Document Detail


Increasing amino acid supply in pea embryos reveals specific interactions of N and C metabolism, and highlights the importance of mitochondrial metabolism.
MedLine Citation:
PMID:  18494854     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The application of nitrogen to legumes regulates seed metabolism and composition. We recently showed that the seed-specific overexpression of amino acid permease VfAAP1 increases amino acid supply, and the levels of N and protein in the seeds. Two consecutive field trials using Pisum sativum AAP1 lines confirmed increases in the levels of N and globulin in seed; however, compensatory changes of sucrose/starch and individual seed weight were also observed. We present a comprehensive analysis of AAP1 seeds using combinatorial transcript and metabolite profiling to monitor the effects of nitrogen supply on seed metabolism. AAP1 seeds have increased amino acids and stimulated gene expression associated with storage protein synthesis, maturation, deposition and vesicle trafficking. Transcript/metabolite changes reveal the channelling of surplus N into the transient storage pools asparagine and arginine, indicating that asparagine synthase is transcriptionally activated by high N levels and/or C limitation. Increased C-acceptor demand for amino acid synthesis, resulting from elevated levels of N in seeds, initiates sucrose mobilization and sucrose-dependent pathways via sucrose synthase, glycolysis and the TCA cycle. The AAP1 seeds display a limitation in C, which leads to the catabolism of arginine, glutamic acid and methionine to putrescine, beta-alanine and succinate. Mitochondria are involved in the coordination of C/N metabolism, with branched-chain amino acid catabolism and a gamma-amino-butyric acid shunt. AAP1 seeds contain higher levels of ABA, which is possibly involved in storage-associated gene expression and the N-dependent stimulation of sucrose mobilization, indicating that a signalling network of C, N and ABA is operating during seed maturation. These results demonstrate that legume seeds have a high capacity to regulate N:C ratios, and highlight the importance of mitochondria in the control of N-C balance and amino acid homeostasis.
Authors:
Kathleen Weigelt; Helge Küster; Ruslana Radchuk; Martin Müller; Heiko Weichert; Aaron Fait; Alisdair R Fernie; Isolde Saalbach; Hans Weber
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-05-20
Journal Detail:
Title:  The Plant journal : for cell and molecular biology     Volume:  55     ISSN:  1365-313X     ISO Abbreviation:  Plant J.     Publication Date:  2008 Sep 
Date Detail:
Created Date:  2008-09-10     Completed Date:  2008-11-05     Revised Date:  2013-05-20    
Medline Journal Info:
Nlm Unique ID:  9207397     Medline TA:  Plant J     Country:  England    
Other Details:
Languages:  eng     Pagination:  909-26     Citation Subset:  IM    
Affiliation:
Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Gatersleben, Germany.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Transport Systems / genetics,  metabolism
Amino Acids / metabolism*
Carbon / metabolism*
Gene Expression Profiling
Gene Expression Regulation, Plant
Genes, Mitochondrial
Genes, Plant
Homeostasis
Mitochondria / metabolism*
Nitrogen / metabolism*
Oligonucleotide Array Sequence Analysis
Peas / embryology,  genetics,  metabolism*
Plant Proteins / genetics,  metabolism
Plants, Genetically Modified / embryology,  genetics,  metabolism
RNA, Plant / genetics
Seeds / embryology,  genetics,  metabolism
Sucrose / metabolism
Transcription Factors / genetics
Chemical
Reg. No./Substance:
0/Amino Acid Transport Systems; 0/Amino Acids; 0/Plant Proteins; 0/RNA, Plant; 0/Transcription Factors; 57-50-1/Sucrose; 7440-44-0/Carbon; 7727-37-9/Nitrogen

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


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