Poster: Metabolic Engineering

Abs # 1009: Control of carbohydrate metabolism in developing seeds of Arabidopsis

Presenter:	Benning, Christoph , benning@msu.edu
Authors	Benning, Christoph  (A)   Cernac, Alex  (A)   Wakao, Setsuko  (A)
Affiliations:	(A): Dept. of Biochemistry and Molecular Biology, Michigan State University
Web Site:	http://: www.bch.msu.edu

Developing seeds of Arabidopsis import photosynthate in the form of sucrose and convert it into precursors of fatty acid biosynthesis. Metabolic pathways involved in this process are likely to be glycolysis and possibly the oxidative pentose phosphate pathway (OPPP). Most efforts to engineer oil biosynthesis in oil crops have focused on fatty acid biosynthesis and fatty acid modification. However, to increase the flux of metabolites into oil biosynthesis and enhance oil yield, the supply of carbon precursors as well as reducing equivalents has to be considered. A mutant which is deficient in the regulation of oil biosynthesis in Arabidopsis is wrinkled1 (wri1). We recently identified the WRI1 gene by map based cloning. It encodes a putative transcription factor of the AP2/EREBP class. Biochemical and gene expression analysis of the mutant suggest that this putative transcription factor has a narrow set of target genes encoding enzymes involved in carbohydrate metabolism in developing seeds. Experiments are under way to understand the regulation of WRI1 expression itself. To explore the role of the OPPP in developing seeds for the supply of reducing equivalents, a genomic effort to characterize all six glucose-6-P dehydrogenases (G6PDH) encoding genes of Arabidopsis has been undertaken. Three of the six cytosolic and plastidic isoforms are present in developing seeds and their importance for oil biosynthesis is under investigation.