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First published online November 23, 2005; 10.1104/pp.105.068767 Plant Physiology 139:1984-1994 (2005) © 2005 American Society of Plant Biologists Cell Expansion and Endoreduplication Show a Large Genetic Variability in Pericarp and Contribute Strongly to Tomato Fruit Growth1Unité Mixte de Recherche 619 Physiologie et Biotechnologies Végétales, Institut National de la Recherche Agronomique, Université Bordeaux 1, Université Victor Segalen Bordeaux 2, 33883 Villenave d'Ornon, France (C.C., W.Y.R., N.F., L.B., J.-P.C., J.-P.R.); and Unité de Recherche Génétique et Amélioration des Fruits et Légumes, Institut National de la Recherche Agronomique, 84143 Montfavet, France (M.C.)
Postanthesis growth of tomato (Solanum lycopersicon) as of many types of fruit relies on cell division and cell expansion, so that some of the largest cells to be found in plants occur in fleshy fruit. Endoreduplication is known to occur in such materials, which suggests its involvement in cell expansion, although no data have demonstrated this hypothesis as yet. We have analyzed pattern formation, cell size, and ploidy in tomato fruit pericarp. A first set of data was collected in one cherry tomato line throughout fruit development. A second set of data was obtained from 20 tomato lines displaying a large weight range in fruit, which were compared as ovaries at anthesis and as fully grown fruit at breaker stage. A remarkable conservation of pericarp pattern, including cell layer number and cell size, is observed in all of the 20 tomato lines at anthesis, whereas large variations of growth occur afterward. A strong, positive correlation, combining development and genetic diversity, is demonstrated between mean cell size and ploidy, which holds for mean cell diameters from 10 to 350 µm (i.e. a 32,000-times volume variation) and for mean ploidy levels from 3 to 80 C. Fruit weight appears also significantly correlated with cell size and ploidy. These data provide a framework of pericarp patterning and growth. They strongly suggest the quantitative importance of polyploidy-associated cell expansion as a determinant of fruit weight in tomato.
1 This work was supported by Région Aquitaine (contract no. 2004 0307002A). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jean-Pierre Renaudin (jean-pierre.renaudin{at}bordeaux.inra.fr). Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.068767. * Corresponding author; e-mail jean-pierre.renaudin{at}bordeaux.inra.fr; fax 335557125541. Received July 24, 2005; returned for revision September 25, 2005; accepted September 28, 2005. This article has been cited by other articles:
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