2007 Fiscal Year Final Research Report Summary
Research on the host plant genes involving symbiotic nitrogen fixation between the leguminous plants and Rhizobia
| Project/Area Number |
17570044
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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 |
植物生理・分子
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| Research Institution | National Institute of Agrobiological Sciences |
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Principal Investigator |
YOSUKE Umehara National Institute of Agrobiological Sciences, Plant-Microbe Interactions Research Unit, Chief Researcher (00391558)
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| Project Period (FY) |
2005 – 2007
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| Keywords | symbiotic nitrogen fixation / the leguminous plants / Rhizobia / Fix-mutants / Lotus japonicus |
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| Research Abstract |
The leguminous plants form root nodule for the symbiosis with soil bacteria Rhizobia to fix the atomospheric dinitrogen. Biological nitrogen fixation plays very important role for agricultural production in the world. The effective utilization of it is a major issue for the development of sustainable agricultural technology. Therefore clarification of molecular mechanism of development and maintenance of biological nitrogen fixation system is indispensable.
Recently, the host plant genes involved in the early stage signal transduction pathway of Rhizobia infection have been to identified by molecular genetics using model legumes such as Lotus japonicus and Medicago trancatula. On the other hand, the later stages of the symbiosis, infection to the root hair, release into the host plant cells, establishment of nitrogen fixation system and maintenance of nitrogen fixation activity, are to be question. In this study, a plant gene involved in the later stages of symbiosis was clarified using
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Lotus Fix-mutant Ljsym102 with the defect of nitrogen fixation activity.
Ljsym102 is a recessive and monogenic Fix-mutant which forms root nodules by Rhizobia infection but shows little nitrogenase activity. Observation of the nodule sections on 16 days post inoculation showed that nodule tissues were differentiated and the bacteria were in the infected cells. Most infected cells were deteriorated and showed granular structure. Therefore, in this mutant, nodule tissues were differentiated but. functional nitrogen fixation system was not developed.
Using BAC and TAC contigs and 1644 of F2 and F3 plants derived from crossing the mutant and Miyakojima, the gene region was focused into the DNA region with 180kb length around TM0349 (11.3cM) on Linkage group 1. The causal gene was found by sequencing 26 ORFs located in this region. The mutations in this gene of 4 alleles confirmed this gene was LjSYM102. Predicted amino acid sequence indicated this gene coded a putative membrane-bound ATP-dependent metalloprotease. Less
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