| Project/Area Number |
11640648
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物生理
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| Research Institution | NARA INSTITUTE OF SCIENCE AND TECHNOLOGY |
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Principal Investigator |
SHIKANAI Toshiharu Nara Institute of Science and Technology, Graduate School of Biological Sciences, Associate Professor, バイオサイエンス研究科, 助教授 (70273852)
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| Project Period (FY) |
1999 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2000: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | photosynthesis / photosynthetic electron flow / CO2 / chloroplast / photoinhibition / chlorophyll fluorescence / Arabidopsis / genetics / 光科学系I / 変異株 / シロイヌナズナ / 光化学系I / 活性酸素 / 乾燥ストレス / 酸化ストレス / Arabidopsis thaliana / 突然変異 / カロテノイド / カロチノイド / 突然変異株 |
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| Research Abstract |
The plants in the field often encounter low concentration of CO2 in the Chloroplast by the stomata closure responding to the drought stress. Absorbance of light energy under the conditions leads to the generation of active oxygen species, causing photoinhibition. Plants have multiple mechanisms to avoid photoinhibition under the low CO2 conditions. In this project we have modified the chlorophyll fluorescence imaging system to facilitate the isolation of Arabidopsis mutant defective in the dissipation of excessive light energy safely as heat (thermal dissipation). We identified mutants allelic to npq2 and npq4 which are defective in the machinery of thermal dissipation. The results confirmed the physiological significance of thermal dissipation to alleviate the stress of low CO2 concentration.
Arabidopsis mutant pgr5 was isolated depending on the defect to induce thermal dissipation at high light intensity. Pgr5 also cannot induce thermal dissipation in the CO2-free air. Pgr5 is defective in the activity of cyclic electron flow around PSI. The physiological function has been unclear for long and the gene PGR5 participates in the pathway was first identified. The PGR5-dependent cyclic electron flow around PSI is essential to protect photosynthetic machineries under low CO2 concentration conditions.
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