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Abstract

Reactive oxygen species (ROS) are known to be primarily
responsible for the impairment of cellular function under
numerous abiotic and biotic stress conditions. In this paper,
using non-invasive microelectrode ion flux measuring
(MIFE) system, we show that the application of a hydroxyl
radical (OH•)-generating Cu2+/ascorbate (Cu/a) mixture to
Arabidopsis roots results in a massive, dose-dependent
efflux of K+ from epidermal cells in the elongation zone.
Pharmacological experiments suggest that both outwardrectifying
K+ channels and non-selective cation channels
(NSCCs) mediate such effluxes. Low (5 mM) concentrations
of compatible solutes (glycine betaine, proline,
mannitol, trehalose or myo-inositol) significantly reduces
OH•-induced K+ efflux, similar to our previous reports for
NaCl-induced K+ efflux. Importantly, a significant reduction
in K+ efflux was found using osmolytes with no reported
free radical scavenging activity, as well as those for which a
role in free radical scavenging has been demonstrated. This
indicates that compatible solutes must play other (regulatory)
roles, in addition to free radical scavenging, in mitigating
the damaging effects of oxidative stress.

Item Type:	Article
Authors/Creators:	Cuin, TA and Shabala, SN
Keywords:	ion flux; potassium channels; reactive oxygen species; root epidermis; stress.
Journal or Publication Title:	Plant Cell and Environment
Publisher:	Blackwell Publishing Ltd
ISSN:	0140-7791
DOI / ID Number:	https://doi.org/10.1111/j.1365-3040.2007.01674.x
Additional Information:	The definitive version is available at www.blackwell-synergy.com
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