Allantoin and Allantoic Acid in the Nitrogen Economy of the Cowpea (Vigna unguiculata (L.) Walp.)

Allantoin and Allantoic Acid in the Nitrogen Economy of the Cowpea (Vigna unguiculata (L.) Walp.) The ureides, allantoin and allantoic acid, represented major fractions of the soluble nitrogen pool of nodulated plants of cowpea ( Vigna unguiculata (L.) Walp. cv. Caloona) throughout vegetative and reproductive growth. Stem and petioles were the principal sites of ureide accumulation, especially in early fruiting. Labeling studies using 14 CO 2 and 15 N 2 and incubation periods of 25 to 245 minutes indicated that synthesis of allantoin and allantoic acid in root nodules involved currently delivered photosynthate and recently fixed N, and that the ureides were exported from nodule to shoot via the xylem. From 60 to 80% of xylem-borne N consisted of ureides; the remainder was glutamine, asparagine, and amino acids. Allantoin predominated in the soluble N fraction of nodules and fruits, allantoin and allantoic acid were present in approximately equal proportions in xylem exudate, stems, and petioles. Extracts of the plant tissue fraction of nitrogen-fixing cowpea nodules contained glutamate synthase (EC 2.6.1.53 ) and glutamine synthetase (EC 6.3.1.2 ), but little activity of glutamate dehydrogenase (EC 1.4.1.3 ). High levels of uricase (EC 1.7.3.3 ) and allantoinase (EC 3.5.2.5 ) were also detected. Allantoinase but little uricase was found in extracts of leaflets, pods, and seeds. Balance sheets were constructed for production, storage, and utilization of ureide N during growth. Virtually all (average 92%) of the ureides exported from roots was metabolized on entering the shoot, the compounds being presumably used as N sources for protein synthesis. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png

Allantoin and Allantoic Acid in the Nitrogen Economy of the Cowpea (Vigna unguiculata (L.) Walp.)

Loading next page...
 
/lp/american-society-of-plant-biologist/allantoin-and-allantoic-acid-in-the-nitrogen-economy-of-the-cowpea-8XgKa9q5f1
Publisher
American Society of Plant Biologist
Copyright
Copyright © 1978 by the American Society of Plant Biologists
ISSN
1532-2548
eISSN
0032-0889
DOI
10.1104/pp.62.4.495
Publisher site
See Article on Publisher Site

Abstract

The ureides, allantoin and allantoic acid, represented major fractions of the soluble nitrogen pool of nodulated plants of cowpea ( Vigna unguiculata (L.) Walp. cv. Caloona) throughout vegetative and reproductive growth. Stem and petioles were the principal sites of ureide accumulation, especially in early fruiting. Labeling studies using 14 CO 2 and 15 N 2 and incubation periods of 25 to 245 minutes indicated that synthesis of allantoin and allantoic acid in root nodules involved currently delivered photosynthate and recently fixed N, and that the ureides were exported from nodule to shoot via the xylem. From 60 to 80% of xylem-borne N consisted of ureides; the remainder was glutamine, asparagine, and amino acids. Allantoin predominated in the soluble N fraction of nodules and fruits, allantoin and allantoic acid were present in approximately equal proportions in xylem exudate, stems, and petioles. Extracts of the plant tissue fraction of nitrogen-fixing cowpea nodules contained glutamate synthase (EC 2.6.1.53 ) and glutamine synthetase (EC 6.3.1.2 ), but little activity of glutamate dehydrogenase (EC 1.4.1.3 ). High levels of uricase (EC 1.7.3.3 ) and allantoinase (EC 3.5.2.5 ) were also detected. Allantoinase but little uricase was found in extracts of leaflets, pods, and seeds. Balance sheets were constructed for production, storage, and utilization of ureide N during growth. Virtually all (average 92%) of the ureides exported from roots was metabolized on entering the shoot, the compounds being presumably used as N sources for protein synthesis.

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off