Subject(s)
Abscisic Acid/pharmacology , Arabidopsis Proteins , Arabidopsis/metabolism , Cell Division , GTP-Binding Protein alpha Subunits , Heterotrimeric GTP-Binding Proteins/genetics , Heterotrimeric GTP-Binding Proteins/metabolism , Indoleacetic Acids/metabolism , Plant Leaves/cytology , Signal Transduction , Animals , Arabidopsis/cytology , Arabidopsis/genetics , Gene Silencing , Genes, Plant , Guanosine Diphosphate/metabolism , Guanosine Triphosphate/metabolism , Heterotrimeric GTP-Binding Proteins/chemistry , Hydrogen-Ion Concentration , MAP Kinase Signaling System , Models, Biological , Mutation , Plant Cells , Plant Leaves/drug effects , Plant Leaves/physiology , Plant Leaves/ultrastructure , Plants/genetics , Plants/metabolismABSTRACT
Brief exposure to ozone, a potent cross-inducer of plant stress responses, leads within minutes to activation of an ERK-type MAP kinase (approximately 46 kDa) in tobacco. This activation process is calcium-dependent and can be blocked both by free radical quenchers and by a specific inhibitor of MEK-1 (MAPKK). Hydrogen peroxide and superoxide anion radicals can substitute for ozone as the activation stimulus, which does not appear to require salicylate as an intermediary. The properties of the ozone-induced MAPK suggest that it may be SIPK (salicylate-induced protein kinase), a tobacco MAPK that is activated by a variety of stress treatments. The ability of ozone to activate SIPK indicates that this protein kinase acts as a very early transducer of redox stress signals in plant cells.
