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Letters to Nature

Nature 427, 858-861 (26 February 2004) | doi:10.1038/nature02353; Received 16 August 2003; Accepted 19 January 2004

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OXI1 kinase is necessary for oxidative burst-mediated signalling in Arabidopsis

Maike C. Rentel1,6, David Lecourieux2, Fatma Ouaked2, Sarah L. Usher3, Lindsay Petersen1,4, Haruko Okamoto1, Heather Knight1, Scott C. Peck5, Claire S. Grierson3, Heribert Hirt2 & Marc R. Knight1

  1. Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
  2. Max F. Perutz Laboratories of the University of Vienna and Gregor-Mendel-Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna Biocenter, 1030 Vienna, Austria
  3. School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
  4. Department of Molecular and Cell Biology, University of Cape Town, Private Bag Rondebosch 7701, South Africa
  5. Sainsbury Laboratory, Norwich NR4 7UH, UK
  6. Present address: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143-0450, USA

Correspondence to: Maike C. Rentel1,6Heribert Hirt2 Email: mrentel@cmp.ucsf.edu
Email: heribert.hirt@univie.ac.at

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Active oxygen species (AOS) generated in response to stimuli and during development can function as signalling molecules in eukaryotes, leading to specific downstream responses1, 2. In plants these include such diverse processes as coping with stress (for example pathogen attack3, wounding4 and oxygen deprivation5), abscisic-acid-induced guard-cell closure6, and cellular development (for example root hair growth7). 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.