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Type: Journal article
Title: First observation of diffusion-limited plant root phosphorus uptake from nutrient solution
Author: Santner, J.
Smolders, E.
Wenzel, W.
Degryse, J.
Citation: Plant Cell and Environment, 2012; 35(9):1558-1566
Publisher: Blackwell Publishing Ltd
Issue Date: 2012
ISSN: 0140-7791
Statement of
Jakob Santner, Erik Smolders, Walter W. Wenzel & Fien Degryse
Abstract: Diffusion towards the root surface has recently been shown to control the uptake of metal ions from solutions. The uptake flux of phosphorus (P) from solutions often approaches the maximal diffusion flux at low external concentrations, suggesting diffusion-controlled uptake also for P. Potential diffusion limitation in P uptake from nutrient solutions was investigated by measuring P uptake of Brassica napus from solutions using P-loaded Al(2) O(3) nanoparticles as mobile P buffer. At constant, low free phosphate concentration, plant P uptake increased up to eightfold and that of passive, diffusion-based samplers up to 40-fold. This study represents the first experimental evidence of diffusion-limited P uptake by plant roots from nutrient solution. The Michaelis constant of the free phosphate ion obtained in unbuffered solutions (K(m) = 10.4 µmol L(-1) ) was 20-fold larger than in the buffered system (K(m) ∼0.5 µmol L(-1) ), indicating that K(m) s determined in unbuffered solutions do not represent the transporter affinity. Increases in the P uptake efficiency of plants by increasing the carrier affinity are therefore unlikely, while increased root surface area or exudation of P-solubilizing compounds are more likely to enhance P uptake. Furthermore, our results highlight the important role natural nanoparticles may have in plant P nutrition.
Keywords: Al2O3 nanoparticles; diffusion limitation; diffusive gradients in thin films; Michaelis constant; Michaelis–Menten kinetics.
Rights: © 2012 Blackwell Publishing Ltd.
RMID: 0020121474
DOI: 10.1111/j.1365-3040.2012.02509.x
Appears in Collections:Agriculture, Food and Wine publications

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