title: Salicylic acid antagonism of EDS1-driven cell death is important for immune and oxidative stress responses in Arabidopsis.
abstract: Reactive oxygen species (ROS) have emerged as signals in the responses of plants to stress. Arabidopsis Enhanced Disease Susceptibility1 (EDS1) regulates defense and cell death against biotrophic pathogens and controls cell death propagation in response to chloroplast-derived ROS. Arabidopsis Nudix hydrolase7 (nudt7) mutants are sensitized to photo-oxidative stress and display EDS1-dependent enhanced resistance, salicylic acid (SA) accumulation and initiation of cell death. Here we explored the relationship between EDS1, EDS1-regulated SA and ROS by examining gene expression profiles, photo-oxidative stress and resistance phenotypes of nudt7 mutants in combination with eds1 and the SA-biosynthetic mutant, sid2. We establish that EDS1 controls steps downstream of chloroplast-derived O(2)(*-) that lead to SA-assisted H(2)O(2) accumulation as part of a mechanism limiting cell death. A combination of EDS1-regulated SA-antagonized and SA-promoted processes is necessary for resistance to host-adapted pathogens and for a balanced response to photo-oxidative stress. In contrast to SA, the apoplastic ROS-producing enzyme NADPH oxidase RbohD promotes initiation of cell death during photo-oxidative stress. Thus, chloroplastic O(2)(*-) signals are processed by EDS1 to produce counter-balancing activities of SA and RbohD in the control of cell death. Our data strengthen the idea that EDS1 responds to the status of O(2)(*-) or O(2)(*-)-generated molecules to coordinate cell death and defense outputs. This activity may enable the plant to respond flexibly to different biotic and abiotic stresses in the environment.
authors.affiliation: Max-Planck-Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Köln, Germany.
authors.forename: Marco R
authors.initials: MR
authors.lastname: Straus
authors.forename: Steffen
authors.initials: S
authors.lastname: Rietz
authors.forename: Emiel
authors.initials: E
authors.lastname: Ver Loren van Themaat
authors.forename: Michael
authors.initials: M
authors.lastname: Bartsch
authors.forename: Jane E
authors.initials: JE
authors.lastname: Parker
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D018384:Oxidative Stress; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological; D000096964:Nudix Hydrolases
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D006861:Hydrogen Peroxide; D011755:Pyrophosphatases; D018749:RNA, Plant; D017382:Reactive Oxygen Species; D020156:Salicylic Acid; D000096964:Nudix Hydrolases; C118837:EDS1 protein, Arabidopsis