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. 1988 Jan;86(1):204–207. doi: 10.1104/pp.86.1.204

Pathways of Nitrogen Assimilation in Cowpea Nodules Studied using 15N2 and Allopurinol 1

Craig A Atkins 1, Paul J Storer 1, John S Pate 1
PMCID: PMC1054455  PMID: 16665867

Abstract

In the presence of 0.5 millimolar allopurinol (4-hydroxypyrazolo [3,4-d]pyrimidine), an inhibitor of NAD:xanthine oxidoreductase (EC 1.2.3.2), intact attached nodules of cowpea (Vigna unguiculata L. Walp. cv Vita 3) formed [15N]xanthine from 15N2 at rates equivalent to those of ureide synthesis, confirming the direct assimilation of fixed nitrogen into purines. Xanthine accumulated in nodules and was exported in increasing amounts in xylem of allopurinol-treated plants. Other intermediates of purine oxidation, de novo purine synthesis, and ammonia assimilation did not increase and, over the time course of experiments (4 hours), allopurinol had no effect on nitrogenase (EC 1.7.99.2) activity. Negligible 15N-labeling of asparagine from 15N2 was observed, suggesting that the significant pool (up to 14 micromoles per gram of nodule fresh weight) of this amide in cowpea nodules was not formed directly from fixation but may have accumulated as a consequence of phloem delivery.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Atkins C. A., Pate J. S., Griffiths G. J., White S. T. Economy of Carbon and Nitrogen in Nodulated and Nonnodulated (NO(3)-grown) Cowpea [Vigna unguiculata (L.) Walp.]. Plant Physiol. 1980 Nov;66(5):978–983. doi: 10.1104/pp.66.5.978. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Atkins C. A., Ritchie A., Rowe P. B., McCairns E., Sauer D. De Novo Purine Synthesis in Nitrogen-Fixing Nodules of Cowpea (Vigna unguiculata [L.] Walp.) and Soybean (Glycine max [L.] Merr.). Plant Physiol. 1982 Jul;70(1):55–60. doi: 10.1104/pp.70.1.55. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Atkins C. A., Shelp B. J., Storer P. J. Purification and properties of inosine monophosphate oxidoreductase from nitrogen-fixing nodules of cowpea (Vigna unguiculata L. Walp). Arch Biochem Biophys. 1985 Feb 1;236(2):807–814. doi: 10.1016/0003-9861(85)90687-3. [DOI] [PubMed] [Google Scholar]
  4. Boland M. J., Schubert K. R. Purine biosynthesis and catabolism in soybean root nodules: incorporation of 14C from 14CO2 into xanthine. Arch Biochem Biophys. 1982 Feb;213(2):486–491. doi: 10.1016/0003-9861(82)90574-4. [DOI] [PubMed] [Google Scholar]
  5. Fujihara S., Yamaguchi M. Effects of Allopurinol [4-Hydroxypyrazolo(3,4-d)Pyrimidine] on the Metabolism of Allantoin in Soybean Plants. Plant Physiol. 1978 Jul;62(1):134–138. doi: 10.1104/pp.62.1.134. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Herridge D. F., Atkins C. A., Pate J. S., Rainbird R. M. Allantoin and Allantoic Acid in the Nitrogen Economy of the Cowpea (Vigna unguiculata [L.] Walp.). Plant Physiol. 1978 Oct;62(4):495–498. doi: 10.1104/pp.62.4.495. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Pate J. S., Peoples M. B., Atkins C. A. Spontaneous Phloem bleeding from cryopunctured fruits of a ureide-producing legume. Plant Physiol. 1984 Mar;74(3):499–505. doi: 10.1104/pp.74.3.499. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Rainbird R. M., Thorne J. H., Hardy R. W. Role of amides, amino acids, and ureides in the nutrition of developing soybean seeds. Plant Physiol. 1984 Feb;74(2):329–334. doi: 10.1104/pp.74.2.329. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Reynolds P. H., Boland M. J., Blevins D. G., Schubert K. R., Randall D. D. Enzymes of amide and ureide biogenesis in developing soybean nodules. Plant Physiol. 1982 Jun;69(6):1334–1338. doi: 10.1104/pp.69.6.1334. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Shelp B. J., Atkins C. A. Role of Inosine Monophosphate Oxidoreductase in the Formation of Ureides in Nitrogen-Fixing Nodules of Cowpea (Vigna unguiculata L. Walp.). Plant Physiol. 1983 Aug;72(4):1029–1034. doi: 10.1104/pp.72.4.1029. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Triplett E. W. Two indirect methods for detecting ureide synthesis by nodulated legumes. Plant Physiol. 1986 Jun;81(2):566–571. doi: 10.1104/pp.81.2.566. [DOI] [PMC free article] [PubMed] [Google Scholar]

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