| Project/Area Number |
08454260
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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 |
植物生理
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| Research Institution | Osaka City University |
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Principal Investigator |
HOSON Takayuki Osaka City Univ., Dept.Biology, Associate Professor, 理学部, 助教授 (70135771)
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| Co-Investigator(Kenkyū-buntansha) |
WAKABAYASHI Kazuyuki Osaka City Univ., Dept.Biology, Lecturer, 理学部, 講師 (10220831)
KAMISAKA Seiichiro Osaka City Univ., Dept.Biology, Professor, 理学部, 教授 (60047214)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1998: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1997: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1996: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Keywords | Apoplast / Azuki epicotyl / Cell wall / Environmental signal / (1*3), (1*4)-beta-glucan / Growth regulation / Rice coleoptile / Xyloglucan / 重力 / 光 / 成長 / イネ / 幼葉鞘 / エキソグルカナーゼ / エンドグルカナーゼ / 単子葉イネ科植物 / アズキ / エンド型転移酵素 |
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| Research Abstract |
Processes of the synthesis and breakdown of plant cell wall polysaccharides should be clarified in order to understand the mechanism of regulation of plant growth. From preliminary results, we hypothesized that matrix polysaccharides of plant cell wall are synthesized and degraded by a two-step process via intermediate products with a medial size. In the present study we analyzed the metabolism of two major matrix polysaccharides, xyloglucans and (1 * 3), (1 * 4) -beta-glucans, and obtained the data supporting this hypothesis.
1. From the analysis with HPLC and GLG of products by a reaction of xyloglucans and (1 * 3), (1 * 4)-beta-glucans with crude cell wall enzymes, it was shown that the polysaceharides with an intermediate size were produced under certain conditions. The size of the intermediate polysaccharides was about 50 kDa for xyloglucans and was higher than 100 kDa for (1 * 3), (1 * 4)-beta-glucans.
2. Xyloglucan hydrolases responsible for the first step of xyloglucan breakdown
… More
were purified from the cell wall of azuki bean epicotyls and characterized. They were found to belong to endo xyloglucan-transferase (EXT) family in molecular structure. However, one enzyme purified catalyzed only hydrolysis and the other showed the endo-transferase activity only under limited conditions. An alpha-fucosidase capable of triggering the second step of xyloglucan breakdown was also purified from the cell wall of azuki bean epicotyls.
3. Two types of (1 * 3), (1 * 4)-beta-glucanases were purified from the cell wall of rice coleoptiles. One enzyme showed an endoglucanase activity and appears to be involved in the first step of the breakdown of the glucans. The second step of the breakdown may be performed by an exoglucanase.
4. Both gravity and light suppressed activities of xyloglucan hydrolases and (1 * 3), (1 * 4)-beta-glucanases. Such a decrease in enzyme activities may bring about the increase in molecular size of these polvsaccharides, leading to the decrease in the wall extensibility, thereby suppressing plant growth. Less
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