title: The Arabidopsis gain-of-function mutant dll1 spontaneously develops lesions mimicking cell death associated with disease.
abstract: We describe the characterization of a novel gain-of-function Arabidopsis mutant, dll1 (disease-like lesions1), which spontaneously develops lesions mimicking bacterial speck disease and constitutively expresses biochemical and molecular markers associated with pathogen infection. Despite the constitutive expression of defense-related responses, dll1 is unable to suppress the growth of virulent pathogens. However, dll1 elicits normal hypersensitive response in response to avirulent pathogens, thus indicating that dll1 is not defective in the induction of normal resistance responses. The lesion+ leaves of dll1 support the growth of hrcC mutant of Pseudomonas syringae, which is defective in the transfer of virulence factors into the plant cells, and therefore non-pathogenic to wild-type Col-0 plants. This suggests that dll1 intrinsically expresses many of the cellular processes that are required for pathogen growth during disease. Epistasis analyses reveal that salicylic acid and NPR1 are required for lesion formation, while ethylene modulates lesion development in dll1, suggesting that significant overlap exist between the signalling pathways leading to resistance- and disease-associated cell death. Our results suggest that host cell death during compatible interactions, at least in part, is genetically controlled by the plant and DLL1 may positively regulate this process.
authors.affiliation: Biology Department, Biotechnology Institute, and Intercollege Graduate Program in Plant Physiology, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Pilloff
authors.forename: Sendil K
authors.initials: SK
authors.lastname: Devadas
authors.forename: Alexander
authors.initials: A
authors.lastname: Enyedi
authors.forename: Ramesh
authors.initials: R
authors.lastname: Raina
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D015415:Biomarkers; D003433:Crosses, Genetic; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011549:Pseudomonas / Q000254:growth & development; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D015415:Biomarkers; D005030:Ethylenes; C105496:NPR1 protein, Arabidopsis; D010940:Plant Proteins; C036216:ethylene; D020156:Salicylic Acid