title: Biochemical evidence for the activation of distinct subsets of mitogen-activated protein kinases by voltage and defense-related stimuli.
abstract: Activation of mitogen-activated protein (MAP) kinases is a common reaction of plant cells in defense-related signal transduction pathways. To gain insight into the mechanisms that determine specificity in response to a particular stimulus, a biochemical approach has been employed. Photoautotrophic suspension culture cells of tomato (Lycopersicon peruvianum) were used as experimental system to characterize MAP kinase activation by different stress-related stimuli. An elicitor preparation of the tomato-specific pathogen Fusarium oxysporum lycopersici was shown to result in the simultaneous induction of four kinase activities that could be separated by ion-exchange chromatography. The simultaneous activation of multiple MAP kinases was further substantiated by distinct pharmacological and immunological properties: a differential sensitivity toward various protein kinase inhibitors and a differential cross-reaction with isoform-specific MAP kinase antibodies. In contrast to the two fungal elicitors chitosan and the F. oxysporum lycopersici preparation, the plant-derived stimuli polygalacturonic acid and salicylic acid were shown to activate distinctly different subsets of MAP kinases. Application of a voltage pulse was introduced as a transient stress-related stimulus that does not persist in the culture. Voltage application activates a distinct set of MAP kinases, resembling those activated by salicylic acid treatment, and generates a refractory state for the salicylic acid response. The inhibitory effect of nifedipine indicates that current application may directly affect voltage-gated calcium channels, thus, providing a tool to study various calcium-dependent pathways.
authors.affiliation: Institut für Pharmazeutische Biologie, Universität Würzburg, Julius-von-Sachs-Platz 2-4, 97082 Würzburg, Germany.
authors.forename: Vinzenz L
authors.initials: VL
authors.lastname: Link
authors.forename: Markus G
authors.initials: MG
authors.lastname: Hofmann
authors.forename: Alok K
authors.initials: AK
authors.lastname: Sinha
authors.forename: Rainer
authors.initials: R
authors.lastname: Ehness
authors.forename: Miroslav
authors.initials: M
authors.lastname: Strnad
authors.forename: Thomas
authors.initials: T
authors.lastname: Roitsch
mesh_terms: D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D002686:Chitin / Q000031:analogs & derivatives / Q000494:pharmacology; D048271:Chitosan; D004558:Electric Stimulation; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D005670:Fusarium / Q000254:growth & development*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007113:Immunity, Innate; D018551:Solanum lycopersicum / Q000166:cytology / Q000201:enzymology* / Q000382:microbiology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D010368:Pectins / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology
chemical_list: D000906:Antibodies; D002121:Calcium Channel Blockers; D012333:RNA, Messenger; D002686:Chitin; D010368:Pectins; D048271:Chitosan; D006861:Hydrogen Peroxide; D020928:Mitogen-Activated Protein Kinases; D009543:Nifedipine; D020156:Salicylic Acid; D002118:Calcium; C003181:polygalacturonic acid