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Medicago truncatula Molybdate Transporter type 1 (MtMOT1.3) is a plasma membrane molybdenum transporter required for nitrogenase activity in root nodules under molybdenum deficiency
Author(s) -
TejadaJiménez Manuel,
GilDíez Patricia,
LeónMediavilla Javier,
Wen Jiangqi,
Mysore Kirankumar S.,
Imperial Juan,
GonzálezGuerrero Manuel
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14739
Subject(s) - medicago truncatula , molybdate , nitrogenase , biology , biochemistry , nitrogen fixation , mutant , root nodule , chemistry , symbiosis , gene , genetics , bacteria , organic chemistry
Summary Molybdenum, as a component of the iron‐molybdenum cofactor of nitrogenase, is essential for symbiotic nitrogen fixation. This nutrient has to be provided by the host plant through molybdate transporters. Members of the molybdate transporter family Molybdate Transporter type 1 ( MOT 1) were identified in the model legume Medicago truncatula and their expression in nodules was determined. Yeast toxicity assays, confocal microscopy, and phenotypical characterization of a Transposable Element from Nicotiana tabacum ( Tnt1 ) insertional mutant line were carried out in the one M. truncatula MOT 1 family member specifically expressed in nodules. Among the five MOT 1 members present in the M. truncatula genome, Mt MOT 1.3 is the only one uniquely expressed in nodules. Mt MOT 1.3 shows molybdate transport capabilities when expressed in yeast. Immunolocalization studies revealed that Mt MOT 1.3 is located in the plasma membrane of nodule cells. A mot1.3‐1 knockout mutant showed impaired growth concomitant with a reduction of nitrogenase activity. This phenotype was rescued by increasing molybdate concentrations in the nutritive solution, or upon addition of an assimilable nitrogen source. Furthermore, mot1.3‐1 plants transformed with a functional copy of Mt MOT 1.3 showed a wild‐type‐like phenotype. These data are consistent with a model in which Mt MOT 1.3 is responsible for introducing molybdate into nodule cells, which is later used to synthesize functional nitrogenase.