Skip Navigation



JXB Advance Access published online on December 20, 2004
Journal of Experimental Botany, doi:10.1093/jxb/eri046
This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrowOA All Versions of this Article:
56/412/577    most recent
eri046v1
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Hutchings, D.
Right arrow Articles by Emes, M. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hutchings, D.
Right arrow Articles by Emes, M. J.
Agricola
Right arrow Articles by Hutchings, D.
Right arrow Articles by Emes, M. J.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Journal of Experimental Botany © Society for Experimental Biology 2004; all rights reserved
Received August 31, 2004
Accepted October 6, 2004

RESEARCH PAPER

Fatty acid synthesis and the oxidative pentose phosphate pathway in developing embryos of oilseed rape (Brassica napus L.)

David Hutchings 1, Stephen Rawsthorne 2*, and Michael J. Emes 3

1 School of Biological Sciences, University of Manchester, 3.614 Stopford Building, Oxford Street, Manchester M13 9PT, UK
2 Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK
3 School of Biological Sciences, University of Manchester, 3.614 Stopford Building, Oxford Street, Manchester M13 9PT, UK; Present address: College of Biological Sciences, University of Guelph, Guelph, Ontario, N1G 2W1 Canada

* To whom correspondence should be addressed.
Stephen Rawsthorne, E-mail: steve.rawsthorne{at}bbsrc.ac.uk


  Abstract

The potential role of the plastidial oxidative pentose phosphate pathway (OPPP) in providing the NADPH for fatty acid synthesis in plastids from developing embryos of Brassica napus (L.) has been investigated. Measurements of distributions of enzyme activities in fractions obtained from homogenates of isolated embryos have revealed that the glucose 6-phosphate and 6-phosphogluconate dehydrogenases are present in both cytosol and plastid, as is ribose 5-phosphate isomerase. However, transketolase and transaldolase are most probably confined to the plastid, while ribulose 5-phosphate epimerase is essentially cytosolic, although a very small proportion of plastid-localized activity cannot be ruled out. The activity of the OPPP in intact plastids was measured by the release of 14CO2 from [1-14C]glucose 6-phosphate. Activity was detectable in the absence of electron sinks created by the addition of metabolites to the incubation media and was stimulated 1.3-, 3.2-, and 7.9-fold by the respective additions of glutamine plus 2-oxoglutarate, cofactors and substrates for fatty acid synthesis, or methyl viologen. An increase in OPPP activity in response to additions that are absolutely required for fatty acid synthesis in these isolated plastids provides direct evidence that these two processes are connected, most probably by NADP/NADPH metabolism. The OPPP activity with methyl viologen was more than twice that during fatty acid synthesis, suggesting that the latter is not limited by OPPP capacity. Light energy may also contribute to reductant provision and, consistent with the possibility of maintenance of a balance of NADPH from light and the OPPP, glucose 6-phosphate dehydrogenase activity in the isolated plastids was decreased by light or by DTT.

Keywords: Brassica napus; embryo; fatty acid synthesis; oxidative pentose phosphate pathway; plastid.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Plant Physiol.Home page
M. Hajduch, J. E. Casteel, K. E. Hurrelmeyer, Z. Song, G. K. Agrawal, and J. J. Thelen
Proteomic Analysis of Seed Filling in Brassica napus. Developmental Characterization of Metabolic Isozymes Using High-Resolution Two-Dimensional Gel Electrophoresis
Plant Physiology, May 1, 2006; 141(1): 32 - 46.
[Abstract] [Full Text] [PDF]

Home page
 J Exp BotHome page
R. Pleite, M. J. Pike, R. Garces, E. Martinez-Force, and S. Rawsthorne
The sources of carbon and reducing power for fatty acid synthesis in the heterotrophic plastids of developing sunflower (Helianthus annuus L.) embryos
J. Exp. Bot., May 1, 2005; 56(415): 1297 - 1303.
[Abstract] [Full Text] [PDF]


Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.