| Project/Area Number |
07406017
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物保護
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| Research Institution | Tamagawa University |
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Principal Investigator |
WAKABAYASHI Ko Faculty of Agriculture, Tamagawa University, Professor, 農学部, 教授 (00220830)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Yukiharu Faculty of Agriculture, Tamagawa University, Professor, 農学部, 教授 (40119516)
KOHNO Hitoshi Faculty of Agriculture, Tamagawa University, Professor, 農学部, 教授 (40074356)
HIRAI Kenji Sagami Chemical Reseach Center, Chief Scientist, 主任研究員
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1996: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Peroxidizing phytotoxicities / Active oxygen / Protoporphyrinogen-IX oxidase (Protox) / Destruction of thylakoid membranes / Chemiluminescence using isoluminol / Cyclic imides / Diphenyl ethers / Protox inhibitors / 活性酸素 |
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| Research Abstract |
Phytotoxic diphenyl ethers and cyclic imides induce inhibition of chlorophyll biosynthesis and photooxidative destruction of plant membranes affecting photosynthetic pigment contents. A peroxidizing mechanism of action of the compounds has been proposed already in our precedent study befor staring this Grant-In-Aid Research. The immediate physiological response of plants against the peroxidizing compounds is a halt of chlorophyll biosynthesis in chloroplasts by specific inhibition of protoporphyrinogen-IX oxidase. This inhibition is accompanied by an abnormal accumulation of tetrapyrroles. Protoporphyrin-IX,the main tetrapyrrole intermediate accumulated, acts as a photosensitizer in the light and induces radical formation with subsequent destruction of cellular constituents. Decrease of photosynthetic pigments, chlorophylls and caroteoids, quite well correlates not only ethane formation caused by destruction of thylakoid membranes, but also protoporphyrinogen-IX oxidase inhibition by the peroxidizing compounds. However, it was not fully elucidated yet in our proposal how the starting radicals for peroxidizing process were formed. This research was conducted to establish and confirm radical reactions involved in active oxygen, to elucidate oxidative destruction of thylakoid membranes.
Results obtained (1-3) are now quite well explaining the complicated radical reactions from protoporphyrin-IX accumulation to ethane formation as well as decrease of photosynthetic pigments (see references, the details).
(1) Protoporphyrinogen-IX oxidase inhibitors accumulated tetrapyrroles and induced ethane formation, causing (thlakoid)-membrane destruction.
(2) Photosynthetic electron transport inhibitors allviated ethane formation.
(3) In peroxidizing reaction, lipid-hydroperoxides were determined using HPLC-System combined with isoluminolchemiluminescence, thus confirming radical reactions in the process.
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