title: Cytosolic calcium signals elicited by the pathogen-associated molecular pattern flg22 in stomatal guard cells are of an oscillatory nature.
abstract: Changes in cytosolic free calcium ([Ca(2+)]cyt) are an early and essential element of signalling networks activated by the perception of pathogen-associated molecular patterns (PAMPs), such as flg22. The flg22-induced calcium signal has been described on whole-plant, but not on single-cell scale so far. Also, the Ca(2+) sources and channels contributing to its generation are still obscure. Ratiometric fluorescence imaging employing the calcium reporter Yellow Cameleon 3.6 was performed to analyse the flg22-induced calcium signature in single guard cells of Arabidopsis thaliana. Calcium stores and channel types involved in its generation were determined by a pharmacological approach. In contrast to the calcium signal determined on whole-plant level, the signature on single-cell level is not characterized by one sustained response, but by oscillations in [Ca(2+)]cyt. These oscillations were abolished by EGTA and lanthanum, as well as by U73122, neomycin and TMB-8, but only partially or not at all affected by inhibitors of glutamate receptor-like channels and cyclic nucleotide-gated channels. Our analyses suggest that the response observed on whole-plant level is the summary of oscillations occurring in single cells. Parallel to external calcium, influx via channels located at internal stores contributes to the signal.
authors.affiliation: Plant Nutrition Laboratory, Institute of Agricultural and Nutritional Sciences, Faculty of Natural Sciences III, Martin Luther University of Halle-Wittenberg, 06099, Halle (Saale), Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Thor
authors.forename: Edgar
authors.initials: E
authors.lastname: Peiter
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D054884:Host-Pathogen Interactions; D059828:Plant Cells / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D001426:Bacterial Proteins; D002135:Calcium-Binding Proteins; D004791:Enzyme Inhibitors; D004963:Estrenes; D005456:Fluorescent Dyes; D011760:Pyrrolidinones; C495639:yellow cameleon; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D010738:Type C Phospholipases; D002118:Calcium
keywords: Arabidopsis thaliana; Yellow Cameleon; calcium; calcium signal; flagellin; guard cells; pathogen-associated molecular pattern (PAMP); plant-pathogen interactions