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Descripción
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| Functioning of the Rhizobium-legume symbiosis requires the metabolic adjustment of both partners to generate nitrogen-fixing root nodules. The ability of some Rhizobium species to associate with several legumes provides a good system to study such adaptations using a common bacterial background with different hosts. Some host-specific differences, such as the induction of hydrogen-recycling hydrogenase, have been described previously (1), although the molecular basis for these differences had not been established. Our research work aims at the elucidation of mechanisms involved in the adaptation of rhizobia to specific legume hosts, taking into account factors originated from both symbionts. The working hypothesis is that different legume plants provide different environments to the bacteria within the nodule, thus inducing host-specific responses. In the case of IRLC group of legumes, which includes Medicago, Pisum, Lens, Vicia, and other genera, the plant symbiont exports to the symbiosome a set of multiple peptides, structurally similar to antimicrobial peptides of the defensin type and designated as NCR (Nodule-specific Cystein-Rich peptides, (2)). It is assumed that such peptides control multiple aspects of the bacterial physiology, thus converting it into a ?metabolic slave? dedicated to fix nitrogen. We have carried out a comparative proteomic analysis of extracts from bacteroids induced by Rhizobium leguminosarum bv. viciae UPM791 in pea and lentil plants. The analysis revealed the existence of a significant number of proteins displaying different levels of expression in a host-specific manner. Proteins identified include several stress-response proteins, a GntR-type transcriptional regulator, and an aminotransferase that could be relevant for the C/N metabolism of the bacteroid. Also, extracts from pea and lentil bacteroids contained significantly different sets of NCR peptides. We hypothesize that the different cocktail of NCR peptides provided by each legume plant might be partly responsible for the different protein profile of the bacteroids. Mutants specifically altered in the potential host-adaptation bacterial genes identified in this work are being generated, and their symbiotic phenotype will be presented and discussed at the conference. (1) Brito et al. (2008) Mol. Plant Microbe Interact. 21: 597-604 (2) Kondorosi et al. (2013) Annu. Rev. Microbiol 67: 611-628. Funds supporting this work were provided by Project SYMBIOSIGNAL (MINECO BIO2013-43040-P). | |
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Internacional
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Si |
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Nombre congreso
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20th. International Congress on Nitrogen Fixation |
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Tipo de participación
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960 |
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Lugar del congreso
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Granada, Spain |
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Revisores
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Si |
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ISBN o ISSN
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0000000000 |
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DOI
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Fecha inicio congreso
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03/09/2017 |
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Fecha fin congreso
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07/09/2017 |
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Desde la página
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200 |
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Hasta la página
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200 |
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Título de las actas
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Proceeding of the 20th. International Congress on Nitrogen Fixation |