RT Journal Article
SR Electronic
T1 <em>Medicago truncatula</em> MOT1.3 is a plasma membrane molybdenum transporter required for nitrogenase activity in root nodules
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 102517
DO 10.1101/102517
A1 Manuel Tejada-Jiménez
A1 Patricia Gil-Díez
A1 Javier León-Mediavilla
A1 Jiangqi Wen
A1 Kirankumar S. Mysore
A1 Juan Imperial
A1 Manuel González-Guerrero
YR 2017
UL http://biorxiv.org/content/early/2017/01/23/102517.abstract
AB Molybdenum has a critical role in biological nitrogen fixation since nitrogenase activity, the central enzyme of this process, requires the presence of this element in its active center. Therefore, any strategy of sustainable agriculture based on biological nitrogen fixation as nitrogen source for crops, requires an efficient molybdenum supply to the nitrogen-fixing tissues. However, in legumes, where symbiotic nitrogen fixation takes place, transporters mediating molybdenum transport have not been identified so far. Here, we report the Medicago truncatula molybdate transporter MtMOT1.3 as responsible for molybdenum supply for symbiotic nitrogen fixation. MtMOT1.3 is a member of the molybdate transporter family MOT1, and the only member of this family in M. truncatula showing a nodule-specific expression. Immunolocalization studies revealed that MtMOT1.3 is expressed in the plasma membrane of nodule cells where nitrogen fixation occurs. A mot1.3 knockout mutant showed an impaired growth concomitant with a reduction in nitrogenase activity. This phenotype was rescued upon addition of an assimilable nitrogen source or, under nitrogen-limiting conditions, by increasing molybdate concentrations in the nutritive solution. Furthermore, mot1.3 mutant plants transformed with a functional copy of MtMOT1.3 showed a wild type-like phenotype. These results are important to understand how legumes supply molybdenum for symbiotic nitrogen fixation