Carbon and nitrogen metabolism in legume root nodules

Rawsthorne, Stephen; Minchin, F. R.; Summerfield, R. J.; Cookson, Claire; Coombs, J.

doi:10.1016/0031-9422(80)83181-5

Cited by 162 publications

(80 citation statements)

References 123 publications

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“…A concomitant decrease in the Glc content of the nodules is consistent with a more active utilization of C skeletons exported from the shoots and further channeled through the oxaloacetate-Asp pathway (Rawstone et al, 1980). The relatively modest increase in free ammonium in nodules of the transformed plants in comparison with the decrease in GS activity and the fact that biological N 2 fixation releasing a constant flux of ammonium was not affected also support this hypothesis.…”

Section: Discussionsupporting

confidence: 56%

Does Lowering Glutamine Synthetase Activity in Nodules Modify Nitrogen Metabolism and Growth of Lotus japonicus?

et al. 2003

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A cDNA encoding cytosolic glutamine synthetase (GS) from Lotus japonicus was fused in the antisense orientation relative to the nodule-specific LBC3 promoter of soybean (Glycine max) and introduced into L. japonicus via transformation with Agrobacterium tumefaciens. Among the 12 independent transformed lines into which the construct was introduced, some of them showed diminished levels of GS1 mRNA and lower levels of GS activity. Three of these lines were selected and their T 1 progeny was further analyzed both for plant biomass production and carbon and nitrogen (N) metabolites content under symbiotic N-fixing conditions. Analysis of these plants revealed an increase in fresh weight in nodules, roots and shoots. The reduction in GS activity was found to correlate with an increase in amino acid content of the nodules, which was primarily due to an increase in asparagine content. Thus, this study supports the hypothesis that when GS becomes limiting, other enzymes (e.g. asparagine synthetase) that have the capacity to assimilate ammonium may be important in controlling the flux of reduced N in temperate legumes such as L. japonicus. Whether these alternative metabolic pathways are important in the control of plant biomass production still remains to be fully elucidated.Nitrogen (N) is one of the major limiting factors for plant growth. However, an excessive external supply of N causes major problems in agriculture and the environment, mostly due to nitrate leaching into underground water (Benes et al., 1989), not only polluting the aquatic environment but also resulting in a high nitrate content in food and drinks (Moller et al., 1990). Paradoxically, dinitrogen is 80% of the atmosphere, but it can only be assimilated by prokaryotic symbiotic or free-living diazotrophic organisms possessing nitrogenase activity (Dilworth, 1974). In higher plants, nitrate and ammonium are the two major inorganic N compounds that can be directly assimilated (Beevers, 1976). They are provided either artificially by the external supply of fertilizers, bacterial nitrification, or atmospheric reduction of dinitrogen during lightning, or naturally through biological N fixation. Therefore, regulation of inorganic N assimilation and incorporation of inorganic N into organic matter is of major importance not only in maintaining a sustainable agriculture but also protecting the environment.Over the past few years, attention has been particularly focused on the enzyme Gln synthetase (GS; E.C. 6.3.1.2) because of its central role in N metabolism and its diverse metabolic and developmental regulation in different plant species and organs (Cren and Hirel, 1999). Two major isoforms exist for the GS enzyme: cytosolic GS, occurring in the cytoplasm of leaves and non photosynthetic organs, and chloroplastic GS, present only in the chloroplasts of photosynthetic tissues and the plastids of roots or etiolated plants. The relative proportions of the cytosolic and plastidial GS activity may vary within different organs of the same plant or within dif...

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Section: Discussionsupporting

confidence: 56%

Does Lowering Glutamine Synthetase Activity in Nodules Modify Nitrogen Metabolism and Growth of Lotus japonicus?

et al. 2003

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“…Duing the period of developing nitrogenase activity, the specfic activity of fumuase, hydroxybutyrate dehydrogenase, ,-ketothiohlse, and pyruvate dehydrogenase complex incesed whereas acetoacetate-succinyl-CoA transferase and isocitrate dehydrogenase decreased (2,8,9,15,17,21,25,28,29).The carbon metabolism of developing and senescing nodules and the metabolism of bacteroids have been reviewed recently (5,19,27 PHB has been measured in many rhizobia species (7,12,14 The purpose of this investigation was, first, to establish that PDC, selected enzymes from the citric acid cycle, (IDH, MDH, and FMR) and of the PHB cycle (KT, HBD, and AST) were present during the period of nitrogen fixation and PHB accumulation in R. japonicum; second, to follow their activity as a function ofage; and third, to relate temporal changes in activities to those of nitrogenase and PHB accumulation through the use of dispersion diagrams. …”

mentioning

confidence: 99%

Enzymes of the Poly-β-Hydroxybutyrate and Citric Acid Cycles of Rhizobium japonicum Bacteroids

Karr

Waters²,

Suzuki³

et al. 1984

Plant Physiol.

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ABSTRACrThe activities of several enzymes of the citric acid and poly-4e-hydroxybutyrate cycles were measured in Rhizobiumjapeoicwm 3IIB-143 bacteroids which had been isolated from soybean nodules by sucrose gradient centrifupaton. Duing the period of developing nitrogenase activity, the specfic activity of fumuase, hydroxybutyrate dehydrogenase, ,-ketothiohlse, and pyruvate dehydrogenase complex incesed whereas acetoacetate-succinyl-CoA transferase and isocitrate dehydrogenase decreased (2,8,9,15,17,21,25,28,29).The carbon metabolism of developing and senescing nodules and the metabolism of bacteroids have been reviewed recently (5,19,27 PHB has been measured in many rhizobia species (7,12,14 The purpose of this investigation was, first, to establish that PDC, selected enzymes from the citric acid cycle, (IDH, MDH, and FMR) and of the PHB cycle (KT, HBD, and AST) were present during the period of nitrogen fixation and PHB accumulation in R. japonicum; second, to follow their activity as a function ofage; and third, to relate temporal changes in activities to those of nitrogenase and PHB accumulation through the use of dispersion diagrams.

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“…2 ) The most effective substrates for stimulation of respiration and dinitrogen fixation (acetylene reduction) of isolated bacteroid suspensions were organic acids, especially succinate and malate. 3 ) Though pathways for conversion of sucrose to organic acids in nodule tissues have yet to be fully, understood, Kouchi and Yoneyama 4 ) extensively investigated 13C incorporation into various plant tissue constituents after the plants had assimilated 13C02 for 8 hr in a steady state, and showed rapid turnover and labeling of Abbreviations: ARA, acetylene reduction activity; DTT, dithiothreitol; ex-KG, ex-ketoglutarate. succinate in soybean nodules.…”

mentioning

confidence: 99%

Effects of Oxygen Concentration and Leghemoglobin on Organic Acid Degradation by Isolated Soybean Nodule Bacteriods

Tajima

Sasahara²,

Kouchi

et al. 1985

Agricultural and Biological Chemistry

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Carbon and nitrogen metabolism in legume root nodules

Cited by 162 publications

References 123 publications

Does Lowering Glutamine Synthetase Activity in Nodules Modify Nitrogen Metabolism and Growth of Lotus japonicus?

Does Lowering Glutamine Synthetase Activity in Nodules Modify Nitrogen Metabolism and Growth of Lotus japonicus?

Enzymes of the Poly-β-Hydroxybutyrate and Citric Acid Cycles of Rhizobium japonicum Bacteroids

Effects of Oxygen Concentration and Leghemoglobin on Organic Acid Degradation by Isolated Soybean Nodule Bacteriods

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