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022			_a0176-1617
040			_aMSU _bEnglish _cMSU _erda
050	0	0	_aQK711.2 JOU
100	1		_aBritto, D.T. _eauthor
245	1	0	_aSodium efflux in plant roots: What do we really know? _ccreated by D.T. Britto and H.J. Kronzucker
264	1		_aAmsterdam: _bElsevier GmbH, _c2015.
336			_2rdacontent _atext _btxt
337			_2rdamedia _aunmediated _bn
338			_2rdacarrier _avolume _bnc
440			_aJournal of plant physiology _vVolume 186-187
520	3		_aThe 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.
650			_aSodium
650			_aEfflux
650			_aIon transport
700	1		_aKronzucker, H.J. _eco-author
856			_uhttps://doi.org/10.1016/j.jplph.2015.08.002
942			_2lcc _cJA
999			_c169018 _d169018