title: A permeable cuticle is associated with the release of reactive oxygen species and induction of innate immunity.
abstract: Wounded leaves of Arabidopsis thaliana show transient immunity to Botrytis cinerea, the causal agent of grey mould. Using a fluorescent probe, histological staining and a luminol assay, we now show that reactive oxygen species (ROS), including H(2)O(2) and O(2) (-), are produced within minutes after wounding. ROS are formed in the absence of the enzymes Atrboh D and F and can be prevented by diphenylene iodonium (DPI) or catalase. H(2)O(2) was shown to protect plants upon exogenous application. ROS accumulation and resistance to B. cinerea were abolished when wounded leaves were incubated under dry conditions, an effect that was found to depend on abscisic acid (ABA). Accordingly, ABA biosynthesis mutants (aba2 and aba3) were still fully resistant under dry conditions even without wounding. Under dry conditions, wounded plants contained higher ABA levels and displayed enhanced expression of ABA-dependent and ABA-reporter genes. Mutants impaired in cutin synthesis such as bdg and lacs2.3 are already known to display a high level of resistance to B. cinerea and were found to produce ROS even when leaves were not wounded. An increased permeability of the cuticle and enhanced ROS production were detected in aba2 and aba3 mutants as described for bdg and lacs2.3. Moreover, leaf surfaces treated with cutinase produced ROS and became more protected to B. cinerea. Thus, increased permeability of the cuticle is strongly linked with ROS formation and resistance to B. cinerea. The amount of oxalic acid, an inhibitor of ROS secreted by B. cinerea could be reduced using plants over expressing a fungal oxalate decarboxylase of Trametes versicolor. Infection of such plants resulted in a faster ROS accumulation and resistance to B. cinerea than that observed in untransformed controls, demonstrating the importance of fungal suppression of ROS formation by oxalic acid. Thus, changes in the diffusive properties of the cuticle are linked with the induction ROS and attending innate defenses.
authors.affiliation: Department of Biology, University of Fribourg, Fribourg, Switzerland.
authors.forename: Floriane
authors.initials: F
authors.lastname: L'Haridon
authors.forename: Angélique
authors.initials: A
authors.lastname: Besson-Bard
authors.forename: Matteo
authors.initials: M
authors.lastname: Binda
authors.forename: Mario
authors.initials: M
authors.lastname: Serrano
authors.forename: Eliane
authors.initials: E
authors.lastname: Abou-Mansour
authors.forename: Francine
authors.initials: F
authors.lastname: Balet
authors.forename: Henk-Jan
authors.initials: HJ
authors.lastname: Schoonbeek
authors.forename: Stephane
authors.initials: S
authors.lastname: Hess
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mir
authors.forename: José
authors.initials: J
authors.lastname: Léon
authors.forename: Olivier
authors.initials: O
authors.lastname: Lamotte
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Métraux
mesh_terms: D000040:Abscisic Acid / Q000235:genetics / Q000276:immunology; D017360:Arabidopsis / Q000276:immunology / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology; D020171:Botrytis / Q000276:immunology*; D002262:Carboxy-Lyases / Q000235:genetics / Q000276:immunology; D003066:Coenzyme A Ligases / Q000235:genetics / Q000276:immunology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000276:immunology*; D008563:Membrane Lipids / Q000235:genetics / Q000276:immunology; D009154:Mutation / Q000276:immunology; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D057865:Plant Immunity / Q000502:physiology*; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D013481:Superoxides / Q000276:immunology*; D055454:Trametes / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; C512167:BDG protein, Arabidopsis; D005656:Fungal Proteins; D008563:Membrane Lipids; D013481:Superoxides; C000521:cutin; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D002262:Carboxy-Lyases; C021915:oxalate decarboxylase; D003066:Coenzyme A Ligases; C523086:LACS2 protein, Arabidopsis