Investigation of the Apparent Induction of Nitrate Uptake in Barley (Hordeum vulgare L.) Using NO3--Selective Microelectrodes (Modulation of Coarse Regulation of NO3- Uptake by Exogenous Application of Downstream Metabolites in the NO3- Assimilatory Pathway)

Henriksen, Gordon H.; Spanswick, Roger M.

doi:10.1104/pp.103.3.885

Cited by 23 publications

(13 citation statements)

References 25 publications

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“…Although there is a constitutive uptake system (Glass, Shaff & Kochian 1992), improved influx is inducible by pretreatment with NO 3 -. Henriksen & Spanswick (1993), with barley roots, found that only NO 3 pretreatment could induce NO 3 uptake from 0·1 mm Ca(NO 3 ) 2 . The influx of the negative NO 3 requires secondary active transport into the negative cytosol under normal conditions.…”

Section: Ammonium and Nitrate Fluxesmentioning

confidence: 98%

“…Other workers (including J. Dunlop and A. Walker, personal comm.) have developed their own systems, without the automation of the two discussed above (Henriksen & Spanswick 1993; Taylor & Bloom 1998; Plassard et al 1999).…”

Section: The Ion‐selective Microelectrode Ion Flux Techniquementioning

confidence: 99%

“…The MIFE™ system, described below, was developed at the University of Tasmania where it has been used to acquire and manage the data in our ion flux studies since 1996 (Newman 2000). The name was first used as an acronym for 'microelectrode ion flux estimation' (Arif & Newman 1993;Henriksen & Spanswick 1993). The method of calculating dV values from the recorded data is illustrated in Fig.…”

Section: The Mife Systemmentioning

confidence: 99%

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Ion transport in roots: measurement of fluxes using ion‐selective microelectrodes to characterize transporter function

Newman

2001

Plant Cell & Environment

269

228

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The transport of mineral ions into and out of tissues and cells is central to the life of plants. Ion transport and the plasma membrane transporters themselves have been studied using a variety of techniques. In the last 15 years, measurement of specific ion fluxes has contributed to the characterization of transport systems. Progress in molecular genetics is allowing gene identification and controlled expression of transporter molecules. However the molecular expression of transporter gene products must be characterized at the functional level. The ionselective microelectrode technique to measure specific ion fluxes non-invasively is ideally suited to this purpose. This technique, its theory, its links with others and its application and prospects in plant science, are discussed. Ions studied include hydrogen, potassium, sodium, ammonium, calcium, chloride and nitrate. Applications discussed include: solute ion uptake by roots; gravitropism and other processes in the root cap, meristematic and elongation zones; Nod factor effect on root hairs; osmotic and salt stresses; oscillations; the effects of light and temperature. Studies have included intact roots, leaf mesophyll and other tissues, protoplasts and bacterial biofilms. A multi-ion capability of the technique will greatly assist functional genomics, particularly when coupled with imaging techniques, patch clamping and the use of suitable mutants.

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Section: Ammonium and Nitrate Fluxesmentioning

confidence: 98%

Section: The Ion‐selective Microelectrode Ion Flux Techniquementioning

confidence: 99%

Section: The Mife Systemmentioning

confidence: 99%

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Ion transport in roots: measurement of fluxes using ion‐selective microelectrodes to characterize transporter function

Newman

2001

Plant Cell & Environment

269

228

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“…It has been found that NH 4 + in the growth solution represses the transcription and activity of the NO 3 -HATS (Aslam et al 1996;Krapp et al 1998), the effect being caused by increased glutamine levels resulting from NH 4 + assimilation (Vidmar et al 2000). However, given the overnight pre-treatment without NH 4 + and the relatively rapid timescale of the NO 3 -HATS induction (Henriksen and Spanswick 1993;Aslam et al 1996) we would assume near full induction of the NO 3 -HATS. The effect of NH 4 + on net NO 3 uptake was immediate and constant across the concentrations measured.…”

Section: Inhibition Of No 3 Flux By Nh 4 +mentioning

confidence: 98%

Kinetics of ammonium and nitrate uptake by eucalypt roots and associated proton fluxes measured using ion selective microelectrodes

Garnett¹,

Shabala²,

Smethurst³

et al. 2003

Functional Plant Biol.

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Ion-selective microelectrodes were used non-invasively to measure the concentration dependence of NH 4 + and NO 3 fluxes around the roots of intact solution-cultured Eucalyptus nitens (Deane & Maiden) Maiden. In addition, NH 4 + and H + fluxes were measured simultaneously at a range of NH 4 + concentrations, and NO 3 and H + fluxes were measured simultaneously at a range of NO 3 concentrations. Nitrogen concentrations ranged from 10-250 µM, i.e. in the range corresponding to the high affinity transport system (HATS). Both NH 4 + and NO 3 fluxes exhibited saturating Michaelis-Menten-style kinetics. The K m was 16 µM for NH 4 + and 18 µM for NO 3 -. Values of V max were 53 nmol m -2 s -1 for NH 4 + and 37 nmol m -2 s -1 for NO 3 -. Proton fluxes were highly correlated with NH 4 + and NO 3 fluxes, but the relationships were different. Proton efflux increased with increasing NH 4 + concentration and mirrored the changing NH 4 + fluxes. The ratio between NH 4 + and H + fluxes was 1:-1.6. Proton influx was evident with initial exposure to NO 3 -, with the flux stoichiometry for NO 3 -:H + being 1:1.4. Subsequent increases in NO 3 concentration caused a gradual increase in H + efflux such that the flux stoichiometry for NO 3 -:H + became 1:-0.8. The presence of 100 µM NH 4 + greatly reduced NO 3 fluxes and caused a large and constant H + efflux. These results are evidence that E. nitens has a preference for NH 4 + as a source of N, and that the fluxes of NH 4 + and NO 3 are quantitatively linked to H + flux.

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“…Assuming that GABA behaves as an organic nitrogen source this observation is actually opposite of what would be predicted, since other amino acids typically reduce rather than accelerate nitrate uptake (Dzuibany et al, 1998;Krapp et al, 1998;Ivashikina and Sokolov, 1997;Padgett and Leonard, 1996;Henriksen and Spanswick, 1993). Assuming that GABA behaves as an organic nitrogen source this observation is actually opposite of what would be predicted, since other amino acids typically reduce rather than accelerate nitrate uptake (Dzuibany et al, 1998;Krapp et al, 1998;Ivashikina and Sokolov, 1997;Padgett and Leonard, 1996;Henriksen and Spanswick, 1993).…”

Section: Increasing the No; Level Reverses The Promotive Effect Of Gamentioning

confidence: 95%

Plant Tolerance to Abiotic Stresses in Agriculture: Role of Genetic Engineering

Cherry¹,

Locy²,

Rychter³

2000

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Investigation of the Apparent Induction of Nitrate Uptake in Barley (Hordeum vulgare L.) Using NO3--Selective Microelectrodes (Modulation of Coarse Regulation of NO3- Uptake by Exogenous Application of Downstream Metabolites in the NO3- Assimilatory Pathway)

Cited by 23 publications

References 25 publications

Ion transport in roots: measurement of fluxes using ion‐selective microelectrodes to characterize transporter function

Ion transport in roots: measurement of fluxes using ion‐selective microelectrodes to characterize transporter function

Kinetics of ammonium and nitrate uptake by eucalypt roots and associated proton fluxes measured using ion selective microelectrodes

Plant Tolerance to Abiotic Stresses in Agriculture: Role of Genetic Engineering

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