and that the oxidation of glyceraldehyde 3-phosphate was ultimately the in vivo source of NADH for nitrate reduction.This conclusion was supported by experiments that included: inhibition studies with iodoacetate; in vitro studies that established the presence and functionality of the requisite enzymes; and studies showing the effect of light (photosynthate) and exogenous carbohydrate on loss of endogenous nitrate from plant tissue.The level of nitrate reductase activity obtained with the in vitro assay is higher (2.5-to 20-fold) than with the in vivo assay for most plant species. The work done to date would indicate that the in vivo assays are proportional to the in vitro assays with respect to ranking genotypes for nitrate-reducing potential of a given species. The in vivo assay is especially useful in studying nitrate assimilation in species like giant ragweed from which onlv traces of active nitrate reductase can be extracted.indirectly via oxidation of carbohydrates produced photosynthetically. Work with illuminated algae and Perilla (42,9,20) suggests that carbohydrate oxidation is directly involved in nitrate reduction and thus would be similar to the process operative in nonchlorophyllous tissue (45). In contrast, Mendel and Visser (28) deduced from studies with 15N-nitrate using tomato leaves that nitrate reduction and assimilation was dependent on respiratory (mitochondrial) energy in the dark while a separate light-dependent pathway was operative with illumination. The isolation of a NAD(P)H-nitrate reductase from soybean leaves and the demonstration that a reconstituted system of enzyme, grana, and NADP when illuminated would reduce nitrate seemed to establish the coupling of light via an electron transport system to nitrate reduction (11). Doubt was cast upon this conclusion by the subsequent findings that nitrate reductase in leaf tissue (including soybeans) is NADHdependent (2, 3, 44), nitrate reductase is localized in the cytoplasm and not within the chloroplasts (34, 36), and pyridine nucleotides do not readily migrate from the chloroplasts (18,31). In contrast, several photosynthetic metabolites (3-PGA, 3-PGAId, 3-DHAP, and RDP are most mobile)3 mig...

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“…Nitrate alone, however, is not always sufficient to induce the enzyme in higher plants. Light [2] and C 0 2 [3] are also necessary, suggesting that photosynthesis furnishes some essential component of the induction process triggered by nitrate. We have previously shown [4] that induction of nitrate reductase may be obtained by spraying suitable amounts of plant hormones on the leaves of tobacco plants in the dark.…”

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Nitrate Reductase as a Product‐Inducible Enzyme

Kaplan

Roth‐Bejerano

Lips

1974

European Journal of Biochemistry

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Nitrite is a very effective inducer of nitrate reductase. Nitrate induces the enzyme in darkness only upon addition of suitable sources of reducing equivalent which permit the formation of nitrite; nitrite itself brings about induction of the enzyme in darkness without supplementation of exogenous reducing cofactors. Inhibition of constitutive nitrate reductase by tungstate prevents induction of the enzyme by nitrate but not by nitrite. Since nitrate induces the enzyme only under conditions allowing production of nitrite while the induction capacity of nitrite is free of this constraint, nitrate reductase be considered a product-inducible rather than a substrate-inducible enzyme.The ability of nitrate to induce nitrate reductase in higher plants has been widely accepted [l]. Nitrate alone, however, is not always sufficient to induce the enzyme in higher plants. Light [2] and C 0 2 [3] are also necessary, suggesting that photosynthesis furnishes some essential component of the induction process triggered by nitrate. We have previously shown [4] that induction of nitrate reductase may be obtained by spraying suitable amounts of plant hormones on the leaves of tobacco plants in the dark. It has been shown also that adding certain respiratory substrates to nitrate in etiolated barley leaves allows induction of the enzyme in the dark [5]. Nitrate, therefore, promotes induction of nitrate reductase only under conditions which permit formation of nitrite. The reduction of nitrate requires photosynthesis of a carbon compound which yields, upon oxidation, the electrons necessary for the reduction. We have suggested [6] that glycolate is the photosynthetic compound required for nitrate reduction because the enzyme system which oxidizes glycolate and the enzyme-reducing nitrate are located in microbodies. Glycolate dehydrogenase activity has been detected in plants actively reducing nitrate [7].Nitrate reduction takes place in the dark when the leaves are supplemented with suitable respiratory substrates [5] such as glucose, phosphoglyceric acid or glycolate ; this exogeneous supply substitutes photosynthesis as a source of energy-yielding substrates for the reduction of nitrate and the generation of nitrite.Since reduction of nitrate to nitrite takes place in both cases (photosynthesis or supplementation of Enzyme. Nitrate Reductase [NAD(P)H] (EC 3.6.6.2).-~ suitable respiratory substrates), the possible involvement of nitrite as the inducer of nitrate reductase should be considered. MATERIALS AND METHODS Plant MaterialEtiolated barley (Hordeum vulgare L., var. Esperanza) leaves were obtained from seedlings germinated and grown in the dark for 7-9 days. The plants were grown in 0.5 mM CaS0, at 24°C. Other barley seeds were germinated and grown in the light for the same period of time (7-9 days) in 0.5 mM CaSO,. These plants constituted the source of "green leaves" used in some of the experiments described. Induction ProcedureInduction of nitrate reductase was obtained by placing detached leaves in petri dishes (10 cm dia...

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The Role of Light and Nitrate in the Induction of Nitrate Reductase in Radish Cotyledons and Maize Seedlings

Cited by 217 publications

References 5 publications

The influence of light on the activity of nitrate reductase in synchronous cultures of Chlorella pyrenoidosa

The influence of light on the activity of nitrate reductase in synchronous cultures of Chlorella pyrenoidosa

Generation of Reduced Nicotinamide Adenine Dinucleotide for Nitrate Reduction in Green Leaves

Nitrate Reductase as a Product‐Inducible Enzyme

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