Control of NO level in rhizobium-legume root nodules

Meilhoc, Eliane; Blanquet, Pauline; Cam, Yvan; Bruand, Claude

doi:10.4161/psb.25923

Cited by 23 publications

(20 citation statements)

References 28 publications

(34 reference statements)

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“…These proteins might not have the same role and/or not function in the same conditions inside nodules. Indeed they have different localization in the bacterial cell, and on the other hand, they display a different expression pattern within the different zones of the nodules (Meilhoc et al, 2013;Roux et al, 2014). Although the involvement of Hmp, Nor, NnrS 1 and NnrS 2 in NO detoxification has been demonstrated, the potential impact of those NO-consuming proteins on the emission of the GHG N 2 O by alfalfa nodules is poorly investigated.…”

Section: No In M Truncatula Nodulesmentioning

confidence: 97%

“…In this context, plant haemoglobins (nonsymbiotic haemoglobins but also leghaemoglobins or truncated haemoglobins) have been shown to be involved in NO degradation (Gupta et al, 2011). From the bacterial side, two E. meliloti proteins, Hmp and Nor are the major NO-detoxifying enzymes essential in maintaining a balanced NO concentration and an efficient symbiosis (Cam et al, 2012;Meilhoc, Blanquet, Cam, & Bruand, 2013;Fig. 11).…”

Section: No In M Truncatula Nodulesmentioning

confidence: 99%

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Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria

Torres

Simon

Rowley

et al. 2016

Advances in Microbial Physiology

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Nitrous oxide (N2O) is an important greenhouse gas (GHG) with substantial global warming potential and also contributes to ozone depletion through photochemical nitric oxide (NO) production in the stratosphere. The negative effects of N2O on climate and stratospheric ozone make N2O mitigation an international challenge. More than 60% of global N2O emissions are emitted from agricultural soils mainly due to the application of synthetic nitrogen-containing fertilizers. Thus, mitigation strategies must be developed which increase (or at least do not negatively impact) on agricultural efficiency whilst decrease the levels of N2O released. This aim is particularly important in the context of the ever expanding population and subsequent increased burden on the food chain. More than two-thirds of N2O emissions from soils can be attributed to bacterial and fungal denitrification and nitrification processes. In ammonia-oxidizing bacteria, N2O is formed through the oxidation of hydroxylamine to nitrite. In denitrifiers, nitrate is reduced to N2 via nitrite, NO and N2O production. In addition to denitrification, respiratory nitrate ammonification (also termed dissimilatory nitrate reduction to ammonium) is another important nitrate-reducing mechanism in soil, responsible for the loss of nitrate and production of N2O from reduction of NO that is formed as a by-product of the reduction process. This review will synthesize our current understanding of the environmental, regulatory and biochemical control of N2O emissions by nitrate-reducing bacteria and point to new solutions for agricultural GHG mitigation.

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Section: No In M Truncatula Nodulesmentioning

confidence: 97%

Section: No In M Truncatula Nodulesmentioning

confidence: 99%

Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria

Torres

Simon

Rowley

et al. 2016

Advances in Microbial Physiology

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“…Using a biosensor S. meliloti strain, authors suggested that NO levels were the highest in the most proximal zone of the nodule, consistent with the hypothesis that NO could play a signalling function at the onset of senescence. Interestingly, an increase of NO levels in M. truncatula nodules, resulting either from the use of S. meliloti strains deficient in NO degradation ( hmp , norB , and nnrS1 ) or from the exogenous addition of a NO donor, led to a premature senescence of the nodules, the severity of which correlated with the NO levels inside the nodules (Blanquet et al, ; Cam et al ., ; Meilhoc, Blanquet, Cam, & Bruand, ). In contrast, overexpression of the hmp gene led to a decrease in NO levels and a delay in nodule senescence, whether developmental or dark‐induced (Cam et al, ).…”

Section: Signalling Role Of No and The Interplay Between Ros No Andmentioning

confidence: 99%

Pathways of nitric oxide metabolism and operation of phytoglobins in legume nodules: Missing links and future directions

et al. 2018

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The interaction between legumes and rhizobia leads to the establishment of a beneficial symbiotic relationship. Recent advances in legume - rhizobium symbiosis revealed that various reactive oxygen and nitrogen species including nitric oxide (NO) play important roles during this process. Nodule development occurs with a transition from a normoxic environment during the establishment of symbiosis to a microoxic environment in functional nodules. Such oxygen dynamics are required for activation and repression of various NO production and scavenging pathways. Both the plant and bacterial partners participate in the synthesis and degradation of NO. However, the pathways of NO production and degradation as well as their cross-talk and involvement in the metabolism are still a matter of debate. The plant-originated reductive pathways are known to contribute to the NO production in nodules under hypoxic conditions. Non-symbiotic hemoglobin (phytoglobin) (Pgb) possesses high NO oxygenation capacity, buffers and scavenges NO. Its operation, through a respiratory cycle called Pgb-NO cycle, leads to the maintenance of redox and energy balance in nodules. The role of Pgb/NO cycle under fluctuating NO production from soil needs further investigation for complete understanding of NO regulatory mechanism governing nodule development to attain optimal food security under changing environment.

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“…Similarly, NO level was increased in nodules of common bean exposed to nitrate, when elicited by a R. etli norC mutant as compared to the WT (Gomez-Hernandez et al, 2011). Interestingly, in S. meliloti , NO was found to induce nor expression (Meilhoc et al, 2010), and a nor mutant strain is more sensitive than a WT strain to a NO donor, and triggers early senescence of M. truncatula nodules (Meilhoc et al, 2013). It is important to note that Hmp does not compensate for the absence of Nor, and vice versa .…”

Section: Role Of Hemoproteins In the Control Of No Levelmentioning

confidence: 99%

Which role for nitric oxide in symbiotic N2-fixing nodules: toxic by-product or useful signaling/metabolic intermediate?

Boscari¹,

Meilhoc²,

Castella³

et al. 2013

Front. Plant Sci.

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The interaction between legumes and rhizobia leads to the establishment of a symbiotic relationship characterized by the formation of new organs called nodules, in which bacteria have the ability to fix atmospheric nitrogen (N2) via the nitrogenase activity. Significant nitric oxide (NO) production was evidenced in the N2-fixing nodules suggesting that it may impact the symbiotic process. Indeed, NO was shown to be a potent inhibitor of nitrogenase activity and symbiotic N2 fixation. It has also been shown that NO production is increased in hypoxic nodules and this production was supposed to be linked – via a nitrate/NO respiration process – with improved capacity of the nodules to maintain their energy status under hypoxic conditions. Other data suggest that NO might be a developmental signal involved in the induction of nodule senescence. Hence, the questions were raised of the toxic effects versus signaling/metabolic functions of NO, and of the regulation of NO levels compatible with nitrogenase activity. The present review analyses the different roles of NO in functioning nodules, and discusses the role of plant and bacterial (flavo)hemoglobins in the control of NO level in nodules.

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Control of NO level in rhizobium-legume root nodules

Cited by 23 publications

References 28 publications

Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria

Nitrous Oxide Metabolism in Nitrate-Reducing Bacteria

Pathways of nitric oxide metabolism and operation of phytoglobins in legume nodules: Missing links and future directions

Which role for nitric oxide in symbiotic N2-fixing nodules: toxic by-product or useful signaling/metabolic intermediate?

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