Regulatory mechanisms of ROI generation are affected by rice spl mutations.
Reactive oxygen intermediates (ROIs) play a pivotal role in the hypersensitive response (HR) in disease resistance. NADPH oxidase is a major source of ROI; however, the mechanisms of its regulation are unclear. Rice spl mutants spontaneously form lesions which resemble those occurring during the HR, suggesting that the mutations affect regulation of the HR. We found that spl2, spl7 and spl11 mutant cells accumulated increased amounts of H(2)O(2) in response to rice blast fungal elicitor. Increased accumulation of ROIs was suppressed by inhibition of NADPH oxidase in the spl cells, and was also observed in the ozone-exposed spl plants. These mutants have sufficient activities of ROI-scavenging enzymes compared with the wild type. In addition, spl7 mutant cells accumulated higher amounts of H(2)O(2) when treated with calyculin A (CA), an inhibitor of protein phosphatase. Furthermore, spl2 mutant plants exhibited accelerated accumulation of H(2)O(2) and increased rates of cell death in response to wounding. These results suggest that the spl2, spl7 and spl11 mutants are defective in the regulation of NADPH oxidase, and the spl7 mutation may give rise to enhancement of the signaling pathway which protein dephosphorylation controls, while the spl2 mutation affects both the pathogen-induced and wound-induced signaling pathways.
Kojo
Kaori
K
Department of Biology, Faculty of Sciences, Kyushu University, Hakozaki, Fukuoka, 812-8581 Japan.
Yaeno
Takashi
T
Kusumi
Kensuke
K
Matsumura
Hideo
H
Fujisawa
Shizuko
S
Terauchi
Ryohei
R
Iba
Koh
K
D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006967:Hypersensitivity; D008387:Marine Toxins; D009154:Mutation; D012275:Oryza / Q000166:cytology*; D010080:Oxazoles / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014947:Wounds and Injuries / Q000473:pathology
D004791:Enzyme Inhibitors; D008387:Marine Toxins; D010080:Oxazoles; D017382:Reactive Oxygen Species; D010126:Ozone; C059041:calyculin A; D006861:Hydrogen Peroxide; D010749:Phosphoprotein Phosphatases