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Distinct Defenses Induced in Wheat Against Powdery Mildew by Acetylated and Nonacetylated Oligogalacturonides

December 2010 , Volume 100 , Number  12
Pages  1,352 - 1,363

Béatrice Randoux, Delphine Renard-Merlier, Ghislain Mulard, Stéphanie Rossard, Florent Duyme, Jean Sanssené, Josiane Courtois, Roger Durand, and Philippe Reignault

First, second, third, eighth, and ninth authors: Université Lille Nord de France, F-59000 Lille, Unité de Chimie Environnementale et Interactions sur le Vivant, GIS PhyNoPi, Université du Littoral Côte d'Opale, 17 avenue Blériot, BP 699, F-62228 Calais cedex, France; fourth and seventh authors: Laboratoire des Polysaccharides Microbiens et Végétaux, Université de Picardie Jules Verne, Avenue des Facultés, le Bailly, F-80025 Amiens cedex, France; fifth author: Arvalis-Institut du Végétal, Station Expérimentale, F-91720 Boigneville cedex, France; and sixth author: LaSalle Beauvais, GIS PhyNoPi, rue P. Waguet, BP 30313, F-60026 Beauvais cedex, France.

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Accepted for publication 23 July 2010.

In wheat, little is known about disease resistance inducers and, more specifically, about the biological activities from those derived from endogenous elicitors, such as oligogalacturonides (OGAs). Therefore, we tested the ability of two fractions of OGAs, with polymerization degrees (DPs) of 2–25, to induce resistance to Blumeria graminis f. sp. tritici and defense responses in wheat. One fraction was unacetylated (OGAs–Ac) whereas the second one was 30% chemically acetylated (OGAs+Ac). Infection level was reduced to 57 and 58% relative to controls when OGAs–Ac and OGAs+Ac, respectively, were sprayed 48 h before inoculation. Activities of various defense-related enzymes were then assayed in noninoculated wheat leaves infiltrated with OGAs. Oxalate oxidase, peroxidase, and lipoxygenase were responsive to both OGAs–Ac and OGAs+Ac, which suggests involvement of reactive oxygen species and oxilipins in OGAs-mediated responses in wheat. In inoculated leaves, both fractions induced a similar increase in H2O2 accumulation at the site of fungal penetration. However, only OGAs+Ac led to an increase in papilla-associated fluorescence and to a reduction of formed fungal haustoria. Our work provides the first evidence for elicitation and protection effects of preventive treatments with OGAs in wheat and for new properties of acetylated OGAs.

Additional keywords: induced resistance, Triticum aestivum.

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2010.