2018 Fiscal Year Final Research Report
Rhizobial protein secretion systems regulating symbiotic interaction with soybean
| Project/Area Number |
15K20868
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Applied molecular and cellular biology
Applied microbiology
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Research Collaborator |
MINAMISAWA Kiwamu
UMEHARA Yosuke
SUZUKI Yuta
IWANO Hiroya
TAKAHASHI Satoko
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| Project Period (FY) |
2015-04-01 – 2019-03-31
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| Keywords | 根粒菌 / タンパク質分泌系 / ダイズ / エフェクター |
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| Outline of Final Research Achievements |
In this study, we revealed that a rhizobial type III-secretory protein NopP is a causal factor of symbiotic incompatibility with Rj2-genotype soybean plants. The analysis of nopP mutations and variants in a culture collection reveal that three amino acid residues (R60, R67, and H173) in NopP are required for Rj2-mediated incompatibility. Complementation of rj2-soybean by the Rj2 allele confers the incompatibility induced by USDA122-type NopP. In response to incompatible strains, Rj2-soybean plants activate defense marker gene PR-2 and suppress infection thread number at two days after inoculation. These results suggest that Rj2-soybeans monitor the specific variants of NopP and reject bradyrhizobial infection via effector-triggered immunity mediated by Rj2 protein. In addition, the results of a mutational analysis suggest that the bradyrhizobial Type VI secretion system may be involved in the maturation of nitrogen-fixing nodules.
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| Free Research Field |
応用微生物学
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| Academic Significance and Societal Importance of the Research Achievements |
根粒菌とマメ科植物の共生相互作用における宿主特異性に3型分泌エフェクターが関与することが知られていたが、本成果から、エフェクターとNBS-LRR型抵抗性タンパク質を介した免疫系「エフェクター誘導性免疫」が機能していることを初めて実験的に示すことができた。さらにRj2タンパク質によるNopPの認識機構が、植物と病原菌の相互作用には例のないメカニズムで制御されている可能性が考えられることから、病原菌の認識機構の理解への貢献が期待される。また本成果は、根粒共生の共進化と、優良な根粒菌を利用したダイズ増収への応用技術の開発につながる重要な知見となりうる。
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