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First published online September 24, 2004; 10.1104/pp.104.044131 Plant Physiology 136:3333-3340 (2004) © 2004 American Society of Plant Biologists Starch Division and Partitioning. A Mechanism for Granule Propagation and Maintenance in the Picophytoplanktonic Green Alga Ostreococcus tauri1,[w]Laboratoire de Chimie Biologique Unité Mixte de Recherche 8576 du Centre National de la Recherche Scientifique, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq cedex, France (J.-P.R., F.W., M.-C.S., D.D., C.D., S.B.); Observatoire océanologique, laboratoire Arago, Unité Mixte de Recherche 7628 Centre National de la Recherche Scientifique-Université Paris VI, BP 44, 66651 Banyuls-sur-mer cedex, France (E.D., B.F., F.C., H.M.); Institut de Génétique Humaine, Unité Propre de Recherche Centre National de la Recherche Scientifique 1142, 34396 Montpellier cedex 5, France (C.F.); Institut National de la Recherche Agronomique, Centre de Recherches Agroalimentaires, BP71627, 44316 Nantes cedex 03, France (A.B.); and Department of Plant Systems Biology, Ghent University, VIB, B9052 Gent, Belgium (S.R.)
Whereas Glc is stored in small-sized hydrosoluble glycogen particles in archaea, eubacteria, fungi, and animal cells, photosynthetic eukaryotes have resorted to building starch, which is composed of several distinct polysaccharide fractions packed into a highly organized semicrystalline granule. In plants, both the initiation of polysaccharide synthesis and the nucleation mechanism leading to formation of new starch granules are currently not understood. Ostreococcus tauri, a unicellular green alga of the Prasinophyceae family, defines the tiniest eukaryote with one of the smallest genomes. We show that it accumulates a single starch granule at the chloroplast center by using the same pathway as higher plants. At the time of plastid division, we observe elongation of the starch and division into two daughter structures that are partitioned in each newly formed chloroplast. These observations suggest that in this system the information required to initiate crystalline polysaccharide growth of a new granule is contained within the preexisting polysaccharide structure and the design of the plastid division machinery.
1 This work was supported by the French Ministry of Education, by the Centre National de la Recherche Scientifique, and by the Génopole Languedoc-Roussillon. [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.044131. * Corresponding author; e-mail steven.ball{at}univ-lille1.fr; fax 33320436555. Received April 5, 2004; returned for revision May 11, 2004; accepted May 11, 2004. This article has been cited by other articles:
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