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Descripción
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| Symbiotic nitrogen fixation (SNF), performed by diazotrophic bacteria, has an important role in biosphere due to the fact that it transforms N2 from the atmosphere into ammonia, which can be used by the associated legume plants allowing them to grow in soils with low nitrogen content. In this process many metals as iron, are used as cofactors of many proteins of the SNF such as nitrogenase. These metals are delivered by the host plant to the nodule (the organ where symbiosis is established and nitrogen fixation takes place) using a number of metal transporters. In a previous work it was suggested that ferroportins of Medicago truncatula (MtFPN1, MtFPN2 and MtFPN3) might play a role in iron transport connected to SNF, based on their expression patterns. In the present TFG we have performed functional studies in order to prove this hypothesis. First we have used ferroportin knockout mutant plants generated by the insertion of the Tnt1 transposon; however we were not able to obtain homozygous mutant lines, probably because of the many insertions of the transposon that might be affecting seed viability. As an alternative, we used an artificial microRNA-based strategy, in order to silence MtFPN2 showing that it may play a role in premature senescence of the nodule. Ferroportins functionality was also studied by heterologous expression in Saccharomyces cerevisiae, pointing to a role of MtFPN2 (and probably also MtFPN1 and MtFPN3) in iron export. Moreover, we also studied the subcellular localisation of ferroportins of M. truncatula by transient expression in Nicotiana benthamiana leaves. Our results suggest that MtFPN1 is localised in the chloroplast, MtFPN2 in the endoplasmic reticulum and MtFPN3 in the plasma membrane. | |
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Internacional
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ISBN
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Tipo de Tesis
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Otros |
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Calificación
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Sobresaliente |
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Fecha
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01/07/2015 |