title: Salicylic acid improves salinity tolerance in Arabidopsis by restoring membrane potential and preventing salt-induced K+ loss via a GORK channel.
abstract: 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 short-term 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.
authors.affiliation: School of Earth and Environment, University of Western Australia, Perth, Australia.
authors.forename: Maheswari
authors.initials: M
authors.lastname: Jayakannan
authors.forename: Jayakumar
authors.initials: J
authors.lastname: Bose
authors.forename: Olga
authors.initials: O
authors.lastname: Babourina
authors.forename: Zed
authors.initials: Z
authors.lastname: Rengel
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D011188:Potassium / Q000378:metabolism / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D020156:Salicylic Acid / Q000494:pharmacology*; D055049:Salt Tolerance / Q000187:drug effects* / Q000502:physiology; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology
chemical_list: D010937:Plant Growth Regulators; D015221:Potassium Channels; D012965:Sodium Chloride; D020156:Salicylic Acid; D011188:Potassium
keywords: H+ flux; H+-ATPase; K+ flux; depolarization; membrane potential; outward-rectifying K+ channel; potassium homeostasis.