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Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium
Author(s) -
Wegner L. H.,
Sattelmacher B.,
Läuchli A.,
Zimmermann U.
Publication year - 1999
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1999.00506.x
Subject(s) - xylem , depolarization , apoplast , hyperpolarization (physics) , membrane potential , symplast , ammonium , chemistry , nitrate , biophysics , microelectrode , botany , biology , biochemistry , cell wall , electrode , organic chemistry , nuclear magnetic resonance spectroscopy
Upon addition of nitrate and ammonium, respectively, to the bath of intact ‘low salt’ maize plants, the cortical membrane potential and the trans‐root potential changed in a similar and synchronous way as revealed by applying conventional microelectrode techniques and the xylem pressure‐potential probe ( Wegner & Zimmermann 1998). Upon addition of nitrate, a hyperpolarization response was observed which was frequently preceded by a short depolarization phase. In contrast, addition of ammonium resulted in an overall depolarization response both of the cortical membrane potential and the trans‐root potential. The nitrate‐induced hyperpolarization response and the depolarization following the addition of ammonium were concentration‐dependent. The data suggest that a tight electrical coupling exists between the cellular and tissue level in the root of the intact plant and that the resistance of the cellular (symplastic) space is much less than the resistance of the apoplast.