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Sequential depolarization of root cortical and stelar cells induced by an acute salt shock - implications for Na+ and K+ transport into xylem vessels

journal contribution
posted on 2023-05-17, 07:31 authored by Wegner, LH, Stefano, G, Svetlana ShabalaSvetlana Shabala, Rossi, M, Mancuso, S, Sergey ShabalaSergey Shabala
Early events in NaCl-induced root ion and water transport were investigated in maize (Zeamays L) roots using a range of microelectrode and imaging techniques. Addition of 100 mM NaCl to the bath resulted in an exponential drop in root xylem pressure, rapid depolarization of trans-root potential and a transient drop in xylem K+ activity (AK+) within ~1 min after stress onset. At this time, no detectable amounts of Na+ were released into the xylem vessels. The observed drop in AK+ was unexpected, given the fact that application of the physiologically relevant concentrations of Na+ to isolated stele has caused rapid plasma membrane depolarization and a subsequent K+ efflux from the stelar tissues. This controversy was explained by the difference in kinetics of NaCl-induced depolarization between cortical and stelar cells. As root cortical cells are first to be depolarized and lose K+ to the environment, this is associated with some K+ shift from the stelar symplast to the cortex, resulting in K+ being transiently removed from the xylem. Once Na+ is loaded into the xylem (between 1 and 5 min of root exposure to NaCl), stelar cells become more depolarized, and a gradual recovery in AK+ occurs.


Publication title

Plant, Cell and Environment










Tasmanian Institute of Agriculture (TIA)


Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

© 2011 Blackwell Publishing Ltd The definitive published version is available online at:

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Socio-economic Objectives

Grains and seeds not elsewhere classified

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