Format

Send to

Choose Destination
Plant Physiol. 2015 May;168(1):258-72. doi: 10.1104/pp.114.254672. Epub 2015 Mar 27.

Medicago truncatula natural resistance-associated macrophage Protein1 is required for iron uptake by rhizobia-infected nodule cells.

Author information

1
Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.).
2
Centro de Biotecnología y Genómica de Plantas, Campus de Montegancedo, Universidad Politécnica de Madrid, 28223 Madrid, Spain (M.T.-J., R.C.-R., J.I., M.G.-G.);Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 (I.K., M.U.);Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (M.M.L.); andConsejo Superior de Investigaciones Científicas, 28006 Madrid, Spain (J.I.) manuel.gonzalez@upm.es.

Abstract

Iron is critical for symbiotic nitrogen fixation (SNF) as a key component of multiple ferroproteins involved in this biological process. In the model legume Medicago truncatula, iron is delivered by the vasculature to the infection/maturation zone (zone II) of the nodule, where it is released to the apoplast. From there, plasma membrane iron transporters move it into rhizobia-containing cells, where iron is used as the cofactor of multiple plant and rhizobial proteins (e.g. plant leghemoglobin and bacterial nitrogenase). MtNramp1 (Medtr3g088460) is the M. truncatula Natural Resistance-Associated Macrophage Protein family member, with the highest expression levels in roots and nodules. Immunolocalization studies indicate that MtNramp1 is mainly targeted to the plasma membrane. A loss-of-function nramp1 mutant exhibited reduced growth compared with the wild type under symbiotic conditions, but not when fertilized with mineral nitrogen. Nitrogenase activity was low in the mutant, whereas exogenous iron and expression of wild-type MtNramp1 in mutant nodules increased nitrogen fixation to normal levels. These data are consistent with a model in which MtNramp1 is the main transporter responsible for apoplastic iron uptake by rhizobia-infected cells in zone II.

PMID:
25818701
PMCID:
PMC4424012
DOI:
10.1104/pp.114.254672
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center