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Nitrate supply affects ammonium transport in canola roots


Babourina, O and Voltchanskii, K and McGann, B and Newman, IA and Rengel, Z, Nitrate supply affects ammonium transport in canola roots, Journal of Experimental Botany, 58, (3) pp. 651-658. ISSN 0022-0957 (2007) [Refereed Article]

DOI: doi:10.1093/jxb/erl238


Plants may suffer from ammonium (NH4 +) toxicity when NH4 + is the sole nitrogen source. Nitrate (NO 3 -) is known to alleviate NH4 + toxicity, but the mechanisms are unknown. This study has evaluated possible mechanisms of NO3 - alleviation of NH4 + toxicity in canola (Brassica napus L.). Dynamics of net fluxes of NH4 +, H+, K+ and Ca2+ were assessed, using a non-invasive microelectrode (MIFE) technique, in plants having different NO3 - supplies, after single or several subsequent increases in external NH4Cl concentration. After an increase in external NH4Cl without NO3 -, NH4 + net fluxes demonstrated three distinct stages: release (τ1), return to uptake (τ2), and a decrease in uptake rate (τ3). The presence of NO3 - in the bathing medium prevented the τ1 release and also resulted in slower activation of the τ3 stage. Net fluxes of Ca2+ were in the opposite direction to NH4 + net fluxes, regardless of NO3 - supply. In contrast, H + and K+ net fluxes and change in external pH were not correlated with NH4 + net fluxes. It is concluded that (i) NO3 - primarily affects the NH4 + low-affinity influx system; and (ii) NH4 + transport is inversely linked to Ca2+ net flux. © The Author [2007]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Physical Sciences
Research Group:Medical and biological physics
Research Field:Biological physics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Newman, IA (Dr Ian Newman)
ID Code:45563
Year Published:2007
Web of Science® Times Cited:27
Deposited By:Physics
Deposited On:2007-08-01
Last Modified:2009-11-16

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