Amino-acid cycling drives nitrogen fixation in the legume–Rhizobium symbiosis

Lodwig, E. M.; Hosie, Arthur H.F.; Bourdes, Alex; Findlay, Kim; Allaway, David; Karunakaran, Ramakrishnan; Downie, J. Allan; Poole, Philip S.

doi:10.1038/nature01527

Cited by 413 publications

(343 citation statements)

References 22 publications

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“…Possibly, the reduced ammonium availability, could affect the nitrogen-fixation activity observed in the nodules of antisense plants (Fig. 5b), by altering the rate of aminoacids synthesis and cycling that was proposed to drive N 2 fixation (Lodwig et al 2003). …”

Section: Discussionmentioning

confidence: 99%

Tissue-specific down-regulation of LjAMT1;1 compromises nodule function and enhances nodulation in Lotus japonicus

et al. 2008

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Plant ammonium transporters of the AMT1 family are involved in N-uptake from the soil and ammonium transport, and recycling within the plant. Although AMT1 genes are known to be expressed in nitrogen-fixing nodules of legumes, their precise roles in this specialized organ remain unknown. We have taken a reverse-genetic approach to decipher the physiological role of LjAMT1;1 in Lotus japonicus nodules. LjAMT1;1 is normally expressed in both the infected zone and the vascular tissue of Lotus nodules. Inhibition of LjAMT1;1 gene expression, using an antisense gene construct driven by a leghemoglobin promoter resulted in a substantial reduction of LjAMT1;1 transcript in the infected tissue but not the vascular bundles of transgenic plants. As a result, the nitrogen-fixing activity of nodules was partially impaired and nodule number increased compared to control plants. Expression of LjAMT1;1-GFP fusion protein in plant cells indicated a plasma-membrane location for the LjAMT1;1 protein.Taken together, the results are consistent with a role of LjAMT1;1 in retaining ammonium derived from symbiotic nitrogen fixation in plant cells prior to its assimilation.

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Section: Discussionmentioning

confidence: 99%

Tissue-specific down-regulation of LjAMT1;1 compromises nodule function and enhances nodulation in Lotus japonicus

et al. 2008

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“…Effective symbiotic interaction is supported by a complex network of nutrient exchange between the two partners, plant and Rhizobium, and is controlled by a well-regulated carbon/nitrogen balance (Lodwig et al 2003;Libault 2014). Indeed, photosynthate and other plant nutrients are transported to nodules to reduce optimally atmospheric N 2 (Lodwig et al 2003;Libault 2014).…”

Section: Introductionmentioning

confidence: 99%

Nitrate transporters: an overview in legumes

Pellizzaro

Alibert

Planchet

et al. 2017

Planta

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Main conclusion The nitrate transporters, belonging to NPF and NRT2 families, play critical roles in nitrate signaling, root growth and nodule development in legumes.Nitrate plays an essential role during plant development as nutrient and also as signal molecule, in both cases working via the activity of nitrate transporters. To date, few studies on NRT2 or NPF nitrate transporters in legumes have been reported, and most of those concern Lotus japonicus and Medicago truncatula. A molecular characterization led to the identification of 4 putative LjNRT2 and 37 putative LjNPF gene sequences in L. japonicus. In M. truncatula, the NRT2 family is composed of 3 putative members. Using the new genome annotation of M. truncatula (Mt4.0), we identified, for this review, 97 putative MtNPF sequences, including 32 new sequences relative to previous studies. Functional characterization has been published for only two MtNPF genes, encoding nitrate transporters of M. truncatula. Both transporters have a role in root system development via abscisic acid signaling: MtNPF6.8 acts as a nitrate sensor during the cell elongation of the primary root, while MtNPF1.7 contributes to the cellular organization of the root tip and nodule formation. An in silico expression study of MtNPF genes confirmed that NPF genes are expressed in nodules, as previously shown for L. japonicus, suggesting a role for the corresponding proteins in nitrate transport, or signal perception in nodules. This review summarizes our knowledge of legume nitrate transporters and discusses new roles for these proteins based on recent discoveries.

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“…The occurrence of low N 2 -fixing and ineffective rhizobia cheating strains in the same plant is common (Singleton and Tavares, 1986;Bronstein, 2001), and accumulation of resources by some non-fixing rhizobia in bacteroid stage has been proposed as cheating advantage at plant´s expenses (Denison, 2000). However, this accumulation is a general metabolic consequence of reduced carbon demand from the plant (Lodwig, 2003) and not necessarily implies rhizobia further survival advantages (Streeter et al, 1995).…”

Section: Introductionmentioning

confidence: 99%