title: Ethylene is one of the key elements for cell death and defense response control in the Arabidopsis lesion mimic mutant vad1.
abstract: Although ethylene is involved in the complex cross talk of signaling pathways regulating plant defense responses to microbial attack, its functions remain to be elucidated. The lesion mimic mutant vad1-1 (for vascular associated death), which exhibits the light-conditional appearance of propagative hypersensitive response-like lesions along the vascular system, is a good model for studying the role of ethylene in programmed cell death and defense. Here, we demonstrate that expression of genes associated with ethylene synthesis and signaling is enhanced in vad1-1 under lesion-promoting conditions and after plant-pathogen interaction. Analyses of the progeny from crosses between vad1-1 plants and either 35SERF1 transgenic plants or ein2-1, ein3-1, ein4-1, ctr1-1, or eto2-1 mutants revealed that the vad1-1 cell death and defense phenotypes are dependent on ethylene biosynthesis and signaling. In contrast, whereas vad1-1-dependent increased resistance was abolished by ein2, ein3, and ein4 mutations, positive regulation of ethylene biosynthesis (eto2-1) or ethylene responses (35SERF1) did not exacerbate this phenotype. In addition, VAD1 expression in response to a hypersensitive response-inducing bacterial pathogen is dependent on ethylene perception and signaling. These results, together with previous data, suggest that VAD1 could act as an integrative node in hormonal signaling, with ethylene acting in concert with salicylic acid as a positive regulator of cell death propagation.
authors.affiliation: Laboratoire des Interactions Plantes-Microorganismes, UMR INRA/CNRS 441/2594, 31320 Castanet-Tolosan, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bouchez
authors.forename: Carine
authors.initials: C
authors.lastname: Huard
authors.forename: Séverine
authors.initials: S
authors.lastname: Lorrain
authors.forename: Dominique
authors.initials: D
authors.lastname: Roby
authors.forename: Claudine
authors.initials: C
authors.lastname: Balagué
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D016923:Cell Death / Q000502:physiology*; D005030:Ethylenes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D044224:Pseudomonas syringae / Q000502:physiology; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D005030:Ethylenes; C525278:VAD1 protein, Arabidopsis; C036216:ethylene