| Project/Area Number |
18570048
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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・分子
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| Research Institution | Kyoto Prefectural University |
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Principal Investigator |
SHIINA Takashi Kyoto Prefectural University, Faculty of Human environment, Professor (10206039)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥4,020,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥420,000)
Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Ca^<2+> / stomata / CAS / chlorosplast / infection / stress / chloroplast signal / Arabidopsis / Ca^<2+> / チラコイド膜 / リン酸化 / 光 / Ca2+シグナル / 孔辺細胞 / 気孔運動 / イクオリン |
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| Research Abstract |
The role of guard cell chloroplasts in stomatal function is controversial. It is usually assumed that stomatal closure is preceded by a transient increase in cytosolic free Ca^<2+> concentration (Ca^<2+>)_<cyt>) in the guard cells. CAS (Ca^<2+> sensing receptor) is a plant-specific putative Ca^<2+>-binding protein. We foundthat CAS is an integral thylakoid membrane protein, and the N-terminus acidic Ca^<2+>-binding region is likely exposed to the stromal side of the membrane. CAS is essential for stomatal closure induced by external Ca^<2+>. These results provide the evidence that chloroplasts play a critical role in the generation of extracellular Ca^<2+>([Ca^<2+>]_<ext>)-induced[Ca^<2+>]_<cyt> transients and stomatal closure in Arabidopsis.
In addition, we founs that extracellular abiotic and pathogen-related stress signals are relayed quickly to chloroplasts, and evoke rapid and transient increases in stromal Ca^<2+> concentration in a stress-dependent manner. Furthermore we demonstrated that CAS is also related to the generation of stromal Ca2+ transients induced by pathogen elicitors and/or light to dark transition. Furthermore, we demonstrated that CAS regulates a multitude of plant innate immune responses, such as flg22-induced stomatal closure, expression of pathogen-related genes, ROS production and a resistance (R) gene-triggered hypersensitive cell death in Arabidopsis. It should be noted that cas-1 shows no significant growth phenotype. These results may have implications for a far more important role of chloroplasts in the regulation of plant innate immune response than was thought.
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