The phytotoxin coronatine induces light-dependent reactive oxygen species in tomato seedlings.
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.
Ishiga
Yasuhiro
Y
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.
Uppalapati
Srinivasa Rao
SR
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.
Ishiga
Takako
T
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.
Elavarthi
Sathya
S
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.
Martin
Bjorn
B
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.
Bender
Carol L
CL
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.
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
D000596:Amino Acids; D007192:Indenes; D017382:Reactive Oxygen Species; C058487:coronatine