JXB Advance Access originally published online on July 2, 2009
Journal of Experimental Botany 2009 60(13):3727-3735; doi:10.1093/jxb/erp219
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© 2009 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RESEARCH PAPER |
OXI1 protein kinase is required for plant immunity against Pseudomonas syringae in Arabidopsis
1Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch 7701, South Africa
2Plant Stress Signalling Laboratory, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK
* Present address and to whom correspondence should be sent: Warwick HRI and Warwick Systems Biology Centre, University of Warwick, Wellesbourne, Warwick CV35 9EF, UK. E-mail: k.j.denby{at}warwick.ac.uk
Expression of the Arabidopsis Oxidative Signal-Inducible1 (OXI1) serine/threonine protein kinase gene (At3g25250) is induced by oxidative stress. The kinase is required for root hair development and basal defence against the oomycete pathogen Hyaloperonospora parasitica, two separate H2O2-mediated processes. In this study, the role of OXI1 during pathogenesis was characterized further. Null oxi1 mutants are more susceptible to both virulent and avirulent strains of the biotrophic bacterial pathogen Pseudomonas syringae compared with the wild type, indicating that OXI1 positively regulates both basal resistance triggered by the recognition of pathogen-associated molecular patterns, as well as effector-triggered immunity. The level of OXI1 expression appears to be critical in mounting an appropriate defence response since OXI1 overexpressor lines also display increased susceptibility to biotrophic pathogens. The induction of OXI1 after P. syringae infection spatially and temporally correlates with the oxidative burst. Furthermore, induction is reduced in atrbohD mutants and after application of DPI (an inhibitor of NADPH oxidases) suggesting that reactive oxygen species produced through NADPH oxidases drives OXI1 expression during this plant–pathogen interaction.
Key words: Hyaloperonospora parasitica, plant defence, Pseudomonas syringae, reactive oxygen species, signal transduction
Received 26 March 2009; Revised 11 June 2009 Accepted 12 June 2009