Carbon And Nitrogen Metabolism In Actinorhizal Nodules

Valverde, Claudio; Huss‐Danell, Kerstin

doi:10.1007/978-1-4020-3547-0_7

Cited by 12 publications

(10 citation statements)

References 94 publications

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“…In the current model, the host plant provides GLU to the bacteroid which is subsequently transaminated to ASP and then transported back to the plant cell and used for ASN synthesis. This process enables the bacteroids to down-regulate NH 4 + assimilation and to provide a fixed-N source to the symbiotic bacteria (Prell & Poole, 2006;White et al, 2007;Valverde & Huss-Danell, 2008). The existence of an AA cycle model was strongly supported by the rapid labeling levels of the AAs in bacteroids and cytosol after incubating pea plants in 15 N 2 (Prell et al, 2009a) in addition to the specificity of the ABC transporter (Bra) which is located in the PBM and has the ability for transporting certain AAs (Hosie et al, 2002;Prell et al, 2009b).…”

Section: S Sulieman and L-s Tranmentioning

confidence: 93%

Asparagine: an amide of particular distinction in the regulation of symbiotic nitrogen fixation of legumes

Sulieman¹,

Tran²

2012

Critical Reviews in Biotechnology

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Section: S Sulieman and L-s Tranmentioning

confidence: 93%

Asparagine: an amide of particular distinction in the regulation of symbiotic nitrogen fixation of legumes

Sulieman¹,

Tran²

2012

Critical Reviews in Biotechnology

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“…Reduced demand for fixed N lowers carbohydrate supply to nodules and reduces associated rates of nodule respiration. This is thought to be mediated by long-distance signals transmitted in phloem from shoots to nodules, which ultimately affect nitrogenase or other key enzymes involved with C or N metabolism of N fixation (Valverde and Huss-Danell 2008). Lower nodule respiration reduces respiratory ATP production and increases pO 2 within vesicles, both of which serve to further reduce nitrogenase activity and N-fixation rates (Silvester et al 2008).…”

Section: Fertilization Effects On N Fixation and Plant N:p Balancementioning

confidence: 99%

“…This likely represents the minimum respiratory cost necessary for maintaining sufficiently low pO 2 to prevent inhibition and inactivation of nitrogenase, coupled with maintenance and growth of nonbacterial nodule tissue. Such a mechanism allows plants to maintain nodule function during periods of reduced N demand, such as at night or during periods of brief C or P stress, without damage to nitrogenase complexes (Valverde and Huss-Danell 2008). In the low range of N fixation, e.g., between 1 and 2 lmol NÁ[g nodule] À1 Áh À1 , plants in þP plots had significantly higher respiration rates (39.1 6 4.5 lmol CO 2 Á[g nodule] À1 Áh À1 ) than plants in either CTL (29.6 6 2.2 lmol CO 2 Á[g nodule] À1 Áh À1 ) or þN plots (26.1 6 1.4 lmol CO 2 Á[g nodule] À1 Áh À1 ), which suggests a higher maintenance cost in nodules up-regulated by P fertilization.…”

Section: Nutritional Effects On Respiratory C Costs Of Nitrogen Fixationmentioning

confidence: 99%

“…Considerable research effort has been directed toward understanding the molecular and biochemical mechanisms for the up-and down-regulation of nodule production and N fixation in leguminous and actinorhizal plants (Wall 2000, Pawlowski and Sprent 2008, Valverde and Huss-Danell 2008, Wall and Berry 2008, Andrews et al 2009, Den Herder and Parniske 2009, Gourion et al 2009), but to our knowledge, no study has determined whether in natural ecosystems, long-lived hosts modify allocation among multiple N-fixing partners in response to changing environmental conditions. Reduced whole-plant N : phosphorus (P) ratios, resulting from decreases in soil N availability and/or increases in soil P availability, are known to increase plant C investment for the up-regulation of nodule production and nitrogenase activity (Uliassi and Ruess 2002, Binkley et al 2003, Gentili and Huss-Danell 2003, Valverde and Wall 2003a.…”

Section: Introductionmentioning

confidence: 99%

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Ecosystem‐level consequences of symbiont partnerships in an N‐fixing shrub from interior Alaskan floodplains

Ruess

Anderson

McFarland

et al. 2013

Ecological Monographs

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In long-lived N-fixing plants, environmental conditions affecting plant growth and N demand vary at multiple temporal and spatial scales, and symbiont assemblages on a given host and patterns of allocation to nodule activities have been shown to vary according to environmental factors, suggesting that hosts may alter partner choice and manipulate symbiont assemblages based on shifting plant needs. This study assessed economic trade-offs among N-fixing symbionts of thin-leaf alder (Alnus tenuifolia) by examining whether alderFrankia associations change in response to the up-regulation (P fertilization) and downregulation (N-fertilization) of N-fixation activities, and whether these changes are associated with differences among Frankia partners in their relative C cost and/or N benefit to A. tenuifolia.Relative to control plots, alder in þP plots had significantly higher nodule biomass and Nfixation rates; these parameters were significantly lower in þN plots, translating to stand-level N inputs that were more than an order of magnitude greater in þP than þN plots. Nodule respiration and N-fixation rates were positively correlated, and analyses revealed that alder employs mechanisms to increase the efficiency of C use when N fixation is up-regulated. Of the eight Frankia OTUs (operational taxonomic units) identified, two were dominant, with significant differences in Frankia OTU composition across samples being explained by fertilization treatment. Dominant OTUs had similar up-and down-regulatory responses to treatments but differed in C costs of N fixation, while the most abundant sub-dominant failed to up-regulate N-fixation rates in þP plots. Differences among Frankia OTUs in traits relevant to plant performance may form the basis for host choice and explain successional shifts in alder-Frankia assemblages. We suggest that manipulation of Frankia assemblages is an adaptation for a species such as A. tenuifolia that maintains a high dependence on atmospheric N across radically different growth environments. Because of the strong effects of thin-leaf alder on soil N contents, it appears that host changes in C partitioning to nodule activities, including the physiological consequences of host specificity for Frankia assemblages, results in alder both driving and responding to environmental heterogeneity at small to large spatial scales.

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“…Understanding the functional partitioning of carbon and nitrogen fluxes in root nodules is of key importance in unravelling the molecular and evolutionary basis of symbiotic adaptation between the partners. This partitioning is very complex, involving subcellular metabolic interactions between the host organelles and the microsymbiont, and higher-order patterns of cell-cell interaction and tissue specialisation, to enable metabolite transport and the sequential steps of metabolite transformation (Schubert 1986;Lodwig et al 2003;Valverde and Huss-Danell 2008).…”

Section: Introductionmentioning

confidence: 99%

New perspectives on nodule nitrogen assimilation in actinorhizal symbioses

Berry

Mendoza-Herrera

Guo

et al. 2011

Functional Plant Biol.

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Nitrogen-fixing root nodules are plant organs specialised for symbiotic transfer of nitrogen and carbon between microsymbiont and host. The organisation of nitrogen assimilation, storage and transport processes is partitioned at the subcellular and tissue levels, in distinctive patterns depending on the symbiotic partners. In this review, recent advances in understanding of actinorhizal nodule nitrogen assimilation are presented. New findings indicate that Frankia within nodules of Datisca glomerata (Presl.) Baill. carries out both primary nitrogen assimilation and biosynthesis of arginine, rather than exporting ammonium. Arginine is a typical storage form of nitrogen in plant tissues, but is a novel nitrogen carrier molecule in root nodule symbioses. Thus Frankia within D. glomerata nodules exhibits considerable metabolic independence. Furthermore, nitrogen reassimilation is likely to take place in the host in the uninfected nodule cortical cells of this root nodule symbiosis, before amino acid export to host sink tissues via the xylem. The role of an augmented pericycle in carbon and nitrogen exchange in root nodules deserves further attention in actinorhizal symbiosis, and further highlights the importance of a comprehensive, structure–function approach to understanding function in root nodules. Moreover, the multiple patterns of compartmentalisation in relation to nitrogen flux within root nodules demonstrate the diversity of possible functional interactions between host and microsymbiont that have evolved in the nitrogen-fixing clade.

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Carbon And Nitrogen Metabolism In Actinorhizal Nodules

Cited by 12 publications

References 94 publications

Asparagine: an amide of particular distinction in the regulation of symbiotic nitrogen fixation of legumes

Asparagine: an amide of particular distinction in the regulation of symbiotic nitrogen fixation of legumes

Ecosystem‐level consequences of symbiont partnerships in an N‐fixing shrub from interior Alaskan floodplains

New perspectives on nodule nitrogen assimilation in actinorhizal symbioses

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