Thellungiella halophila, a salt-tolerant relative of Arabidopsis thaliana, has specific root ion-channel features supporting K+/Na+ homeostasis under salinity stress
Article first published online: 27 SEP 2006
The Plant Journal
Volume 48, Issue 3, pages 342–353, November 2006
How to Cite
Volkov, V. and Amtmann, A. (2006), Thellungiella halophila, a salt-tolerant relative of Arabidopsis thaliana, has specific root ion-channel features supporting K+/Na+ homeostasis under salinity stress. The Plant Journal, 48: 342–353. doi: 10.1111/j.1365-313X.2006.02876.x
- Issue published online: 27 SEP 2006
- Article first published online: 27 SEP 2006
- Received 15 May 2006; accepted 21 June 2006.
- Thellungiella halophila;
- Arabidopsis thaliana;
- salt tolerance;
- ion transport;
- ion selectivity;
- voltage-independent channel
Thellungiella halophila is a salt-tolerant relative of Arabidopsis thaliana with high genetic and morphological similarity. In a saline environment, T. halophila accumulates less sodium and retains more potassium than A. thaliana. Detailed electrophysiological comparison of ion currents in roots of both species showed that, unlike A. thaliana, T. halophila exhibits high potassium/sodium selectivity of the instantaneous current. This current differs in its pharmacological profile from the current through inward- and outward-rectifying K+ channels insofar as it is insensitive to Cs+ and TEA+, but resembles voltage-independent channels of glycophytes as it is inhibited by external Ca2+. Addition of Cs+ and TEA+ to the growth medium confirmed the key role of the instantaneous current in whole-plant sodium accumulation. A negative shift in the reversal potential of the instantaneous current under high-salt conditions was essential for decreasing sodium influx to twofold lower than the corresponding value in A. thaliana. The lower overall sodium permeability of the T. halophila root plasma membrane resulted in a smaller membrane depolarization during salt exposure, thus allowing the cells to maintain their driving force for potassium uptake. Our data provide quantitative evidence that specific features of ion channels lead to superior sodium/potassium homeostasis in a halophyte compared with a closely related glycophyte.