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Extracellular Ca2+ ameliorates NaCl-induced K+ loss from Arabidopsis root and leaf cells by controlling plasma membrane K+-permeable channels


Shabala, SN and Demidchik, V and Shabala, L and Cuin, TA and Smith, SJ and Miller, AJ and Davies, JM and Newman, IA, Extracellular Ca2+ ameliorates NaCl-induced K+ loss from Arabidopsis root and leaf cells by controlling plasma membrane K+-permeable channels, Plant Physiology, 141, (4) pp. 1653-1665. ISSN 0032-0889 (2006) [Refereed Article]

DOI: doi:10.1104/pp.106.082388


Calcium can ameliorate Na + toxicity in plants by decreasing Na + influx through nonselective cation channels. Here, we show that elevated external [Ca 2+] also inhibits Na +-induced K + efflux through outwardly directed, K +-permeable channels. Noninvasive ion flux measuring and patch-clamp techniques were used to characterize K + fluxes from Arabidopsis (Arabidopsis thaliana) root mature epidermis and leaf mesophyll under various Ca 2+ to Na + ratios. NaCl-induced K + efflux was not related to the osmotic component of the salt stress, was inhibited by the K + channel blocker TEA +, was not mediated by inwardly directed K + channels (tested in the akt1 mutant), and resulted in a significant decrease in cytosolic K + content. NaCl-induced K + efflux was partially inhibited by 1 mM Ca 2+ and fully prevented by 10 mM Ca 2+. This ameliorative effect was at least partially attributed to a less dramatic NaCl-induced membrane depolarization under high Ca 2+ conditions. Patch-clamp experiments (whole-cell mode) have demonstrated that two populations of Ca 2+-sensitive K + efflux channels exist in protoplasts isolated from the mature epidermis of Arabidopsis root and leaf mesophyll cells. The instantaneously activating K + efflux channels showed weak voltage dependence and insensitivity to external and internal Na +. Another population of K + efflux channels was slowly activating, steeply rectifying, and highly sensitive to Na +. K + efflux channels in roots and leaves showed different Ca 2+ and Na + sensitivities, suggesting that these organs may employ different strategies to withstand salinity. Our results suggest an additional mechanism of Ca 2+ action on salt toxicity in plants: the amelioration of K + loss from the cell by regulating (both directly and indirectly) K + efflux channels. © 2006 American Society of Plant Biologists.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Crop and pasture biochemistry and physiology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Grains and seeds
Objective Field:Barley
UTAS Author:Shabala, SN (Professor Sergey Shabala)
UTAS Author:Shabala, L (Associate Professor Lana Shabala)
UTAS Author:Cuin, TA (Dr Tracey Cuin)
UTAS Author:Newman, IA (Dr Ian Newman)
ID Code:39795
Year Published:2006
Web of Science® Times Cited:334
Deposited By:Agricultural Science
Deposited On:2006-08-01
Last Modified:2014-02-03

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