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- Title
The phytotoxin coronatine induces light-dependent reactive oxygen species in tomato seedlings.
- Authors
Ishiga, Yasuhiro; Uppalapati, Srinivasa Rao; Ishiga, Takako; Elavarthi, Sathya; Martin, Bjorn; Bender, Carol L.
- 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 ( FV/ FM). 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.
- Subjects
PHYTOTOXINS; TOMATOES; PSEUDOMONAS syringae; SEEDS; CELL death; GENE expression in plants; PLANT enzymes; PHOTOSYNTHESIS; PLANT inoculation; CHLOROPHYLL
- Publication
New Phytologist, 2009, Vol 181, Issue 1, p147
- ISSN
0028-646X
- Publication type
Article
- DOI
10.1111/j.1469-8137.2008.02639.x