Induction of glutamate synthase during nodule development in lupin

Robertson, John; Warburton, Marion P.; Farnden, Kevin J. F.

doi:10.1016/0014-5793(75)80950-1

Cited by 98 publications

(32 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The study indicated that the proportion of nitrogen as ureide in sap was a relatively stable quantity, Most recent evidence suggests that the amide group ofglutamine is the initial product of ammonia assimilation after N2 fixation or NO3 reduction (12) and that this nitrogen serves directly in the synthesis of glutamate (18), and in the synthesis of the amide group of asparagine by a transamidation reaction with aspartate (19). Ureide formation based on purine biosynthesis requires two atoms of amide nitrogen, either as glutamine or asparagine (7,17), and a N atom of aspartate to form three of the four N atoms of allantoin and allantoic acid (4), so synthesis of these compounds could be envisaged as competitive with asparagine formation.…”

Section: Methodsmentioning

confidence: 99%

Nitrogen Nutrition and Xylem Transport of Nitrogen in Ureide-producing Grain Legumes

Pate¹,

Atkins²,

White³

et al. 1980

Plant Physiol.

150

View full text Add to dashboard Cite

Xylem sap composition was examined in nodulated and nonnodulated cowpea ( Vigna unguicd L.I Walp.) plants receiving a range of levels of NO3 and in eight other ureide-forming legumes udlizing NO3 or N2 as sole source of nitrogen. A 15N dilution technique determined the proportions of plant nitrogen derived from N2 in the nodulated cowpeas fed NO. Xylem sap composition of N03-fed, nodulated cowpea varied predictably with the relative extents to which N2 and NO3 were being utilized. The ratios of asparagine to glutamine (N/N) and of NO3 to ureide (N/N) in xylem sap increased with increasing dependence on NO3 whereas per cent of xylem nitrogen as ureide and the ratio of ureide plus glutamine to asparagine plus NO3 (N/N) in xylem sap increased with increasing dependence on N2 fixation. The amounts of NO3 and ureides stored in leaflets, stems plus petioles, and roots of cowpea varied in a complex manner with level of NO3 and the presence or absence of N2 fixation. All species showed higher proportions of organic nitrogen as ureide and several-fold lower ratios of asparagine to glutamine in their xylem sap when relying on N2 than when utilizing NO3. In nodulated (minus nitrate) cowpea and mung bean (Vigna radiata [L.1 Wilczek) the percentage of xylem nitrogen as ureide remained constant during growth but the ratio of asparagine to glutamine varied considerably. The biochemical significance of the above differences in xylem sap compositdon was discussed.A number of legumes, especially tropical species, synthesize allantoin and allantoic acid from currently fixed N2 in nodules and use these compounds for transport and storage of N (1, 3, 6, 10). In soybean (Glycine max [L.] Merr.) the ureides are more prominent in nodulated plants than in plants grown with NO3 or NH4 salts (8, 11), suggesting a special association between N2 fixation and ureide formation (9), and the possibility of using ureide levels in plant tissues or transport fluids to determine the extent to which a field-grown crop is relying on symbiosis as opposed to combined forms of N from soil or fertilizer. This paper describes xylem sap composition of N2 and N03-fed cowpea (Vigna unguiculata [L.] Walp.) and of other grain legumes which form ureides, and suggests how compositional features of the sap might be used to evaluate the N2-fixing status of nodulated plants grown in the presence of NO3. MATERIALS AND METHODSThe species studied were cowpea (V. unguiculata [L.] Plants were grown in pots of heat sterilized sand during summer in a naturally lit glasshouse maintained within the temperature range 20-35 C by supplementary heating (night) and evaporative cooling (day). One set of plants of each species was inoculated with an effective Rhizobium (strain CB437, for soybean, strain NGR234 for horse gram, and strain CB756 for all other species) and grown with a N-free culture solution. A matching set of uninoculated plants received culture solution containing 10 mM NO3. By using this level of NO3, sterile sand and effective surface sterilization of s...

show abstract

Section: Methodsmentioning

confidence: 99%

Nitrogen Nutrition and Xylem Transport of Nitrogen in Ureide-producing Grain Legumes

Pate¹,

Atkins²,

White³

et al. 1980

Plant Physiol.

150

View full text Add to dashboard Cite

show abstract

“…It is now well accepted that glutamate synthase (glutamine:aketoglutarate aminotransferase; GOGAT2) catalyzes the second step of nitrogen assimilation into glutamate via glutamine in the presence of glutamine synthetase (EC 6.3.1.2) in bacteria (18,32), algae (10,14), nitrogen-fixing organisms (3,24), and higher plants (16).…”

mentioning

confidence: 99%

Glutamate Synthase Isoforms in Rice

Suzuki¹,

Vidal²,

Gadal³

1982

Plant Physiol.

View full text Add to dashboard Cite

“…However, there are a number of factors that could give rise to spurious GOGAT activity. Reduced activity could result from inactivation during extraction; the enzyme is unstable, with a reported activity loss of 2% h-l at 0 "C (Robertson et al, 1975). Farnden & Robertson (1980) recommend the inclusion of high levels of reducing agents, and Boland & Benny (1977) reported that the use of Tris buffers decreased the stability of their preparation.…”

Section: Results a N D Discussionmentioning

confidence: 99%

“…Two pathways for ammonium assimilation have been identified in bacteria (Tempest et al, 1970;Miller & Stadtman, 1972), plants (Robertson et al, 1975;Boland & Benny, 1977), yeasts and filamentous fungi (Lara et al, 1982;Kusnan et al, 1987). In the first pathway, glutamate dehydrogenase (GDH) catalyses the reaction : Ammonium + 2-oxoglutarate + NAD(P)H -+ glutamate + NAD(P)+ Fungi possess both an NAD+-dependent and an NADP+-dependent GDH; the latter catalyses the anabolic reaction (Goldin & Frieden, 1974).…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, GDH activity may be insufficient for assimilation when the internal ammonium concentration is low. The GS/GOGAT pathway constitutes the main route of ammonium assimilation in plants (Robertson et al, 1975;Miflin & Lea, 1977), Escherichia coli (Miller & Stadtman, 1972) and Rhizobium (Osburne & Signer, 1980). The relative importance of the two pathways in fungi is less clear.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ammonium Assimilation by Candida albicans and Other Yeasts: Evidence for Activity of Glutamate Synthase

et al. 1989

View full text Add to dashboard Cite

Activities and properties of the ammonium assimilation enzymes NADP+-dependent glutamate dehydrogenase (GDH), glutamate synthase (GOGAT) and glutamine synthetase (GS) were determined in batch and continuous cultures of Candida albicans. NADP+-dependent GDH activity showed allosteric kinetics, with an So.s for 2-oxoglutarate of 7.5 mM and an apparent K , for ammonium of 5-0 mM. GOGAT activity was affected by the buffer used for extraction and assay, but in phosphate buffer, kinetics were hyperbolic, yielding K , values for glutamine of 750 p~ and for 2-oxoglutarate of 65 p~. The enzymes GOGAT and NADP+-dependent GDH were also assayed in batch cultures of Saccharomyces cerevisiae and three other pathogenic Candida spp. : Candida tropicalis, Candida pseudotropicalis and Candida parapsilosis. Evidence is presented that GSlGOGAT is a major pathway for ammonium assimilation in Candida albicans and that this pathway is also significant in other Candida species.

show abstract

Induction of glutamate synthase during nodule development in lupin

Cited by 98 publications

References 26 publications

Nitrogen Nutrition and Xylem Transport of Nitrogen in Ureide-producing Grain Legumes

Nitrogen Nutrition and Xylem Transport of Nitrogen in Ureide-producing Grain Legumes

Glutamate Synthase Isoforms in Rice

Ammonium Assimilation by Candida albicans and Other Yeasts: Evidence for Activity of Glutamate Synthase

Contact Info

Product

Resources

About