Regulation of Symbiotic Nitrogen Fixation in Legume Root Nodules

Schwember, Andrés R.; Schulze, Joachim; Pozo, Alejandro del; Cabeza, Ricardo A.

doi:10.3390/plants8090333

Cited by 73 publications

(56 citation statements)

References 152 publications

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“…The amino acid auxotrophy of bacteroids would be consistent with such control ( Lodwig et al , 2003 ). Finally, as carbon metabolites provided by the plant to the nodule are the primary nutritional source of bacteroids, a control of SNF by sucrose synthase and organic acid allocation has also been suggested ( González et al , 1995 ; Schwember et al , 2019 ). However, the molecular mechanisms involved in these controls remain unknown, and none of these models has yet been validated.…”

Section: Introductionmentioning

confidence: 99%

Responses of mature symbiotic nodules to the whole-plant systemic nitrogen signaling

Lambert

Pervent

Quéré

et al. 2020

Journal of Experimental Botany

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In symbiotic root nodules of legumes, terminally differentiated rhizobia fix atmospheric N2 producing an NH4+ influx that is assimilated by the plant. The plant, in return, provides photosynthates that fuel the symbiotic nitrogen acquisition. Mechanisms responsible for the adjustment of the symbiotic capacity to the plant N demand remain poorly understood. We have investigated the role of systemic signaling of whole-plant N demand on the mature N2-fixing nodules of the model symbiotic association Medicago truncatula/Sinorhizobium using split-root systems. The whole-plant N-satiety signaling rapidly triggers reductions of both N2 fixation and allocation of sugars to the nodule. These responses are associated with the induction of nodule senescence and the activation of plant defenses against microbes, as well as variations in sugars transport and nodule metabolism. The whole-plant N-deficit responses mirror these changes: a rapid increase of sucrose allocation in response to N-deficit is associated with a stimulation of nodule functioning and development resulting in nodule expansion in the long term. Physiological, transcriptomic, and metabolomic data together provide evidence for strong integration of symbiotic nodules into whole-plant nitrogen demand by systemic signaling and suggest roles for sugar allocation and hormones in the signaling mechanisms.

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Section: Introductionmentioning

confidence: 99%

Responses of mature symbiotic nodules to the whole-plant systemic nitrogen signaling

Lambert

Pervent

Quéré

et al. 2020

Journal of Experimental Botany

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“…One of the best-studied symbioses is the symbiotic nitrogen fixation that involves plants (both legumes and non-legumes) and specific diazotrophs (rhizobia and Frankia ). During this symbiotic relationship, a niche and carbon molecules are provided to the microorganisms by the plant in exchange for nitrogen fixation ( Schwember et al, 2019 ). The symbiotic nitrogen fixation is the most efficient fixing system which approximately fixes 170–300 kg of nitrogen per hectare per year.…”

Section: Plant-microbe Interaction Concerning Bnf and Suitable Modifications To Harness The Potential Of Bnfmentioning

confidence: 99%

Diazotrophs for Lowering Nitrogen Pollution Crises: Looking Deep Into the Roots

et al. 2021

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During and after the green revolution in the last century, agrochemicals especially nitrogen (N) were extensively used. However, it resulted in a remarkable increase in crop yield but drastically reduced soil fertility; increased the production cost, food prices, and carbon footprints; and depleted the fossil reserves with huge penalties to the environment and ecological sustainability. The groundwater, rivers, and oceans are loaded with N excess which is an environmental catastrophe. Nitrogen emissions (e.g., ammonia, nitrogen oxide, nitrous oxide) play an important role in global climate change and contribute to particulate matter and acid rain causing respiratory problems, cancers, and damage to forests and buildings. Therefore, the nitrogen-polluted planet Earth needs concerted global efforts to avoid the disaster. Improved agricultural N management focuses on the synchronization of crop N demand and N supply along with improving the N-use efficiency of the crops. However, there is very little focus on the natural sources of N available for plants in the form of diazotrophic bacteria present inside or on the root surface and the rhizosphere. These diazotrophs are the mini-nitrogen factories that convert available (78%) atmospheric N2 to ammonia through a process known as “biological nitrogen fixation” which is then taken up by the plants for its metabolic functioning. Diazotrophs also stimulate root architecture by producing plant hormones and hence improve the plant’s overall ability to uptake nutrients and water. In recent years, nanotechnology has revolutionized the whole agri-industry by introducing nano-fertilizers and coated/slow-releasing fertilizers. With this in mind, we tried to explore the following questions: To what extent can the crop N requirements be met by diazotroph inoculation? Can N input to agriculture be managed in a way leading to environmental benefits and farmers saving money? Can nanotechnology help in technological advancement of diazotroph application? The review suggests that an integrated technology based on slow-releasing nano-fertilizer combined with diazotrophs should be adopted to decrease nitrogen inputs to the agricultural system. This integrated technology would minimize N pollution and N losses to much extent.

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“…N 2 ‐fixation by rhizobia occurs in symbiosis‐specific organs, the nodules, formed in the roots, and occasionally in the stems, of the host plants where the nitrogenase enzyme reduces N 2 to ammonia (NH 4 + ) (Schwember et al . 2019).…”

Section: Introductionmentioning

confidence: 99%

Identification of the endosymbionts from Sulla spinosissima growing in a lead mine tailings in Eastern Morocco as Mesorhizobium camelthorni sv. aridi

Lamin

Alami

Bouhnik

et al. 2020

J. Appl. Microbiol.

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Aims To identify the bacteria nodulating Sulla spinosissima growing profusely in a lead and zinc mine tailings in Eastern Morocco. Methods and Results In all, 32 rhizobial cultures, isolated from root nodules of S. spinosissima growing in soils of the mining site, were tolerant to different heavy metals. The ERIC‐polymerase chain reaction (PCR) fingerprinting analysis clustered the isolates into seven different groups, and the analysis of the 16S rRNA sequences of four selected representative strains, showed they were related to different species of the genus Mesorhizobium. The atpD, glnII and recA housekeeping genes analysis confirmed the affiliation of the four representative strains to Mesorhizobium camelthorni CCNWXJ40‐4T, with similarity percentages varying from 96·30 to 98·30%. The sequences of the nifH gene had 97·33–97·78% similarities with that of M. camelthorni CCNWXJ40‐4T; however, the nodC phylogeny of the four strains diverged from the type and other reference strains of M. camelthorni and formed a separated cluster. The four strains nodulate also Astragalus gombiformis and A. armatus but did not nodulate A. boeticus, Vachellia gummifera, Prosopis chilensis, Cicer arietinum, Lens culinaris, Medicago truncatula, Lupinus luteus or Phaseolus vulgaris. Conclusions Based on similarities of the nodC symbiotic gene and differences in the host range, the strains isolated from S. spinosissima growing in soils of the Sidi Boubker mining site may form a different symbiovar within Mesorhizobium for which the name aridi is proposed. Significance and Impact of the Study In this work, we show that strains of M. camelthorni species nodulating S. spinosissima in the arid area of Eastern Morocco constitute a distinct phylogenetic clade of nodulation genes; we named symbiovar aridi, which encompasses also mesorhizobia from other Mediterranean desert legumes.

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Regulation of Symbiotic Nitrogen Fixation in Legume Root Nodules

Cited by 73 publications

References 152 publications

Responses of mature symbiotic nodules to the whole-plant systemic nitrogen signaling

Responses of mature symbiotic nodules to the whole-plant systemic nitrogen signaling

Diazotrophs for Lowering Nitrogen Pollution Crises: Looking Deep Into the Roots

Identification of the endosymbionts from Sulla spinosissima growing in a lead mine tailings in Eastern Morocco as Mesorhizobium camelthorni sv. aridi

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