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First published online September 12, 2008; 10.1104/pp.108.127845 Plant Physiology 148:1695-1706 (2008) © 2008 American Society of Plant Biologists OPEN ACCESS ARTICLE
The AtrbohD-Mediated Oxidative Burst Elicited by Oligogalacturonides in Arabidopsis Is Dispensable for the Activation of Defense Responses Effective against Botrytis cinerea1,[W],[OA]Dipartimento di Biologia Vegetale, Università di Roma "La Sapienza," 5–00185 Rome, Italy (R.G., G.D.L., S.F.); Dipartimento Territorio e Sistemi Agro-Forestali, Università degli Studi di Padova, 35020 Legnaro, Italy (S.G.); and Department of Genetics, Harvard Medical School, and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114 (C.D., J.D., F.M.A.)
Oligogalacturonides (OGs) are endogenous elicitors of defense responses released after partial degradation of pectin in the plant cell wall. We have previously shown that, in Arabidopsis (Arabidopsis thaliana), OGs induce the expression of PHYTOALEXIN DEFICIENT3 (PAD3) and increase resistance to the necrotrophic fungal pathogen Botrytis cinerea independently of signaling pathways mediated by jasmonate, salicylic acid, and ethylene. Here, we illustrate that the rapid induction of the expression of a variety of genes by OGs is also independent of salicylic acid, ethylene, and jasmonate. OGs elicit a robust extracellular oxidative burst that is generated by the NADPH oxidase AtrbohD. This burst is not required for the expression of OG-responsive genes or for OG-induced resistance to B. cinerea, whereas callose accumulation requires a functional AtrbohD. OG-induced resistance to B. cinerea is also unaffected in powdery mildew resistant4, despite the fact that callose accumulation was almost abolished in this mutant. These results indicate that the OG-induced oxidative burst is not required for the activation of defense responses effective against B. cinerea, leaving open the question of the role of reactive oxygen species in elicitor-mediated defense.
1 This work was supported by the Ministero dell'Università e della Ricerca (grant no. PRIN2006), by the European Union (grant no. 23044 ["Nutra-Snacks"] to S.F.), by the Ministero dell'Università e della Ricerca (grant no. PRIN 2005) and ERA-NET Plant Genomics (grant no. RBER063SN4) to G.D.L., and by the National Institutes of Health (grant no. GM48707) and the National Science Foundation (grant no. DBI–0114783) to F.M.A. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Simone Ferrari (simone.ferrari{at}uniroma1.it). [W] The online version of this article contains Web-only data. [OA] Open Access articles can be viewed online without a subscription. www.plantphysiol.org/cgi/doi/10.1104/pp.108.127845 * Corresponding author; e-mail simone.ferrari{at}uniroma1.it. Received August 8, 2008; accepted September 7, 2008; published September 12, 2008. This article has been cited by other articles:
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