Purine synthesis and catabolism in soybean seedlings. The biogenesis of ureides [Allantoin and allantoic acid]

The ureides, allantoin and allantoic acid, are the major nitrogenous substances transported within the xylem of N2-fixing soybeans (Glycine max L. Merr. cv Amsoy 71). The ureides accumulated in the cotyledons, roots and shoots of soybean seedlings inoculated with Rhizobium or grown in the presence o...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1984-08, Vol.75 (4), p.1104-1110
Main Authors: Deborah A. Polayes, Schubert, Karel R.
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Biological and medical sciences
Cotyledons
Economic plant physiology
Fundamental and applied biological sciences. Psychology
Metabolism
Metabolism. Physicochemical requirements
Nitrates
Nitrogen metabolism and other ones (excepting carbon metabolism)
Nutrition. Photosynthesis. Respiration. Metabolism
Plant physiology and development
Plant roots
Plants
Purines
Radioactive decay
Seedlings
Soybeans
Uric acid
Xanthines
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Summary:The ureides, allantoin and allantoic acid, are the major nitrogenous substances transported within the xylem of N2-fixing soybeans (Glycine max L. Merr. cv Amsoy 71). The ureides accumulated in the cotyledons, roots and shoots of soybean seedlings inoculated with Rhizobium or grown in the presence of 10 millimolar nitrate. The patterns of activity for uricase and allantoinase, enzymes involved in ureide synthesis, were positively correlated with the accumulation of ureides in the roots and cotyledons. Allopurinol and azaserine inhibited ureide production in 3-day-old cotyledons while no inhibition was observed in the roots. Incubation of 4-day-old seedlings with [14C]serine indicated that in the cotyledons ureides arose via de novo synthesis of purines. The source of ureides in both 3- and 4-day-old roots was probably the cotyledons. The inhibition of ureide accumulation by allopurinol but not azaserine in 8-day-old cotyledons suggested that ureides in these older cotyledons arose via nucleotide breakdown. Incubation of 8-day-old plants with [14C]serine suggested that the roots had acquired the capability to synthesize ureides via de novo synthesis of purines. These data indicate that both de novo purine synthesis and nucleotide breakdown are involved in the production of ureides in young soybean seedlings.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.75.4.1104