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Abstract Detail

Seed Biology

Nguyen, Ha [2], Rollet, H [2], Häusler, R.E [1], Rutten, T [2], Göbel, C [3], Feussner, I [3], Radchuk, R [2], Tewes, A. [2], Claus, B [2], Klukas, C [2], Linemann, U [4], Weber, H [2], Wobus, U [2], Borisjuk, L [2].

Antisense inhibition of the plastidial glucose-6-phosphate/phosphate translocator in Vicia seeds shifts cellular differentiation and promotes protein storage.

The glucose-6-phosphate/phosphate translocator (GPT) acts as an importer of carbon into the plastid. Despite the potential importance of GPT for storage in crop seeds, its regulatory role in biosynthetic pathways active during seed development is poorly understood. We have isolated GPT1 from Vicia narbonensis and studied its role in seed development using a transgenic approach, based on the seed-specific promoter LeB4. GPT1 is highlyexpressed in vegetative sink tissues, flowers and young seeds. In the embryo, the localised up-regulation of GPT1 at theonset of storage coincides with the onset of starch accumulation. In transgenic embryos expressing antisense GPT1, the specific transport rate of glucose-6-phosphate was decreased by up to 55% of the wild type level. Furthermore, amyloplasts developed later and were smaller in size, while the expression levels of plastid-specific translocators and other proteins involved in starch biosynthesis were decreased. Metabolite analysis and stable isotope labelling demonstrated that starch biosynthesis wasalso reduced, although protein biosynthesis increased. This metabolic shift wascharacterized by an up-regulation of genes related to nitrogen uptake and protein storage, greater morphological variation of the protein-storing vacuoles, and an up to 30% higher crude protein content ofmature transgenic seeds. These findings provide evidence that (1) the prevailing level of GPT1abundance/activity is rate-limiting for the synthesis of starch in developing seeds, (2) GPT1 exerts a controlling function for assimilate partitioning intostorage protein, and (3) GPT1 is essential for the differentiation of embryonic plastids and seed maturation.

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1 - Botanisches Institut der Universität zu Köln, 50931 Köln, Germany
2 - Leibniz Institute of Plant Genetics and Crop Plant Research, 3 Corrensstrasse, Gatersleben, D-06466, Germany
3 - Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Biochemistry, Justus-von-Liebig-Weg 11, Goettingen, D-37077, Germany
4 - Sungene GmbH, 06466 Gatersleben, Germany

function of GPT1 in seed development.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P29012
Abstract ID:847

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