How close are we to nitrogen fixing cereals? Curr Opin Plant Biol

Department of Disease and Stress Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
Current opinion in plant biology (Impact Factor: 7.85). 10/2010; 13(5):556-64. DOI: 10.1016/j.pbi.2010.08.003
Source: PubMed


Engineering nitrogen-fixing cereals is essential for sustainable food production for the projected global population of 9 billion people in 2050. This process will require engineering cereals for nodule organogenesis and infection by nitrogen-fixing bacteria. The symbiosis signalling pathway is essential to establish both bacterial infection and nodule organogenesis in legumes and is also necessary for the establishment of mycorrhizal colonisation. Hence this signalling pathway is also present in cereals and it should be feasible to engineer this signalling pathway for cereal recognition of nitrogen-fixing bacteria. However, establishing a fully function nitrogen-fixing symbiosis in cereals will probably require additional genetic engineering for bacterial colonisation and nodule organogenesis.

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Available from: Myriam Charpentier, Mar 12, 2014
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    • "Legumes have the advantage that, in symbiosis with soil rhizobial bacteria , they can obtain N through biological nitrogen fixation (BNF). However, most agricultural plants, especially grasses, lack this ability and hence there has been sustained interest in transferring the ability to fix nitrogen into grass crops such as corn (Charpentier and Oldroyd, 2010). Plant growth-promoting bacteria (PGPB) colonize roots and engage in associative symbiosis with various host plants, including bioenergy grass species (Santi et al., 2013). "
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    ABSTRACT: Nitrogen-fixing rhizobacteria can promote plant growth; however, it is controversial whether biological nitrogen fixation (BNF) from associative interaction contributes to growth promotion. The roots of Setaria viridis, a model C4 grass, were effectively colonized by bacterial inoculants resulting in a significant enhancement of growth. Nitrogen-13 tracer studies provided direct evidence for tracer uptake by the host plant and incorporation into protein. Indeed, plants showed robust growth under nitrogen limiting conditions when inoculated with an ammonium excreting strain of Azospirillum brasilense. (11) C-labeling experiments showed that patterns in central carbon metabolism and resource allocation exhibited by nitrogen starved plants were largely reversed by bacterial inoculation, such that they resembled plants grown under nitrogen sufficient conditions. Adoption of S. viridis as a model should promote research into the mechanisms of associative nitrogen fixation with the ultimate goal of greater adoption of BNF for sustainable crop production. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Full-text · Article · Jan 2015 · The Plant Journal
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    • "Conversely, under N-sufficiency GlnD deuridylylates PII and GlnK to revert the GlnE-dependent activation of GS (Colnaghi et al., 2001). Symbiotic bacteria normally execute a sophisticated interplay of signals with their partners to assure the specificity of the interaction before starting to cross-feed N-fixation products to their hosts (Charpentier and Oldroyd, 2010). On the other hand, free-living diazotrophs fix sufficient N 2 for their own needs and typically do not excrete significant amounts of N 2 -fixation products into their environment (Colnaghi et al., 1997). "
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    ABSTRACT: The biological nitrogen fixation carried out by some Bacteria and Archaea is one of the most attractive alternatives to synthetic nitrogen fertilizers. In this study we compared the effect of controlling the maximum activation state of the Azotobacter vinelandii glutamine synthase by a point mutation at the active site (D49S mutation) and impairing the ammonium-dependent homeostatic control of nitrogen-fixation genes expression by the ΔnifL mutation on ammonium release by the cells. Strains bearing the single D49S mutation were more efficient ammonium producers under carbon/energy limiting conditions and sustained microalgae growth at the expense of atmospheric N2 in synthetic microalgae-bacteria consortia. Ammonium delivery by the different strains had implications for the microalga's cell-size distribution. It was uncovered an extensive cross regulation between nitrogen fixation and assimilation that extends current knowledge on this key metabolic pathway and might represent valuable hints for further improvements of versatile N2-fixing microbial-cell factories.
    Full-text · Article · May 2014 · Metabolic Engineering
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    • "Uncovering the attributes which shape the ability of plants to host nitrogen - fixing bacteria constitutes a subject of intense study ( Charpentier and Oldroyd , 2010 ; Held et al . , 2010 ; Desbrosses and Stougaard , 2011 ) . "
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    ABSTRACT: A symbiotic mutant of Lotus japonicus, called sunergos1-1 (suner1-1), originated from a har1-1 suppressor screen. suner1-1 supports epidermal infection by Mesorhizobium loti and initiates cell divisions for nodule primordia organogenesis. However, these processes appear to be temporarily stalled early during symbiotic interaction leading to a low nodule number phenotype. This defect is ephemeral and near wild-type nodule numbers are reached by suner1-1 at a later point after infection. Using an approach that combined map-based cloning and next-generation sequencing, we have identified the causative mutation and show that the suner1-1 phenotype is determined by a weak recessive allele, with the corresponding wild-type SUNER1 locus encoding a predicted subunit A of a DNA topoisomerase VI. Our data suggest that at least one function of SUNER1 during symbiosis is to participate in endoreduplication, which is an essential step during normal differentiation of functional, nitrogen-fixing nodules. This article is protected by copyright. All rights reserved.
    Full-text · Article · Mar 2014 · The Plant Journal
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