Intercellular Localization of Nitrate Reductase in Roots

Rufty, Thomas W.; Thomas, Judith F.; Remmler, Jill; Campbell, Wilber H.; Volk, Richard J.

doi:10.1104/pp.82.3.675

Cited by 79 publications

(49 citation statements)

References 21 publications

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“…First, reduction of NO 3 Ϫ to NO 2 Ϫ occurs in the cytosol (29,30) and requires NADH generated from malate that is shuttled from the chloroplast (31). The demands of carbon fixation for reductant might limit this malate shuttle.…”

Section: Resultsmentioning

confidence: 99%

Nitrogen assimilation and growth of wheat under elevated carbon dioxide

Bloom

Smart

Nguyen

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

193

173

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A tmospheric CO 2 concentrations have increased from about 280 to 370 mol mol Ϫ1 since 1800 (1, 2) and may reach 500-900 mol mol Ϫ1 by the end of the century (3). Several responses of higher plants to such changes were not anticipated (4). For example, a doubling of CO 2 level initially accelerates carbon fixation in C 3 plants by about 30%, yet after days to weeks of exposure to high CO 2 concentrations, depending on species, carbon fixation declines until it stabilizes at a rate that averages 12% above ambient controls (5). This general phenomenon, known as CO 2 acclimation, is correlated with a decline in the activity of Rubisco and other enzymes in the Calvin cycle (6, 7). The change in Calvin cycle enzyme activities is not necessarily selective; rather, it often follows a decline in overall shoot protein and N contents (8). Shoot N contents diminish by an average of 14% with a doubling of CO 2 (9), a difference that exceeds what would be expected if a given amount of N were diluted by additional biomass (8).In wheat, CO 2 acclimation varies with N supply (10, 11). Wheat shoots accumulate free NO 3 Ϫ under elevated CO 2 (12), and shoot protein declines (13) despite little change in total N (12, 14). Here, we present several lines of evidence that elevated CO 2 concentrations inhibit NO 3 Ϫ assimilation in wheat shoots and suggest two physiological mechanisms for this phenomenon. Materials and MethodsWe surface-sterilized wheat (Triticum aestivum cv. Veery 10) seeds for 1 min in 2.6% NaClO, washed them thoroughly with water, and germinated them for several days on thick paper toweling (germination paper) saturated with 1 mM CaSO 4 . Twenty seedlings were transplanted to 19-liter opaque plastic containers filled with an aerated nutrient solution containing 0.2 mM NH 4 NO 3 , 1 mM CaSO 4 , 0.5 mM K 2 HPO 4 , 0.5 mM KH 2 PO 4 , 1 mM MgSO 4 , 0.2 g liter Ϫ1 Fe-NaEDTA, and micronutrients (15). The nutrient solution was replenished every 3 days.The containers were placed in a controlled environment chamber [Conviron (Winnipeg, MB, Canada) PGV-36] equipped with a nondispersive infrared CO 2 analyzer (Horiba, Kyoto, no. APBA-250E) and a Conviron process controller that added CO 2 to maintain the chamber concentration at 360 mol mol Ϫ1 for the photon flux density (PFD) response experiments (i.e., shoot photosynthesis as a function of photosynthetic PFD at plant height) and either 360 or 700 mol mol Ϫ1 for the A-C i response (i.e., shoot photosynthesis as a function of internal CO 2 concentration) experiments. The growth͞N relations experiments were also conducted at 360 or 700 mol CO 2 mol Ϫ1 . The CO 2 added was filtered through a KMnO 4 column to remove contaminating hydrocarbons such as ethylene. A combination of high-pressure sodium, metal halide, and incandescent lamps provided a photosynthetic PFD of 700 mol m Ϫ2 s Ϫ1 at plant height. The light͞dark period was 16 h͞8 h at 25°C and 15°C, respectively.Gas-Exchange Measurements. We transferred a seedling about 14 days old into a measurement system in which a split ...

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Section: Resultsmentioning

confidence: 99%

Nitrogen assimilation and growth of wheat under elevated carbon dioxide

Bloom

Smart

Nguyen

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

193

173

View full text Add to dashboard Cite

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“…We have recently suggested (17) that in cells actively engaged in the reduction of nitrate, particularly epidermal cells, [NO3 ] values may be much lower than in inner cortical cells, which have been reported to contain but a small proportion ofroot nitrate reductase activity (13). However, even if [NO3Y] values were sufficiently low to accommodate a channel-mediated flux in thermodynamic terms, the depolarizing effect of high NO3-still remains to be accounted for.…”

Section: Growth Of Plantsmentioning

confidence: 99%

Studies of the Uptake of Nitrate in Barley

Glass¹,

Shaff²,

Kochian³

1992

Plant Physiol.

249

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Transmembrane electrical potential differences (AS) of epidermal and cortical cells were measured in intact roots of barley (Hordeum vulgare L. cv Klondike). The effects of exogenous N03-on AA (in the concentration range from 100 micromolar to 20 millimolar) were investigated to probe the mechanisms of nitrate uptake by the high-affinity (HATS) and low-affinity (LATS) transport systems for N03-uptake. number of species by means of electrophysiological studies. Ullrich and Novacky (19) documented that NO3-absorption by Lemna was associated with depolarization of the A,. Furthermore, the extent ofdepolarization of A# was increased ("induced") by prior exposure of NO3-deprived plants to N03-solutions in the same way that NO3-uptake is enhanced ("induced") by exposure to NO3-. Depolarization of A, was followed by gradual repolarization of the electrical potential difference (in the presence of exogenous NO3-), presumably through activation of the proton pump. Removal of NO3-caused hyperpolarization of A{. A mechanism for NO3-absorption involving a 2 H+: 1 NO3-symport was proposed to account for these observations, whereby the energy for active NO3-absorption is derived from the proton gradient (AWH+) generated by the plasma membrane H+-ATPase.By contrast, Thibaud and Grignon (18) reported that N03 absorption by corn roots was associated with hyperpolarization of A+. Furthermore, the failure of diethylstilbestrol (an inhibitor of H+-translocating ATPases) to inhibit this hyperpolarization led these authors to propose that NO3-absorption in corn roots occurred by means of a 2 N03-:1 OHantiport. More

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“…NR is found largely in the cytosols of root epidermal and cortical cells as well as in shoot mesophyll cells (Rufty et al, 1986;Vaughn and Campbell, 1988;Fedorova et al, 1994). Incidentally, these are also sites of heavy metal bioconcentration.…”

Section: Resultsmentioning

confidence: 99%

Plant growth response and nitrate reductase activities of roots of Chromolaena odorata in a model spent lubricating oil-polluted soil

Anoliefo¹,

Ikhajiagbe²,

Omoregie³

et al. 2017

Studia UBB Biologia

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SUMMARY.The ability of Chromolaena odorata propagated by stem cuttings and grown for 50 days in the soil containing five (5) different concentrations of spent lubricating oil (SLO) in soil (0, 1, 3, 6, 9 and 12 % SLO), was investigated. The experiments were watered daily at 70% moisture field capacity. Parameters such as number leaves per plant, shoot length, plant height as well as nitrate reductase activities were measured. Shoot length as well as leaf number were significantly (p < 0.05) reduced, compared to the control treatment. Results also showed that nitrate reductase activities increased slightly with time. However, beyond 40 days, nitrate reductase activity was not detected in 3% -12% w/w oil-in-soil treatments, respectively. Pollution indices such as Contamination factor and Hazard Quotient, used in the present study indicated significant reduction in contamination values upon sowing of C. Odorata. Values obtained from Bioaccumulation Quotients also indicated that the plant was able to significantly bioaccumulate elements such as Fe, Cu and Ni present in the SLO-polluted soil.

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Intercellular Localization of Nitrate Reductase in Roots

Cited by 79 publications

References 21 publications

Nitrogen assimilation and growth of wheat under elevated carbon dioxide

Nitrogen assimilation and growth of wheat under elevated carbon dioxide

Studies of the Uptake of Nitrate in Barley

Plant growth response and nitrate reductase activities of roots of Chromolaena odorata in a model spent lubricating oil-polluted soil

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