Descripción
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Legumes and bacteria generally known as rhizobia establish an endosymbiotic interaction in a differentiated root structure, the nodule. The symbiosis is responsible for a large fraction of the nitrogen fixed in terrestrial ecosystems. Nitrogen fixation is carried out within organelle-like structures, the symbiosomes, that comprise the rhizobia differentiated into bacteroids and a surrounding plant-derived membrane. At the core of symbiotic nitrogen fixation are a number of highly expressed ferroproteins, such as nitrogenase or leghemoglobin. As a result, iron has to be provided by the host plant in relatively large quantities. Since iron is a growth-limiting nutrient for plants, determining how iron is delivered to the nodule is relevant towards improving legume yields and nitrogen fixation rates. Synchrotron X-ray fluorescence was used to determine where iron was delivered in Medicago truncatula nodules. Our results showed a massive release of iron from the vasculature into the apoplast of the nodule zone II. This is the region of the nodule in which rhizobia are released from the infection thread into host nodular cells, where they will differentiate into nitrogen-fixing symbiosomes. Microarrays were used to characterize the nodule metallotranscriptome as a mean to identify the transporter responsible for iron translocation from the apoplast to the cytosol of the infected cell. Confocal microscopy and GUS-mediated localization of the identified metal importers indicated that MtNramp1 was a likely candidate for this role. This was supported by the reduction of nodulation and of nitrogenase activity of knock-down M. truncatula plants. | |
Internacional
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Si |
Nombre congreso
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Gordon Conference on Cell biology of metal homeostasis |
Tipo de participación
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960 |
Lugar del congreso
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Newport, EE.UU. |
Revisores
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Si |
ISBN o ISSN
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0000000000 |
DOI
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Fecha inicio congreso
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28/07/2013 |
Fecha fin congreso
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02/08/2012 |
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0 |
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Título de las actas
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0 |