Abstract
Active oxygen species (AOS) generated in response to stimuli and during development can function as signalling molecules in eukaryotes, leading to specific downstream responses. In plants these include such diverse processes as coping with stress (for example pathogen attack, wounding and oxygen deprivation), abscisic-acid-induced guard-cell closure, and cellular development (for example root hair growth). Despite the importance of signalling via AOS in eukaryotes, little is known about the protein components operating downstream of AOS that mediate any of these processes. Here we show that expression of an Arabidopsis thaliana gene (OXI1) encoding a serine/threonine kinase is induced in response to a wide range of H2O2-generating stimuli. OXI1 kinase activity is itself also induced by H2O2 in vivo. OXI1 is required for full activation of the mitogen-activated protein kinases (MAPKs) MPK3 and MPK6 after treatment with AOS or elicitor and is necessary for at least two very different AOS-mediated processes: basal resistance to Peronospora parasitica infection, and root hair growth. Thus, OXI1 is an essential part of the signal transduction pathway linking oxidative burst signals to diverse downstream responses.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Arabidopsis / enzymology
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Arabidopsis / genetics
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Arabidopsis / metabolism*
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Arabidopsis / parasitology
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Cellulase / metabolism
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Enzyme Activation / drug effects
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Enzyme Induction / drug effects
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Genes, Reporter
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Genetic Complementation Test
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Hydrogen Peroxide / metabolism
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Hydrogen Peroxide / pharmacology
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MAP Kinase Signaling System* / drug effects
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Mitogen-Activated Protein Kinase Kinases / metabolism
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Mitogen-Activated Protein Kinases / metabolism
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Phytophthora / physiology
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Plant Diseases / genetics
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Plant Diseases / parasitology
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Plant Roots / enzymology
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Plant Roots / growth & development
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Plant Roots / metabolism
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Reactive Oxygen Species / metabolism
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Respiratory Burst*
Substances
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Arabidopsis Proteins
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RNA, Messenger
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Reactive Oxygen Species
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Hydrogen Peroxide
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OXI1 protein, Arabidopsis
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Protein Serine-Threonine Kinases
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ATMPK1 protein, Arabidopsis
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AtMPK3 protein, Arabidopsis
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Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinase Kinases
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Cellulase