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Silver ions disrupt K+ homeostasis and cellular integrity in intact barley (Hordeum vulgare L.) roots
- Source :
- Journal of Experimental Botany
- Publication Year :
- 2011
- Publisher :
- Oxford University Press (OUP), 2011.
-
Abstract
- The heavy metals silver, gold, and mercury can strongly inhibit aquaporin-mediated water flow across plant cell membranes, but critical examinations of their side effects are rare. Here, the short-lived radiotracer (42)K is used to demonstrate that these metals, especially silver, profoundly change potassium homeostasis in roots of intact barley (Hordeum vulgare L.) plants, by altering unidirectional K(+) fluxes. Doses as low as 5 μM AgNO(3) rapidly reduced K(+) influx to 5% that of controls, and brought about pronounced and immediate increases in K(+) efflux, while higher doses of Au(3+) and Hg(2+) were required to produce similar responses. Reduced influx and enhanced efflux of K(+) resulted in a net loss of40% of root tissue K(+) during a 15 min application of 500 μM AgNO(3), comprising the entire cytosolic potassium pool and about a third of the vacuolar pool. Silver also brought about major losses of UV-absorbing compounds, total electrolytes, and NH(4)(+). Co-application, with silver, of the channel blockers Cs(+), TEA(+), or Ca(2+), did not affect the enhanced efflux, ruling out the involvement of outwardly rectifying ion channels. Taken together with an examination of propidium iodide staining under confocal microscopy, the results indicate that silver ions affect K(+) homeostasis by directly inhibiting K(+) influx at lower concentrations, and indirectly inhibiting K(+) influx and enhancing K(+) efflux, via membrane destruction, at higher concentrations. Ni(2+), Cd(2+), and Pb(2+), three heavy metals not generally known to affect aquaporins, did not enhance K(+) efflux or cause propidium iodide incorporation. The study reveals strong and previously unknown effects of major aquaporin inhibitors and recommends caution in their application.
- Subjects :
- 0106 biological sciences
Silver
Physiology
Water flow
Potassium
Aquaporin
chemistry.chemical_element
Plant Science
Biology
Aquaporins
Plant Roots
barley (Hordeum vulgare L.)
01 natural sciences
ion transport
03 medical and health sciences
chemistry.chemical_compound
Homeostasis
Channel blocker
Propidium iodide
heavy metals
Ion transporter
030304 developmental biology
0303 health sciences
Hordeum
Research Papers
chemistry
Biochemistry
membrane integrity
Biophysics
Efflux
Hordeum vulgare
010606 plant biology & botany
Subjects
Details
- ISSN :
- 14602431 and 00220957
- Volume :
- 63
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Botany
- Accession number :
- edsair.doi.dedup.....b18589d92d64aa260c5a7b38ff80db0a