Nitrate Reductase Activity in Maize (<i>Zea mays</i> L.) Leaves

Shaner, Dale L.; Boyer, John S.

doi:10.1104/pp.58.4.499

Cited by 244 publications

(96 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These results agree with those reported by Shaner & Boyer (1976) and Reed & Hageman (1980), which indicate that nitrate flux and NRA are closely related. Other workers (Conejero et al, 1986) have shown that the addition of 4 mM NOg" to nodulated soybeans depressed leaf NRA in comparison with that of nonnodulated plants.…”

Section: Leaves (A) Stems (B) Roots (C) and Nodules (D) Of Foursupporting

confidence: 82%

Effect of Nodulation on the Expression of Nitrate Reductase Activity in Pea Cultivars

et al. 1987

View full text Add to dashboard Cite

SUMMARYNitrate reductase activity (NRA) was measured in leaves, stems, roots and nodules of four cultivars of Pisum sativum L. supplied with 2 mM KNOg and nodulated by selected Rhizobium leguminosarum strains. As a control, non-nodulated (uninoculated) plants were grown in the same nutrient medium. NRA was determined by an in vitro assay; it varied widely among strains and cultivars. Although differences in tissue NRA in nodulated plants were mainly related to cultivar genotype, nodulation much affected the distribution of NRA within the plant. There was also some cultivar x bacteria strain effect. Non-nodulated plants had higher leaf and root NRA than nodulated cultivars, but nodulated plants had twice as high stem NRA as nonnodulated plants. These differences correlated with nitrate concentrations which were depressed in leaves and roots, and increased in stems, of nodulated plants Nitrate accumulation was increased in leaves, stems and roots of nodulated plants in comparison with non-nodulated ones. There were no differences in the root to shoot ratio between nodulated and non-nodulated plants. The relationships between tissue nitrate reduction and nodulation are discussed.

show abstract

Section: Leaves (A) Stems (B) Roots (C) and Nodules (D) Of Foursupporting

confidence: 82%

Effect of Nodulation on the Expression of Nitrate Reductase Activity in Pea Cultivars

et al. 1987

View full text Add to dashboard Cite

show abstract

“…There is some compensation for this impairment by the apparent greater induction of NRA in NaNO3 roots than in KNO roots. The maintenance of high NRA depends on a continuous N03 flux (1,19,20). The high NRA in NaNO3 roots is then the result of N03-absorption at a rate much faster than N03-translocation to leaves.…”

Section: Resultsmentioning

confidence: 99%

“…Blevins et al (4) showed that in roots of barley seedlings treated with Ca(NO3)2, N03-accumulation, organic acid accumulation, and NRA were much less than in KNO3-treated seedlings. Shaner and Boyer (19,20), by using NO3 depletion and cooling of roots and water stress, showed that the decrease in leaf NRA was due to decreased N03 flux to leaves. In wheat seedlings treated with NaNO3, N03-translocation and accumulation were low unless the seedlings had been given a pretreatment with K+ (8).…”

Section: Resultsmentioning

confidence: 99%

Role of Potassium and Malate in Nitrate Uptake and Translocation by Wheat Seedlings

Blevins¹,

Barnett²,

Frost³

1978

Plant Physiol.

View full text Add to dashboard Cite

Wheat seedlings ( Tddcum vulgare) treated with 1 mM KNO3 or NaNO3, in the presence of 0.2 mM CaSO4, were compared during a 48-hour period with respect to nitrate uptake, translocatlon, accumulation and reduction; cation uptake and accumulation; and malate accumulation. Seedlngs treated with KNO3 absord and accumulated more nitrate, had higher nitrate reductase levels in leaves but less in roots, accumulated 17 times more malate in leaves, and accumulated more of the accompanying cation than seedlings treated with NaNO3. Within seedlns of each treatment, changes in nitrate reductase activity and malate accumulation were parallel in leaves and in roots. Despite the great difference in malate accumulation, leaves of the KNO3-treated seedlgs had only slightly greater levels of phosphoenolpyruvate carboxylase than leaves of NaNO3-treated seedlings. NADP-malic enzyme levels increased only slightiy in leaves and roots of both KNO3-and NaNO3-treated seedlns. The effects of K+ and Na+ on all of these parameters can best be explained by their effects on nitrate translocation, which in turn affects the other parameters. In a separate experiment, we confirmed that phospboenolpyruvate carboxylase activity increased about 2-fold during 36 hours of KNO3 treatment, and increased only slightly in the KCI control.(2), in which K+ is an integral part of a NO3--malate shuttle between roots and shoots.Jackson and Coleman (10) first showed the presence of PEP carboxylase in roots, and proposed the PEP carboxylase-malic dehydrogenase pathway for malate accumulation in roots. This pathway, together with malic enzyme for decarboxylation of malate, have been proposed as a mechanism for pH regulation during nitrate assimilation (18, 21), but the hypothesis has not been explicitly tested. We report here the effects of NO3 and its salts on changes in activity of carboxylating and decarboxylating enzymes.Dijkshoorn et al. (6) have shown that internal HCO3, from the decarboxylation of organic acids, was exchanged for external N03 . Also, Ben-Zioni et al. (2) have shown that tobacco roots can secrete more H"CO3-into the medium when N03 is supplied than when Cl-is supplied. The source of H14CO3 was most likely malate, previously synthesized from 14C02 supplied to the leaves.These data also implied an exchange of HCO3 for external NO3.Since there is no a priori reason why this exchange should depend on the presence of K+, we predicted that activity of the reputed decarboxylase, NADP malic enzyme (5), should not be affected by the cation accompanying N03 in the medium. This prediction was fulfilled by experiment.Both the effects of N03-on cation uptake (3, 11) and the effects of different cations on N03-uptake have been studied (4, 15). In some experiments N03 uptake from KNO3 and NaNO3 were nearly the same (16 (Plant Physiol. 56: S-227, 1975 MATERIALS AND METHODSSeeds of wheat (Triticum vulgare L. cv. Arthur) were cultured according to the methods of Blevins et al. (3). The seeds were soaked for 24 hr in continuously aerated deionized ...

show abstract

“…6A). Although in vitro measurements of NR activity may not indicate the actual rate of nitrate assimilation in situ, NR is an inducible enzyme, the activity of which is related to the flux of nitrate through metabolic pools (20). Assuming that the in vitro assays indicate the potential for nitrate reduction in plant tissue (22), the responses of the shoot and root reductase systems to changing nitrate supply (Table I) appear to be consistent with the increased levels of nitrate detected in the xylem stream.…”

Section: Plant Materials and Experimentationmentioning

confidence: 99%

Nitrogen Nutrition and Xylem Sap Composition of Peanut (Arachis hypogaea L. cv Virginia Bunch)

Peoples¹,

Pate²,

Atkins³

et al. 1986

Plant Physiol.

View full text Add to dashboard Cite

The principal forms of amino nitrogen transported in xylem were studied in nodulated and non-nodulated peanut (Arachis hypogaea L.). In symbiotic plants, asparagine and the nonprotein amino acid, 4-methyleneglutamine, were identified as the major components of xylem exudate collected from root systems decapitated below the lowest nodule or above the nodulated zone. Sap bleeding from detached nodules carried 80% of its nitrogen as asparagine and less than 1% as 4-methyleneglutamine.Pulse-feeding nodulated roots with`5N2 gas showed asparagine to be the principal nitorgen product exported from N2-fixing nodules. Maintaining root systems in an N2-deficient (argon:oxygen, 80:20, v/v) atmosphere for 3 days greatly depleted asparagine levels in nodules. 4-Methyleneglutamine represented 73% of the total amino nitrogen in the xylem sap of non-nodulated plants grown on nitrogen-free nutrients, but relative levels of this compound decreased and asparagine increased when nitrate was supplied. The presence of 4-methyleneglutamine in xylem exudate did not appear to be associated with either N2 fixation or nitrate assimilation, and an origin from cotyledon nitrogen was suggested from study of changes in amount of the compound in tissue amino acid pools and in root bleeding xylem sap following germination. Changes in xylem sap composition were studied in nodulated plants receiving a range of levels of 'IN-nitrate, and a 'IN dilution technique was used to determine the proportions of accumulated plant nitrogen derived from N2 or fed nitrate. The abundance of asparagine in xylem sap and the ratio of asparagine:nitrate fell, while the ratio of nitrate:total amino acid rose as plants derived less of their organic nitrogen from N2. Assays based on xylem sap composition are suggested as a means of determining the relative extents to which N2 and nitrate are being used in peanuts.Despite the importance of peanut (Arachis hypogaea L.) as an oil or protein seed crop, relatively little research has been directed at the assimilation and metabolism of nitrogen in the species.The classic study ofFowden (7) identified the unusual substituted amide, 4-methyleneglutamine, as the major form of nitrogen transported in xylem from roots to shoot and leaves of peanut seedlings, and a more recent study (23) confirmed this finding in showing that both 4-Megln2 and the free acid 4-methyleneglutamic acid were synthesized rapidly from cotyledon nitrogen following germination. Winter et al. (23)

show abstract

Nitrate Reductase Activity in Maize (Zea mays L.) Leaves

Cited by 244 publications

References 17 publications

Effect of Nodulation on the Expression of Nitrate Reductase Activity in Pea Cultivars

Effect of Nodulation on the Expression of Nitrate Reductase Activity in Pea Cultivars

Role of Potassium and Malate in Nitrate Uptake and Translocation by Wheat Seedlings

Nitrogen Nutrition and Xylem Sap Composition of Peanut (Arachis hypogaea L. cv Virginia Bunch)

Contact Info

Product

Resources

About