Sodium efflux in plant roots : what do we really know?

Bibliographische Detailangaben
Veröffentlicht in:	Journal of plant physiology. - 1979. - 186-187(2015) vom: 15. Aug., Seite 1-12
1. Verfasser:	Britto, D T (VerfasserIn)
Weitere Verfasser:	Kronzucker, H J
Format:	Online-Aufsatz
Sprache:	English
Veröffentlicht:	2015
Zugriff auf das übergeordnete Werk:	Journal of plant physiology
Schlagworte:	Journal Article Research Support, Non-U.S. Gov't Review Compartmental analysis Efflux Energetics Ion transport Sodium Toxicity 9NEZ333N27

Beschreibung
Zusammenfassung:	Copyright © 2015 Elsevier GmbH. All rights reserved. The efflux of sodium (Na(+)) ions across the plasma membrane of plant root cells into the external medium is surprisingly poorly understood. Nevertheless, Na(+) efflux is widely regarded as a major mechanism by which plants restrain the rise of Na(+) concentrations in the cytosolic compartments of root cells and, thus, achieve a degree of tolerance to saline environments. In this review, several key ideas and bodies of evidence concerning root Na(+) efflux are summarized with a critical eye. Findings from decades past are brought to bear on current thinking, and pivotal studies are discussed, both "purely physiological", and also with regard to the SOS1 protein, the only major Na(+) efflux transporter that has, to date, been genetically characterized. We find that the current model of rapid transmembrane sodium cycling (RTSC), across the plasma membrane of root cells, is not adequately supported by evidence from the majority of efflux studies. An alternative hypothesis cannot be ruled out, that most Na(+) tracer efflux from the root in the salinity range does not proceed across the plasma membrane, but through the apoplast. Support for this idea comes from studies showing that Na(+) efflux, when measured with tracers, is rarely affected by the presence of inhibitors or the ionic composition in saline rooting media. We conclude that the actual efflux of Na(+) across the plasma membrane of root cells may be much more modest than what is often reported in studies using tracers, and may predominantly occur in the root tips, where SOS1 expression has been localized
Beschreibung:	Date Completed 11.04.2016 Date Revised 08.04.2022 published: Print-Electronic Citation Status MEDLINE
ISSN:	1618-1328
DOI:	10.1016/j.jplph.2015.08.002