Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/44901
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dc.contributor.authorGarnett, T.-
dc.contributor.authorShabala, S.-
dc.contributor.authorSmethurst, P.-
dc.contributor.authorNewman, I.-
dc.date.issued2003-
dc.identifier.citationFunctional Plant Biology: an international journal of plant function, 2003; 30(11):1165-1176-
dc.identifier.issn1445-4408-
dc.identifier.issn1445-4416-
dc.identifier.urihttp://hdl.handle.net/2440/44901-
dc.description.abstractIon-selective microelectrodes were used non-invasively to measure the concentration dependence of NH4+ and NO3– fluxes around the roots of intact solution-cultured Eucalyptus nitens (Deane & Maiden) Maiden. In addition, NH4+ and H+ fluxes were measured simultaneously at a range of NH4+ concentrations, and NO3– and H+ fluxes were measured simultaneously at a range of NO3– concentrations. Nitrogen concentrations ranged from 10–250 μM, i.e. in the range corresponding to the high affinity transport system (HATS). Both NH4+ and NO3– fluxes exhibited saturating Michaelis–Menten-style kinetics. The Km was 16 μM for NH4+ and 18 μM for NO3–. Values of V(max) were 53 nmol m–2 s–1 for NH4+ and 37 nmol m–2 s–1 for NO3–. Proton fluxes were highly correlated with NH4+ and NO3– fluxes, but the relationships were different. Proton efflux increased with increasing NH4+ concentration and mirrored the changing NH4+ fluxes. The ratio between NH4+ and H+ fluxes was 1 : –1.6. Proton influx was evident with initial exposure to NO3–, with the flux stoichiometry for NO3– : H+ being 1 : 1.4. Subsequent increases in NO3– concentration caused a gradual increase in H+ efflux such that the flux stoichiometry for NO3– : H+ became 1 : –0.8. The presence of 100 μM NH4+ greatly reduced NO3– fluxes and caused a large and constant H+ efflux. These results are evidence that E. nitens has a preference for NH4+ as a source of N, and that the fluxes of NH4+ and NO3– are quantitatively linked to H+ flux.-
dc.language.isoen-
dc.publisherC S I R O Publishing-
dc.source.urihttp://dx.doi.org/10.1071/fp03087-
dc.subjectammonium-
dc.subjecteucalyptus-
dc.subjection fluxes-
dc.subjectmicroelectrode-
dc.subjectnitrate-
dc.subjectproton-
dc.titleKinetics of ammonium and nitrate uptake by eucalypt roots and associated proton fluxes measured using ion selective microelectrodes.-
dc.typeJournal article-
dc.contributor.organisationAustralian Centre for Plant Functional Genomics (ACPFG)-
dc.identifier.doi10.1071/FP03087-
pubs.publication-statusPublished-
dc.identifier.orcidGarnett, T. [0000-0003-1664-9659]-
Appears in Collections:Aurora harvest 6
Australian Centre for Plant Functional Genomics publications

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