1999 Fiscal Year Final Research Report Summary
Functions of plant hormones involved in the formation of nodules on the roots of legumes
| Project/Area Number |
10660105
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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 |
Bioproduction chemistry/Bioorganic chemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
YAMANE Hisakazu Biotechnology Research Center ; The University of Tokyo, Professor, 生物生産工学研究センター, 教授 (80090520)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Glycine max L. / Bradyrhizobium elkanii / transposon / indole-3-acetic acid / indole-3-pyruvate decarboxylase / jasmonic acid / flavonoids / phenylalanine ammonia-lyase |
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| Research Abstract |
We have isolated the 11 low-indole-3-acetic acid (IAA)-producing mutants of Bradyrhizobium elkanii by Tn5 mutagenesis. The amounts of IAA produced by the respective mutants were 2.2 to 13.6 % of that in the wild type. It was also shown by resting cell reactions that biosynthetic step to convert indole-3-pyrubic acid to indole-3-acetaldehyde was blocked in all the mutants. This suggests that indole-3-pyruvate decarboxylase (IPDC) functions as a key enzyme in the IAA biosynthesis of B. elkanii. When some of the low-IAA-producing mutants were applied to the leguminous plant siratro, the number of noduration on the roots reduced 10 to 60% of that when the wild type was applied, indicating that IAA produced by B. elkanii plays impotant roles on the formation of root nodules. On the other hand, it has been shown that flavonoids secreted from the roots of host plants induced the expression of nod genes in the nodule bacteria. We speculated that nod factors causes promotion of flavonoid biosynthesis via jasmonate biosynthesisas as well as the early events of nodulation in the host plants. To investigate this hypothesis, we developed a bioassay system using suspension-cultured cells of Glycine max to examine the effect of jasmonic acid or nod factors on phenylalanine ammonia-lyase (PAL) activity, which is a key enzyme in the flavonoid biosynthesis.
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[Publications] Ken Yagi, Taku Matsumoto, Tetsuya Chujo, Hideaki Nojiri, Toshio Omori, Kiwamu Minamisawa, Makoto Nishiyama, and Hisakazu Yamane: "Isolation and characterization of low-indole-3-acetic acid-producing mutants of Bradyrhizobium elkanii"Bioscience, Biotechnology, and Biochemistry. Vol. 64, (in press). (2000)
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