Integrative Plant Physiology
Raghunandan, Janhavi , Jagendorf, Andre T , Turgeon, Robert , Ayre, Brian G. .
Metabolic engineering and transport properties of raffinose family oligosaccharides.
The transport of photoassimilate from source leaves to sink tissues via the phloem is essential for plant growth and development. The common transport sugars in plants are sucrose, sugar alcohols (polyols) and raffinose family oligosaccharides (RFOs). How these sugars are initially loaded into the phloem has received much attention, but their fate during transport is poorly understood. In plants that transport predominantly sucrose, carbohydrate partitioning between the phloem and lateral tissues appears to be mediated, at least in part, by sucrose-proton symporters. However, in plants that transport predominantly RFOs, no analogous mechanism for RFO partitioning has been identified. To address the fate of RFOs in the phloem, we employed metabolic engineering to synthesize the trisaccharide raffinose and the tetrasaccharide stachyose specifically in the phloem of Arabidopsis thaliana, a plant that normally transports predominantly sucrose. Of the genes utilized, GALACTINOL SYNTHASE is a phloem-specific, full-length gene from Cucumis melo (AF249912, AY077642), and RAFFINOSE SYNTHASE and STACHYOSE SYNTHASE are cDNAs derived from leaves of Cucumis sativus (AF073744) and Alonsoa meridionalis (AJ487030), respectively. The concentration of raffinose and stachyose in engineered Arabidopsis is comparable to that observed in Coleus blumei. Our efforts to characterize RFO transport properties will be reported.
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Ayre Lab Homepage
1 - University of North Texas, Department of Biological Sciences
2 - Cornell University, Department of Plant Biology
3 - University of North Texas, Department of Biological Sciences, 1504 W. Mulberry, SRB Rm 120, P.O. Box 305220, Denton, TX, 76203, USA
raffinose family oligosaccharides
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM