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Descripción
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| Legume nodules require relatively large amounts of transition metals (iron, copper, zinc?) as cofactors of some of the key enzymes involved in symbiotic nitrogen fixation (1). These metals are provided by the host plant through the vasculature and, in the case of indeterminate type nodules, released in the infection/differentiation zone of the nodule (2). Consequently, a number of metal transporters must be in place to introduce these elements into the nodule cells to be later delivered to the symbiosomes. We have identified three Medicago truncatula metal transporters encoding genes, MtNramp1 (3), MtZIP6, and MtCOPT1, that are expressed at high levels in the nodule zone where metals have to be incorporated from the apoplast. Yeast complementation assays show that they are respectively involved in iron, zinc, and copper transport towards the cytosol. Consistent with a role in metal uptake from the apoplast, they are located in the plasma membrane of nodule cells. Knock out or knock-down plants of each gene have reduced growth and reduced nitrogenase activity. These phenotypes were restored by reintroducing a wild type form of the mutated gene or by watering the plants with a nutritive solution fortified in the corresponding transported metal. These results are consistent with a model in which MtNramp1 is responsible for Fe2+ loading of nodule cells, while MtZIP6 is for Zn2+ uptake, and MtCOPT1 for Cu+. | |
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Internacional
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Si |
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Nombre congreso
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12th European Nitrogen Fixation Conference |
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Tipo de participación
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960 |
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Lugar del congreso
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Revisores
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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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25/08/2016 |
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Fecha fin congreso
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28/08/2016 |
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Desde la página
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123 |
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Hasta la página
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123 |
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Título de las actas
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12th European Nitrogen Fixation Conference |