2001 Fiscal Year Final Research Report Summary
Genome rearrangements of indigenous soybean bradyrhizobia and their ecological significance
| Project/Area Number |
10460028
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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 |
Plant nutrition/Soil science
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| Research Institution | Tohoku University |
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Principal Investigator |
MINAMISAWA Kiwamu Graduate School of Life Sciences, Tohoku University, Professor, 大学院・生命科学研究科, 教授 (70167667)
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| Co-Investigator(Kenkyū-buntansha) |
TSUDA Masataka Graduate School of Life Sciences, Tohoku University, Professor, 大学院・生命科学研究科, 教授 (90172022)
MITSUI Hisayuki Graduate School of Life Sciences, Tohoku University, Associate Professor, 大学院・生命科学研究科, 助教授 (40261466)
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| Project Period (FY) |
1998 – 2001
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| Keywords | Bradyrhizobium japonicum / genetic ecology / insertion sequence / nodulation / soil bacteria / soybean / stress resistance |
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| Research Abstract |
In order to understand the generation and ecological roles of Bradyrhizobium japonicum HRS strains possessing high copy numbers of insertion sequences (IS), we have investigated (1) geographical and phylogenetic distributions of HRS strains, (2) their excellent features in field ecosystem, (3) their genome rearrangements, and (4) horizontal transfer of nodulation (nod) gene from HRS strains. We found a correlation among the IS copy number, phylogenetic position, serogroup and growth rate of HRS strains, which are derived from USA, China and Japan. Nodule occupancy of HRS strains increased in a water-logged soil condition. Moreover, HRS strains showed stress resistance. The nif gene cluster of HRS strain were subjected to DNA rearrangement probably by IS elements. We have observed horizontal transfer of nod genes from B. japonicum HRS strain to B. elkanii USDA94 mutant lacking common nod genes as a recipient. In this project, we could show the ecological and genetic features of B. japonicum HRS strains.
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