title: Erwinia amylovora type three-secreted proteins trigger cell death and defense responses in Arabidopsis thaliana.
abstract: Erwinia amylovora is the bacterium responsible for fire blight, a necrotic disease affecting plants of the rosaceous family. E. amylovora pathogenicity requires a functional type three secretion system (T3SS). We show here that E. amylovora triggers a T3SS-dependent cell death on Arabidopsis thaliana. The plants respond by inducing T3SS-dependent defense responses, including salicylic acid (SA)-independent callose deposition, activation of the SA defense pathway, reactive oxygen species (ROS) accumulation, and part of the jasmonic acid/ethylene defense pathway. Several of these reactions are similar to what is observed in host plants. We show that the cell death triggered by E. amylovora on A. thaliana could not be simply explained by the recognition of AvrRpt2 ea by the resistance gene product RPS2. We then analyzed the role of type three-secreted proteins (T3SPs) DspA/E, HrpN, and HrpW in the induction of cell death and defense reactions in A. thaliana following infection with the corresponding E. amylovora mutant strains. HrpN and DspA/E were found to play an important role in the induction of cell death, activation of defense pathways, and ROS accumulation. None of the T3SPs tested played a major role in the induction of SA-independent callose deposition. The relative importance of T3SPs in A. thaliana is correlated with their relative importance in the disease process on host plants, indicating that A. thaliana can be used as a model to study their role.
authors.affiliation: 1Laboratoire des Interactions Plantes Pathogènes UMR 217 INRA/AgroParisTech/UPMC Paris VI, 16 rue Claude Bernard 75005 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Degrave
authors.forename: M
authors.initials: M
authors.lastname: Fagard
authors.forename: C
authors.initials: C
authors.lastname: Perino
authors.forename: M N
authors.initials: MN
authors.lastname: Brisset
authors.forename: S
authors.initials: S
authors.lastname: Gaubert
authors.forename: S
authors.initials: S
authors.lastname: Laroche
authors.forename: O
authors.initials: O
authors.lastname: Patrit
authors.forename: M-A
authors.initials: MA
authors.lastname: Barny
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000382:microbiology*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D016923:Cell Death; D003517:Cyclopentanes / Q000378:metabolism; D044084:Erwinia amylovora / Q000378:metabolism* / Q000472:pathogenicity / Q000502:physiology*; D005030:Ethylenes / Q000378:metabolism; D005936:Glucans / Q000378:metabolism; D054884:Host-Pathogen Interactions; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003517:Cyclopentanes; C110611:DspA protein, Erwinia amylovora; D005030:Ethylenes; D005936:Glucans; D054883:Oxylipins; D017382:Reactive Oxygen Species; C075462:harpin protein, Erwinia amylovora; C011006:jasmonic acid; C048306:callose; C036216:ethylene; D020156:Salicylic Acid