Document Detail

Bidirectional exchange of amino compounds between phloem and xylem during long-distance transport in Norway spruce trees (Picea abies [L.] Karst).
MedLine Citation:
PMID:  12709485     Owner:  NLM     Status:  MEDLINE    
14C-Gln, (14)C-Asp, (15)N-Gln, and (15)N-Asp were fed to cut tips of 2- or 3-year-old needles of spruce twigs, still attached to the tree. After incubation, distribution of the radiolabel and (15)N enrichment was studied in needles, bark and wood tissues of girdled twigs and untreated controls. Analysis of the twig tissues showed that between 22% and 26% of the total amount of the tracers applied had been taken up. Since export out of the application segment and distribution between needles, bark and wood was comparable for (14)C and (15)N tracer, it was concluded that, mainly the amino compounds that had been fed were subject to long- distance transport within the plant and supplied the new sprout with nitrogen. Asp was exported to a greater extent to developing needles compared with Gln. This difference in export between the two amino compounds applied may be explained by the different pool sizes of Gln and Asp in xylem and phloem or differences in xylem and phloem loading. Girdling of the stem showed that the transport of reduced nitrogen compounds from older needle generations to current-year needles proceeded in both xylem and phloem. In addition, an intensive bidirectional exchange of Gln and Asp between xylem and phloem was observed during long-distance transport.
Arthur Gessler; Paul Weber; Stephan Schneider; Heinz Rennenberg
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of experimental botany     Volume:  54     ISSN:  0022-0957     ISO Abbreviation:  J. Exp. Bot.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-04-23     Completed Date:  2003-07-25     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  9882906     Medline TA:  J Exp Bot     Country:  England    
Other Details:
Languages:  eng     Pagination:  1389-97     Citation Subset:  IM    
Institut für Forstbotanik und Baumphysiologie, Professur für Baumphysiologie, Albert-Universität Freiburg, Georges-Köhler-Allee Geb 053/054, D-79110 Freiburg i. Br., Germany.
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MeSH Terms
Aspartic Acid / metabolism*,  pharmacology
Biological Transport / drug effects,  physiology
Carbon Radioisotopes / metabolism
Glutamic Acid / metabolism*,  pharmacology
Nitrogen Isotopes / metabolism
Picea / metabolism*
Plant Bark / metabolism
Plant Leaves / metabolism
Plant Stems / metabolism
Plant Structures / metabolism*
Reg. No./Substance:
0/Carbon Radioisotopes; 0/Nitrogen Isotopes; 56-84-8/Aspartic Acid; 56-86-0/Glutamic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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