| Project/Area Number |
14360010
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
作物学
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| Research Institution | Tokyo University of Agriculture and Technology |
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Principal Investigator |
HIRASAWA Tadashi National University Corporation Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Professor, 大学院・共生科学技術研究部, 教授 (30015119)
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| Co-Investigator(Kenkyū-buntansha) |
OOKAWA Taiichiro National University Corporation Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor, 大学院・共生科学技術研究部, 助教授 (80213643)
KANEKATSU Motoki National University Corporation Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor, 大学院・共生科学技術研究部, 助教授 (60177508)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥14,700,000 (Direct Cost: ¥14,700,000)
Fiscal Year 2004: ¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 2003: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 2002: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Keywords | Abscisic acid / Cytokinin / Photosynthesis / Protein kinase / Rubisco / Rubisco mRNA / Senescence / Water stress / 水ストレス応答 / シグナル伝達 / 窒素 / 窒素含量 / β-アミラーゼ / Rubisco遺伝子 |
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| Research Abstract |
Water stress enhances the reduction of the rate of leaf photosynthesis during senescence, which results in the reduction of dry matter production in crop plants under water stress. The objective of this research was undertaken to investigate molecular mechanisms of the effects of water stress on the rate of leaf photosynthesis during senescence. The followings are obtained results in the research.
(1)The reduction in leaf levels of nitrogen and ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco) was responsible for the significant reduction of the rate of leaf photosynthesis during senescence under water stress in rice plants.
(2)The amount of cytokinins, especially trans-zeatin, transported from roots to shoot decreased significantly in rice plants under water stress and there were close correlations between the total amount of the cytokinins and the rate of leaf photosynthesis, the leaf levels of nitrogen and Rubisco.
(3)Application of additional cytokinin increased the nitrogen partitioning and the level of Rubisco mRNA (rbcL and rbcS).
(4)From the results mentioned above, it was suggested that cytokinins transported from roots to shoot might be included in the mechanisms of the enhancement of the reduction in the rate of leaf photosynthesis. The reduction in the cytokinins transport under water stress might cause the decreased portioning of nitrogen to leaves and the decreased Rubisco synthesis and/or might enhance the Rubisco decomposition.
(5)In order to elucidate the mechanism of molecular responses to water stress, the protein kinase activities were analyzed in cucumber cotyledons subjected to water stress. It has been found that ABA and salt stress, which induce the water stress responsible,-amylase, activate a 38 kDa protein kinase in cucumber cotyledons. This result suggests that the 38kDa protein kinase may play an important role in responses to water stress.
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