| Project/Area Number |
16208008
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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 |
Plant nutrition/Soil science
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| Research Institution | Hokkaido University |
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Principal Investigator |
OSAKI Mitsuru Hokkaido University, Research Faculty of Agriculture, Professor, 大学院農学研究院, 教授 (60168903)
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| Co-Investigator(Kenkyū-buntansha) |
SHINANO Takuro Hokkaido University, Research Faculty of Agriculture, Associate Professor, 大学院農学研究院, 助教授 (20235542)
WATANABE Toshihiro Hokkaido University, Research Faculty of Agriculture, Assistant Professor, 大学院農学研究院, 助手 (60360939)
KOYAMA Hiroyuki Gifu University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (90234921)
TAWARAYA Keitaro Yamagata University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (70179919)
WASAKI Jun Hokkaido University, Creative Research Initiative 'Sousei' (CRIS), Associate Professor, 特任助教授 (00374728)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥40,040,000 (Direct Cost: ¥30,800,000、Indirect Cost: ¥9,240,000)
Fiscal Year 2006: ¥9,750,000 (Direct Cost: ¥7,500,000、Indirect Cost: ¥2,250,000)
Fiscal Year 2005: ¥13,650,000 (Direct Cost: ¥10,500,000、Indirect Cost: ¥3,150,000)
Fiscal Year 2004: ¥16,640,000 (Direct Cost: ¥12,800,000、Indirect Cost: ¥3,840,000)
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| Keywords | Acid Soil / Root Exudates / Secretory Protein / Organic Acids / Aluminum / Mucilage / Arbuscular Mycorrhiza / Phosphorus / 根圏 |
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| Research Abstract |
This study aimed to solve problems on acid soils for utilization as arable soils. Critical problems of acid soil are 1) toxicity of metallic ions and 2) phosphorus starvation. Some plant species have been developed some strategies to adapt on acid soils. We have shown that the several root exudates bring the tolerance to stresses on acid soils. Therefore, the secreting abilities of plant roots were investigated in this study.
A gene for secretory acid phosphatase isolated from white lupin, which is well known as a phosphorus tolerative plant, was introduced into tobacco plants. The growth and phosphorus acquisition of transgenic plant were improved from wild type plants. To investigate the secreting ability of organic acid, which can liberate inorganic phosphate from sparingly soluble forms, malate exudation of Arabidopsis was chosen as a model. It was indicated that malate release was induced by the up-regulation of malate transporter protein. The induction of malate transporter expres
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sion by aluminum was specific in the root tips and internal tissues of roots, suggesting that the mechanism is regulated to minimize the carbon consumption. It is concluded that site-specific regulation of the transporters is required to improve the inorganic phosphate uptake ability.
It was suggested that the specificities of mucilage, consisted of polysaccharides, in the root exudates differed among plant species. The highest affinities of mucilage of Melastoma malabathricum and maize were shown with trivalent and divalent cations, respectively. The affinity of mucilage of Melastoma malabathricum was high to aluminum ion, though the binding strength was quite lower than that of maize. It was supposed that not only the composition of sugar but also methylation of uronic acids were involved in the differences of adsorption specificity to the cation. Separation and purification of substances involved in the elongation of mycorrhizal hyphae was conducted. It was succeeded that an A2 fraction, which induced an elongation and secondary and further branching of mycorrhizal hyphae was obtained from root exudates of onion. Less
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