title: The phytotoxin coronatine induces light-dependent reactive oxygen species in tomato seedlings.
abstract: The phytotoxin coronatine (COR), which is produced by Pseudomonas syringae pv. tomato DC3000 (DC3000), has multiple roles in virulence that lead to chlorosis and a reduction in chlorophyll content. However, the physiological significance of COR-induced chlorosis in disease development is still largely unknown. Global expression analysis demonstrated that DC3000 and COR, but not the COR-defective mutant DB29, caused reduced expression of photosynthesis-related genes and result in a 1.5- to 2-fold reduction in maximum quantum efficiency of photosystem II (F(V)/F(M)). Tomato (Solanum lycopersicum) seedlings inoculated with DC3000 and incubated in a long daily photoperiod showed more necrosis than inoculated seedlings incubated in either dark or a short daily photoperiod. The accumulation of reactive oxygen species (ROS) was detected in cotyledons inoculated with either purified COR or DC3000 but not in tissues inoculated with DB29. Interestingly, COR-induced ROS accumulated only in light and was inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and diphenylene iodonium, which function to inhibit electron transport from PSII. Furthermore, COR and DC3000 suppressed expression of the gene encoding the thylakoid Cu/Zn superoxide dismutase but not the cytosolic form of the same enzyme. In conclusion, these results demonstrate a role for COR-induced effects on photosynthetic machinery and ROS in modulating necrotic cell death during bacterial speck disease of tomato.
authors.affiliation: 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA;Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;480 Agricultural Hall, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishiga
authors.affiliation: 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA;Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;480 Agricultural Hall, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Srinivasa Rao
authors.initials: SR
authors.lastname: Uppalapati
authors.affiliation: 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA;Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;480 Agricultural Hall, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Takako
authors.initials: T
authors.lastname: Ishiga
authors.affiliation: 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA;Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;480 Agricultural Hall, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Sathya
authors.initials: S
authors.lastname: Elavarthi
authors.affiliation: 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA;Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;480 Agricultural Hall, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Bjorn
authors.initials: B
authors.lastname: Martin
authors.affiliation: 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA;Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;480 Agricultural Hall, Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Carol L
authors.initials: CL
authors.lastname: Bender
mesh_terms: D000596:Amino Acids / Q000633:toxicity*; D016923:Cell Death; D002736:Chloroplasts; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D007192:Indenes / Q000633:toxicity*; D008027:Light; D018551:Solanum lycopersicum / Q000378:metabolism / Q000382:microbiology* / Q000502:physiology; D010788:Photosynthesis / Q000235:genetics* / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology; D044224:Pseudomonas syringae / Q000472:pathogenicity*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D036226:Seedlings
chemical_list: D000596:Amino Acids; D007192:Indenes; D017382:Reactive Oxygen Species; C058487:coronatine