title: Functional analysis of oxidative stress-activated mitogen-activated protein kinase cascade in plants.
abstract: Despite the recognition of H(2)O(2) as a central signaling molecule in stress and wounding responses, pathogen defense, and regulation of cell cycle and cell death, little is known about how the H(2)O(2) signal is perceived and transduced in plant cells. We report here that H(2)O(2) is a potent activator of mitogen-activated protein kinases (MAPKs) in Arabidopsis leaf cells. Using epitope tagging and a protoplast transient expression assay, we show that H(2)O(2) can activate a specific Arabidopsis mitogen-activated protein kinase kinase kinase, ANP1, which initiates a phosphorylation cascade involving two stress MAPKs, AtMPK3 and AtMPK6. Constitutively active ANP1 mimics the H(2)O(2) effect and initiates the MAPK cascade that induces specific stress-responsive genes, but it blocks the action of auxin, a plant mitogen and growth hormone. The latter observation provides a molecular link between oxidative stress and auxin signal transduction. Finally, we show that transgenic tobacco plants that express a constitutively active tobacco ANP1 orthologue, NPK1, display enhanced tolerance to multiple environmental stress conditions without activating previously described drought, cold, and abscisic acid signaling pathways. Thus, manipulation of key regulators of an oxidative stress signaling pathway, such as ANP1/NPK1, provides a strategy for engineering multiple stress tolerance that may greatly benefit agriculture.
authors.affiliation: Department of Genetics, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Kovtun
authors.forename: W L
authors.initials: WL
authors.lastname: Chiu
authors.forename: G
authors.initials: G
authors.lastname: Tena
authors.forename: J
authors.initials: J
authors.lastname: Sheen
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D002453:Cell Cycle / Q000502:physiology; D004789:Enzyme Activation; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D006861:Hydrogen Peroxide / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000096:biosynthesis / Q000378:metabolism; D020935:MAP Kinase Signaling System; D018384:Oxidative Stress; D010940:Plant Proteins / Q000096:biosynthesis; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic; D011523:Protoplasts / Q000378:metabolism; D015398:Signal Transduction; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D010940:Plant Proteins; D014867:Water; D006861:Hydrogen Peroxide; C108211:ANP1 kinase; D020930:MAP Kinase Kinase Kinases; C082276:NPK1 protein, Nicotiana tabacum