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Despite numerous reports implicating salicylic acid (SA) in plant salinity responses, the specific ionic mechanisms of SA-mediated adaptation to salt stress remain elusive. To address this issue, a non-invasive microelectrode ion flux estimation technique was used to study kinetics of NaCl-induced net ion fluxes in Arabidopsis thaliana in response to various SA concentrations and incubation times. NaCl-induced K⁺ efflux and H⁺ influx from the mature root zone were both significantly decreased in roots pretreated with 10–500 μM SA, with strongest effect being observed in the 10–50 μM SA range. Considering temporal dynamics (0–8-h SA pretreatment), the 1-h pretreatment was most effective in enhancing K⁺ retention in the cytosol. The pharmacological, membrane potential, and shoot K⁺ and Na⁺ accumulation data were all consistent with the model in which the SA pretreatment enhanced activity of H⁺-ATPase, decreased NaCl-induced membrane depolarization, and minimized NaCl-induced K⁺ leakage from the cell within the first hour of salt stress. In long-term treatments, SA increased shoot K+ and decreased shoot Na⁺ accumulation. The shortterm NaCl-induced K⁺ efflux was smallest in the gork1-1 mutant, followed by the rbohD mutant, and was highest in the wild type. Most significantly, the SA pretreatment decreased the NaCl-induced K⁺ efflux from rbohD and the wild type to the level of gork1-1, whereas no effect was observed in gork1-1. These data provide the first direct evidence that the SA pretreatment ameliorates salinity stress by counteracting NaCl-induced membrane depolarization and by decreasing K⁺ efflux via GORK channels.

Item Type:	Refereed Article
Keywords:	H+-ATPase, H+ flux, depolarization, K+ flux, membrane potential, outward-rectifying K+ channel, potassium homeostasis
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Environmentally Sustainable Plant Production
Objective Field:	Environmentally Sustainable Plant Production not elsewhere classified
UTAS Author:	Jayakannan, M (Mrs Maheswari Jayakannan)
UTAS Author:	Bose, J (Dr Jayakumar Bose)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	84146
Year Published:	2013
Web of Science® Times Cited:	67
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2013-04-22
Last Modified:	2015-02-04
Downloads:	434 View Download Statistics