Nitrogen Assimilation in the Legume-Rhizobium Symbiosis: A Joint Endeavour

Miflin, B. J.; Cullimore, Julie V.

doi:10.1007/978-3-7091-8739-5_5

Cited by 21 publications

(11 citation statements)

References 183 publications

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“…excreted into the plant cell cytosol and assimilated by the plant GS [6,29,32]. The activity of plant nodule GS has been shown to increase severalfold during nodulation of many legumes [6,29,32], and in Phaseolus vulgaris this increase is largely due to the induction of a specific GS gene [ 10,16] which leads to the production of a specific cytosolic GS polypeptide (7) [22] and isoenzyme [21].…”

Section: Introductionmentioning

confidence: 99%

“…The activity of plant nodule GS has been shown to increase severalfold during nodulation of many legumes [6,29,32], and in Phaseolus vulgaris this increase is largely due to the induction of a specific GS gene [ 10,16] which leads to the production of a specific cytosolic GS polypeptide (7) [22] and isoenzyme [21]. This induction appears to occur before the onset of dinitrogen fixation [31 ].…”

Section: Introductionmentioning

confidence: 99%

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cDNA sequence and differential expression of the gene encoding the glutamine synthetase ? polypeptide ofPhaseolus vulgaris L.

1989

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We report the sequence of an essentially full-length glutamine synthetase (GS) cDNA clone (pcGS-γ1) isolated from a root nodule library ofPhaseolus vulgaris L. The polypeptide encoded by this cDNA has been producedin vitro by transcription/translation and shown to co-migrate on two-dimensional gels with the previously identified major cytosolic GS polypeptide (γ) of nodules. Two previously identified GS cDNA clones, pR-2 and pR-1 (see Gebhardtet al., EMBO J 5: 1429-1435, 1986) have similarly been shown to encode the α and β cytosolic GS polypeptides respectively. An RNase protection technique has been used to analyse specifically and quantitatively the abundance of mRNA related to these three GS cDNAs and to the cDNA (pcGS-δ1) encoding the chloroplast-located GS, during nodulation. Differences in the abundances of these mRNAs at different times suggest that they are not coordinately regulated. Moreover, using this technique mRNA specifically related to pcGS-γ1 was found at high levels in nodules but not in roots or leaves. Surprisingly the expression of this gene is not nodule-specific as previously suggested, as its mRNA was also detected, but at lower levels, in stems, petioles and in green cotyledons. By comparison, mRNA related to a leghaemoglobin gene was detected only in nodules. Comparisons of the relative abundances of the pcGS-γ1 mRNA and the γ polypeptide in different organs and at different stages during nodulation, suggest that the appearance of the γ polypeptide is largely under transcriptional control.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

cDNA sequence and differential expression of the gene encoding the glutamine synthetase ? polypeptide ofPhaseolus vulgaris L.

1989

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“…GSI is a homolog of the ginA gene product of enteric bacteria in terms of its heat stability, molecular mass (monomer -55,000 daltons), subunit struc-ture (12 subunits), and adenylylation properties. GSII, on the other hand, is composed of eight identical subunits of -36,000 daltons each, heat labile, and not subject to adenylylation control (14,28,40,47). In fact, GSII is structurally similar to GS forms found in eucaryotic organisms, such as plants (9).…”

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confidence: 99%

Rhizobium meliloti 1021 has three differentially regulated loci involved in glutamine biosynthesis, none of which is essential for symbiotic nitrogen fixation

Bruijn¹,

Rossbach²,

Schneider³

et al. 1989

J Bacteriol

103

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“…The assimilation of ammonia produced in nodules occurs via the combined functions of GS and GOGAT in the host-cell cytoplasm (Miflin and Cullimore, 1984). Probably as a consequence of higher nitrogenase activity and higher availability of carbohydrate, GS transferase and GOGAT activities were also higher in stem than in root nodules of both species (Table 4).…”

Section: Resultsmentioning

confidence: 98%

Physiological comparisons of root and stem nodules of Aeschynomene scabra and Sesbania rostrata

1992

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A few legume species possess the ability to form N2-fixing nodules on stems as well as on roots. Little is known of the functional characteristics of stem nodules, or to what extent they differ from root nodules.Stem and root nodules of greenhouse-grown plants of Aeschynomene scabra (inoculated with the photosynthetic rhizobial strain B T A i l ) and Sesbania rostrata (inoculated with Azorhizobium caulinodans strain BTSr 3) were examined for assimilation of 14CO2 in the light and dark, soluble carbohydrate and starch contents, acetylene reduction activity, relative efficiency of nitrogenase in terms of uptake-hydrogenase activity, glutamine synthetase and glutamate synthase, and reduced N and ureide contents. In general, stem nodules possessed higher enzyme activities and metabolite contents than did root nodules, suggesting that they fix N 2 with greater energy efficiency. This greater efficiency correlated with photosynthesis in the cortex of stem nodules. Differences in enzyme activities and metabolite contents between the stem nodules on A. scabra and those on S. rostrata probably result either from legume-species characteristics or from the photosynthetic capability of strain BTAi 1.

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Nitrogen Assimilation in the Legume-Rhizobium Symbiosis: A Joint Endeavour

Cited by 21 publications

References 183 publications

cDNA sequence and differential expression of the gene encoding the glutamine synthetase ? polypeptide ofPhaseolus vulgaris L.

cDNA sequence and differential expression of the gene encoding the glutamine synthetase ? polypeptide ofPhaseolus vulgaris L.

Rhizobium meliloti 1021 has three differentially regulated loci involved in glutamine biosynthesis, none of which is essential for symbiotic nitrogen fixation

Physiological comparisons of root and stem nodules of Aeschynomene scabra and Sesbania rostrata

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