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Descripción
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| Iron plays an essential role in symbiotic nitrogen fixation (SNF), as the key cofactor of many of the proteins mediating this process. SNF is mostly carried out in differentiated legume root structures, the nodules, where endosymbiotic bacteria (rhizobia) convert N2 into NH3 that is transferred to the plant. The iron cofactor is provided by the host plant through the vasculature and released in the apoplast of the infection/differentiation zone of the nodule, the region where rhizobia differentiate and synthesize many of the ferroproteins required for SNF. From there, metal transporters must mediate iron uptake from the apoplast into the cytosol of the infected nodule cells. Our results indicate that MtNramp1, a Medicago truncatula member of the Nramp family of metal transporters, enables this transport. MtNramp1 is upregulated by nodulation with an expression maximum in the infection/differentiation zone of the nodule. Reporter gene and immunolocalization data indicate that it is localized in the plasma membrane of cells in the root endodermis and in the infection/differentiation zone of the nodule. There, it introduces iron into the cytosol. Functional analyses in null mutant nramp1-1 showed that MtNramp1 plays a critical role in SNF. Under symbiotic conditions, nramp1-1 plants had reduced growth, a smaller nodule size, and diminshed iron-dependent nitrogenase activity when compared to the wild type plants. All these phenotypes reverted when nramp1-1 was transformed with a plasmid expressing MtNramp1 or watered with a nutritive solution fortified in iron. These results are consistent with a model in which MtNramp1 is responsible for iron loading of rhizobia infected cells in the nodule. | |
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Internacional
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Si |
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Nombre congreso
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XIV Congreso Hispano-Luso de Fisiología Vegetal. XXI Reunión de la Sociedad Española de Fisiología Vegetal |
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Tipo de participación
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960 |
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Lugar del congreso
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Toledo |
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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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14/06/2015 |
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Fecha fin congreso
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17/06/2015 |
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Desde la página
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75 |
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Hasta la página
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75 |
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Título de las actas
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XIV Congreso Hispano-Luso de Fisiología Vegetal. XXI Reunión de la Sociedad Española de Fisiología Vegetal |