title: NaCl-induced changes in cytosolic free Ca2+ in Arabidopsis thaliana are heterogeneous and modified by external ionic composition.
abstract: Increases in cytosolic free Ca(2+) ([Ca(2+)](cyt)) are common to many stress-activated signalling pathways, including the response to saline environments. We have investigated the nature of NaCl-induced [Ca(2+)](cyt) signals in whole Arabidopsis thaliana seedlings using aequorin. We found that NaCl-induced increases in [Ca(2+)](cyt) are heterogeneous and mainly restricted to the root. Both the concentration of NaCl and the composition of the solution bathing the root have profound effects on the magnitude and dynamics of NaCl-induced increases in [Ca(2+)](cyt). Alteration of external K(+) concentration caused changes in the temporal and spatial pattern of [Ca(2+)](cyt) increase, providing evidence for Na(+)-induced Ca(2+) influx across the plasma membrane. The effects of various pharmacological agents on NaCl-induced increases in [Ca(2+)](cyt) indicate that NaCl may induce influx of Ca(2+) through both plasma membrane and intracellular Ca(2+)-permeable channels. Analysis of spatiotemporal [Ca(2+)](cyt) dynamics using photon-counting imaging revealed additional levels of complexity in the [Ca(2+)](cyt) signal that may reflect the oscillatory nature of NaCl-induced changes in single cells.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
authors.forename: Frances E
authors.initials: FE
authors.lastname: Tracy
authors.forename: Matthew
authors.initials: M
authors.lastname: Gilliham
authors.forename: Antony N
authors.initials: AN
authors.lastname: Dodd
authors.forename: Alex A R
authors.initials: AA
authors.lastname: Webb
authors.forename: Mark
authors.initials: M
authors.lastname: Tester
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009355:Neomycin / Q000494:pharmacology; D009994:Osmolar Concentration; D009995:Osmosis / Q000187:drug effects; D017785:Photons; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D012996:Solutions; D013012:Sorbitol / Q000494:pharmacology
chemical_list: D012996:Solutions; D012965:Sodium Chloride; D013012:Sorbitol; D009355:Neomycin; D002118:Calcium