Skip Navigation

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
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 Request Permissions
Google Scholar
Right arrow Articles by Mayer, M. J.
Right arrow Articles by Michael, A. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mayer, M. J.
Right arrow Articles by Michael, A. J.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

J. Biochem, 2003, Vol. 134, No. 5 765-772
© 2003 Japanese Biochemical Society

BIOCHEMISTRY

Polyamine Homeostasis in Transgenic Plants Overexpressing Ornithine Decarboxylase Includes Ornithine Limitation

Melinda J. Mayer and Anthony J. Michael*

Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, United Kingdom

It was reported recently that overexpression of human ornithine decarboxylase (ODC) cDNA in transgenic rice plants resulted in increased steady-state concentration of polyamines, i.e., enough biosynthetic control is invested at this step to enable adjustment of polyamine levels. To investigate critically whether constitutive overexpression of ODC is sufficient to control steady-state polyamine levels, we expressed an ODC cDNA from Datura stramonium in transgenic tobacco plants. Transgenic progeny of self-fertilised primary transformants exhibited increases in ODC activity of 25-fold in leaves and 5-fold in flower buds. However, the increase in putrescine levels was only 1.5- to 2.1-fold in leaves and 1.1- to 1.3-fold in flower buds. Emphatically, no changes to spermidine or spermine steady-state levels or to soluble or insoluble hydroxycinnamic acid-conjugated polyamines were observed. Ornithine feeding to cell suspension cultures derived from the transgenic plants indicated that putrescine accumulation was limited in part by ornithine availability. These results demonstrate that a large increase in the capacity of the tobacco plants to decarboxylate ornithine does not result in a comparable increase in the level of free or conjugated polyamines. Plant polyamine homeostatic mechanisms efficiently accommodate increased ODC activity, suggesting that polyamine biosynthetic control is invested at multiple interdependent steps.

* To whom correspondence should be addressed. Tel: +44-1603 255356, Fax: +44-1603 507723, E-mail: tony.michael{at}bbsrc.ac.uk


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




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.