title: The role of the kinase OXI1 in cadmium- and copper-induced molecular responses in Arabidopsis thaliana.
abstract: The hypothesis that mitogen-activated protein kinase (MAPK) signalling is important in plant defences against metal stress has become accepted in recent years. To test the role of oxidative signal-inducible kinase (OXI1) in metal-induced oxidative signalling, the responses of oxi1 knockout lines to environmentally realistic cadmium (Cd) and copper (Cu) concentrations were compared with those of wild-type plants. A relationship between OXI1 and the activation of lipoxygenases and other initiators of oxylipin production was observed under these stress conditions, suggesting that lipoxygenase-1 may be a downstream component of OXI1 signalling. Metal-specific differences in OXI1 action were observed. For example, OXI1 was required for the up-regulation of antioxidative defences such as catalase in leaves and Fe-superoxide dismutase in roots, following exposure to Cu, processes that may involve the MEKK1-MKK2-WRKY25 cascade. Moreover, the induction of Cu/Zn superoxide dismutases in Cu-exposed leaves was regulated by OXI1 in a manner that involves fluctuations in the expression of miRNA398. These observations contrast markedly with the responses to Cd exposure, which also involves OXI1-independent pathways but rather involves changes in components mediating intracellular communication.
authors.affiliation: Centre for Environmental Sciences, Hasselt University, 3590, Diepenbeek, Belgium. karen.smeets@uhasselt.be
authors.forename: Karen
authors.initials: K
authors.lastname: Smeets
authors.forename: Kelly
authors.initials: K
authors.lastname: Opdenakker
authors.forename: Tony
authors.initials: T
authors.lastname: Remans
authors.forename: Celine
authors.initials: C
authors.lastname: Forzani
authors.forename: Heribert
authors.initials: H
authors.lastname: Hirt
authors.forename: Jaco
authors.initials: J
authors.lastname: Vangronsveld
authors.forename: Ann
authors.initials: A
authors.lastname: Cuypers
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000378:metabolism; D020935:MAP Kinase Signaling System; D035683:MicroRNAs / Q000378:metabolism; D010084:Oxidation-Reduction; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D016166:Free Radical Scavengers; D035683:MicroRNAs; D002104:Cadmium; D003300:Copper; D002374:Catalase; D013482:Superoxide Dismutase; C482589:OXI1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases