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Descripción
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| Symbiotic nitrogen fixation (SNF) is carried out by endosymbiotic rhizobia living within nodules developed in legume roots. SNF is responsible for an important part of the atmospheric N2 that is converted to ammonia. As a result of this symbiosis, host plants are able to colonize soils with low nitrogen content. In addition, potentiating SNF is an alternative to the overuse of polluting synthetic nitrogen fertilizers in agriculture. Iron is a critical element for SNF as cofactor of multiple proteins involved in this process (leghemoglobin, nitrogenase,?). Studies in model legume Medicago truncatula have shown that this metal is delivered by the vasculature to the infection/maturation zone (zone II) of the nodule, where it is released to the apoplast (Rodríguez-Haas et al., 2013). From there, the plasma membrane iron transporter MtNramp1 moves it into rhizobia-containing cells (Tejada-jiménez et al., 2016). However, for iron to be able to act as an effective cofactor for SNF, it still has to reach the endosymbiotic rhizobia through the symbiosome membrane that surrounds them. We propose that Ferroportin2 (FPN2) is carries out this role in M. truncatula. Transcriptomic studies show that MtFPN2 is a nodule-specific gene. Yeast complementation assays in a battery of yeast metal transport mutants indicate that MtFPN2 lowers cytosolic Fe2+ content, either by efflux out of the cell, or influx into an organelle. MtFPN2 is located in the nodule vascular bundles and surrounding the endosymbiotic rhizobia, with a distribution that closely resembles the symbiosome membrane. All this data point to a role of MtFPN2 in delivering iron to nitrogen fixing endosymbiotic rhizobia. This is further supported by the phenotypical characterization of a Tnt1-insertion mutant that shows reduced biomass and nitrogenase activity compared to wild type plants, the likely result of a deficiency in essential iron. | |
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Internacional
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No |
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Nombre congreso
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XIII REUNIÓN DE BIOLOGÍA MOLECULAR DE PLANTAS |
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Tipo de participación
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970 |
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Lugar del congreso
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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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22/06/2016 |
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Fecha fin congreso
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24/06/2016 |
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Desde la página
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175 |
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Hasta la página
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175 |
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Título de las actas
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XIII REUNIÓN DE BIOLOGÍA MOLECULAR DE PLANTAS |