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First published online June 15, 2007; 10.1104/pp.107.099226 Plant Physiology 144:1863-1877 (2007) © 2007 American Society of Plant Biologists OPEN ACCESS ARTICLE
Resistance to Botrytis cinerea in sitiens, an Abscisic Acid-Deficient Tomato Mutant, Involves Timely Production of Hydrogen Peroxide and Cell Wall Modifications in the Epidermis1,[C],[W],[OA] a2Laboratory of Phytopathology (B.A., K.C., S.C.F., K.A., M.H.) and Department of Molecular Genetics (B.A., K.C., M.V., F.V.B.), Ghent University, B–9000 Ghent, Belgium; and Department of Plant Systems Biology, Flanders Institute for Biotechnology, B–9052 Ghent, Belgium (B.A., K.C., M.V., F.V.B.)
Plant defense mechanisms against necrotrophic pathogens, such as Botrytis cinerea, are considered to be complex and to differ from those that are effective against biotrophs. In the abscisic acid-deficient sitiens tomato (Solanum lycopersicum) mutant, which is highly resistant to B. cinerea, accumulation of hydrogen peroxide (H2O2) was earlier and stronger than in the susceptible wild type at the site of infection. In sitiens, H2O2 accumulation was observed from 4 h postinoculation (hpi), specifically in the leaf epidermal cell walls, where it caused modification by protein cross-linking and incorporation of phenolic compounds. In wild-type tomato plants, H2O2 started to accumulate 24 hpi in the mesophyll layer and was associated with spreading cell death. Transcript-profiling analysis using TOM1 microarrays revealed that defense-related transcript accumulation prior to infection was higher in sitiens than in wild type. Moreover, further elevation of sitiens defense gene expression was stronger than in wild type 8 hpi both in number of genes and in their expression levels and confirmed a role for cell wall modification in the resistant reaction. Although, in general, plant defense-related reactive oxygen species formation facilitates necrotrophic colonization, these data indicate that timely hyperinduction of H2O2-dependent defenses in the epidermal cell wall can effectively block early development of B. cinerea.
1 This work was supported by the Research Fund of Ghent University (Geconcerteerde Onderzoeksacties grant no. 12051403), the "Fonds voor Wetenschappelijk Onderzoek-Vlaanderen" (grant nos. G.0350.04 and G.0061.03), and the "Instituut voor de Aanmoediging van Innovatie door wetenschap en Technologie in Vlaanderen" (predoctoral fellowship to K.C.). 2 These authors contributed equally to the article. 3 Present address: Department of Biosciences and Landscape Architecture, University College Ghent, Voskenslaan 270, B–9000 Ghent, Belgium. 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: Monica Höfte (monica.hofte{at}ugent.be). [C] Some figures in this article are displayed in color online but in black and white in the print edition. [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.107.099226 * Corresponding author; e-mail monica.hofte{at}ugent.be; fax 32–9–264–62–38. Received March 12, 2007; accepted June 6, 2007; published June 15, 2007. This article has been cited by other articles:
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