Document Detail

Mitochondria-driven changes in leaf NAD status exert a crucial influence on the control of nitrate assimilation and the integration of carbon and nitrogen metabolism.
MedLine Citation:
PMID:  16126851     Owner:  NLM     Status:  MEDLINE    
The Nicotiana sylvestris mutant, CMS, lacks the mitochondrial gene nad7 and functional complex I, and respires using low-affinity NADH (alternative) mitochondrial dehydrogenases. Here, we show that this adjustment of respiratory pathways is associated with a profound modification of foliar carbon-nitrogen balance. CMS leaves are characterized by abundant amino acids compared to either wild-type plants or CMS in which complex I function has been restored by nuclear transformation with the nad7 cDNA. The metabolite profile of CMS leaves is enriched in amino acids with low carbon/nitrogen and depleted in starch and 2-oxoglutarate. Deficiency in 2-oxoglutarate occurred despite increased citrate and malate and higher capacity of key anaplerotic enzymes, notably the mitochondrial NAD-dependent isocitrate dehydrogenase. The accumulation of nitrogen-rich amino acids was not accompanied by increased expression of enzymes involved in nitrogen assimilation. Partitioning of (15)N-nitrate into soluble amines was enhanced in CMS leaf discs compared to wild-type discs, especially in the dark. Analysis of pyridine nucleotides showed that both NAD and NADH were increased by 2-fold in CMS leaves. The growth retardation of CMS relative to the wild type was highly dependent on photoperiod, but at all photoperiod regimes the link between high contents of amino acids and NADH was observed. Together, the data provide strong evidence that (1) NADH availability is a critical factor in influencing the rate of nitrate assimilation and that (2) NAD status plays a crucial role in coordinating ammonia assimilation with the anaplerotic production of carbon skeletons.
Christelle Dutilleul; Caroline Lelarge; Jean-Louis Prioul; Rosine De Paepe; Christine H Foyer; Graham Noctor
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-08-26
Journal Detail:
Title:  Plant physiology     Volume:  139     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  2005 Sep 
Date Detail:
Created Date:  2005-09-16     Completed Date:  2006-01-23     Revised Date:  2010-09-21    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  64-78     Citation Subset:  IM    
Crop Performance and Improvement Division, Rothamsted Research, Harpenden, Hertfordshire, UK.
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MeSH Terms
Amides / metabolism
Amines / metabolism
Carbon / metabolism*
Cell Respiration
Gene Expression Profiling
Gene Expression Regulation, Enzymologic
Gene Expression Regulation, Plant
Mitochondria / metabolism*
Mitochondrial Proteins / genetics,  metabolism
NAD / metabolism*
Nitrates / metabolism*
Plant Leaves / genetics,  metabolism*
Plant Proteins / genetics,  metabolism
Pyrimidine Nucleotides / metabolism
Tobacco / genetics,  metabolism*
Reg. No./Substance:
0/Amides; 0/Amines; 0/Mitochondrial Proteins; 0/Nitrates; 0/Plant Proteins; 0/Pyrimidine Nucleotides; 53-84-9/NAD; 7440-44-0/Carbon

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