Relationship between Nitrate Uptake, Flux, and Reduction and the Accumulation of Reduced Nitrogen in Maize (<i>Zea mays</i> L.)

Reed, Andrew J.; Hageman, R. H.

doi:10.1104/pp.66.6.1179

Cited by 42 publications

(26 citation statements)

References 14 publications

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“…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: 81%

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

et al. 1987

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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.

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

confidence: 81%

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

et al. 1987

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“…The current data show that other factors are involved. The measurements of in vivo NRA (+ N03-) made only during grain development did not reflect the cumulative accumulation of reduced N. When these same genotypes were grown under growth chamber conditions, genotype C had significantly higher NRA and genotype D had accumulated significantly higher amounts of reduced N over 24 days than the other three genotypes, respectively (25). There appeared to be no correlation between leaf NRA and accumulation of reduced N by the shoot; however, in these studies NRA was not monitored daily as awas done with wheat (4).…”

Section: Discussionmentioning

confidence: 92%

Grain Protein Accumulation and the Relationship between Leaf Nitrate Reductase and Protease Activities during Grain Development in Maize (Zea mays L.)

Reed¹,

Below²,

Hageman³

1980

Plant Physiol.

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Four maize hybrids, two with high and two with low levels of postanthesis nitrate reductase activity were grown under field conditions. The characteristic enzyme patterns had been established in previous work. Nitrate reductase and proteases were measured in three representative leaves (ear leaf, fourth leaf above and fourth leaf below the ear) at intervals throughout the period of grain development. Concurrent with enzyme sampling, other plants were harvested and subdivided into top, middle and lower leaves, husks, stalks, and ear. Dry weights, nitrate, and reduced N were determined on aDl plant parts for each samping. These data established the rate of N accumulation by the grain and depletion from the vegetative material and provide some insight into the relation between newly reduced and remobilized N and accumulation of grain N. Other plants were harvested at maturity for yield and harvest indices for dry weight and N.Nitrate reductase activity was higher in comparable leaves from the high than from the low nitrate reductase genotypes throughout the grain development period. There was no mathematical correlation between nitrate reductase activity and nitrate content of the leaves or stalks, however the high nitrate reductase genotypes maintained a higher amount of nitrate per plant (largely in the stalk) during the later stages of grain development.From the patterns of plant nitrate content it was deduced that the low nitrate reductase genotypes terminated nitrate absorption sooner than the high nitrate reductase types. Proteolytic activities (casein as substrate at pH 5.5 and 7.5) were higher and increased earlier in the low than in the high nitrate reductase genotypes. The "low nitrate reductase-high protease" genotypes had a higher percentage of grain N, and higher harvest index for N than did the "high nitrate reductase-low protease" genotypes. These results permit the tentative conclusions that: (a) redistribution of vegetative N accounted for more of the grain N in the low than in the high nitrate reductase genotypes; and (b) leaf protease activities are more closely related to the accumulation of grain N than leaf nitrate reductase activity.Hay et al. (16) (7) showed that a significant correlation between NRA and grain N for five wheat cultivars could be obtained if the N translocation efficiency (ratio of grain N to total plant N) was included in the calculations. Therefore, the efficiency of reduced N redistribution is an important regulatory factor in grain N accumulation. In wheat, acid protease activities were correlated with the loss of reduced N from the upper leaves during grain development (8), and Rao and Croy (24) reported that seedling leaf protease activity was higher in cultivars with high grain N compared to low grain N cultivars. Similarly, leaf protease activity and grain N were found to be related in rice cultivars (22). Feller et al. (I 1) showed that in maize leaves, proteolytic activities (casein as substrate at pH 5.4 and 7.5) increased as leaf protein decreased during ...

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“…Over prolonged periods of NO3-provision, the NO3-content of the root appears to stabilize regardless of external [NO3-1 (2,20). This apparent homeostasis may, in large part, be the result of NO3-efflux.…”

Section: Resultsmentioning

confidence: 99%

Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and ³⁶ClO₃⁻

Deane‐Drummond¹,

Glass²

1983

Plant Physiol.

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A computer-controlled multichannel data acquisition system was employed to obtain continuous measurements of net nitrate or chlorate uptake by roots of intact barley plants (Hordeum vulgare cv Betzes) using nitrate-specific electrodes. Plants, previously grown in solutions maintained at 10 or 200 micromolar N03-(low N or Rates of uptake of the major inorganic nutrients, by roots of higher plants, are extremely sensitive to the availability of these nutrients in the ambient solution. Generally, the capacity for uptake increases with low availability so that internal concentrations tend to be maintained at prescribed levels (2, 13). Such responses have been interpreted to reflect the operation of regulatory mechanisms which may function via negative feedback effects upon the transport systems involved (3,4,11,19,23 (14) demonstrated that NO3-'influx' was reduced and NO3-efflux enhanced by prior growth of wheat seedlings at increasing levels of NO3-(0.25 to 15 mM). However, the term influx in these studies referred to rates of '5NO3 uptake based upon exposures ranging from 0.5 to 6 h. Unfortunately, if the half-life for cytoplasmic exchange is short by comparison to the uptake period, then the measured flux would approximate net uptake rather than unidirectional influx. In these experiments, NO3 efflux increased as the nitrate concentration of the growth medium was increased from 1.0 to 15 mm. Here also, the long term basis ofthe flux measurements (20.5 h) would inevitably lead to an underestimate ofefflux if t1/2for cytoplasmic exchange is short by comparison to flux measurements. Our recently reported estimate of cytoplasmic half-life for NO3 exchange in barley roots (7) suggest that this is indeed the case; t/2 was estimated to be 17 min. Nevertheless, the former study as well as earlier and more recent work from the same laboratory (16-18) attest to the potential importance of efflux in determining net uptake rates.Recently, two techniques which facilitate the measurement of nitrate fluxes over relatively short time periods (610 min) have been reported from this laboratory. First, 36C103-has been demonstrated to be a tracer for nitrate (7). Second, a microcomputer-based system has been described (12) which permits rapid and automatic measurement of ion uptake, using ion-specific electrodes. The frequency with which measurements can be obtained by the latter method leads to extremely sensitive estimates of uptake even in experiments of short duration (5-10 min). The present work was undertaken, using these methods, to explore the relationships between nitrogen status and NO3 flux into barley roots. MATERIALS AND METHODSPlant Culture. Barley plants (Hordeum vulgare L. cv Betzes or Bonanza) were grown hydroponically, in 36-L tanks containing 0.01x Johnson's modified inorganic medium in which NO3 was maintained at 10 gM (low N) or 200 gM (high N) as described in a previous communication (6). Tanks were contained in a Conviron growth cabinet at 26°C and 70% RH and illumination was provided by fluorescent l...

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Relationship between Nitrate Uptake, Flux, and Reduction and the Accumulation of Reduced Nitrogen in Maize (Zea mays L.)

Cited by 42 publications

References 14 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

Grain Protein Accumulation and the Relationship between Leaf Nitrate Reductase and Protease Activities during Grain Development in Maize (Zea mays L.)

Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and ³⁶ClO₃⁻

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Relationship between Nitrate Uptake, Flux, and Reduction and the Accumulation of Reduced Nitrogen in Maize (Zea mays L.)

Cited by 42 publications

References 14 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

Grain Protein Accumulation and the Relationship between Leaf Nitrate Reductase and Protease Activities during Grain Development in Maize (Zea mays L.)

Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and 36ClO3−

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Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and ³⁶ClO₃⁻