title: Endoreduplication and fruit growth in tomato: evidence in favour of the karyoplasmic ratio theory.
abstract: The growth of a plant organ depends upon the developmental processes of cell division and cell expansion. The activity of cell divisions sets the number of cells that will make up the organ; the cell expansion activity then determines its final size. Among the various mechanisms that may influence the determination of cell size, endopolyploidy by means of endoreduplication appears to be of great importance in plants. Endoreduplication is widespread in plants and supports the process of differentiation of cells and organs. Its functional role in plant cells is not fully understood, although it is commonly associated with ploidy-dependent cell expansion. During the development of tomato fruit, cells from the (fleshy) pericarp tissue become highly polyploid, reaching a DNA content barely encountered in other plant species (between 2C and 512C). Recent investigations using tomato fruit development as a model provided new data in favour of the long-standing karyoplasmic ratio theory, stating that cells tend to adjust their cytoplasmic volume to the nuclear DNA content. By establishing a highly structured cellular system where multiple physiological functions are integrated, endoreduplication does act as a morphogenetic factor supporting cell growth during tomato fruit development.
authors.affiliation: INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France chevalie@bordeaux.inra.fr.
authors.forename: Christian
authors.initials: C
authors.lastname: Chevalier
authors.affiliation: INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Bourdon
authors.affiliation: INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Pirrello
authors.affiliation: INRA, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France CNRS, Bordeaux Imaging Center, UMS 3420, F-33000 Bordeaux, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Cheniclet
authors.affiliation: University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gévaudant
authors.affiliation: University of Bordeaux, UMR 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Frangne
mesh_terms: D002455:Cell Division; D048429:Cell Size; D062951:Endoreduplication; D018551:Solanum lycopersicum / Q000166:cytology / Q000254:growth & development*
keywords: Cell cycle control; cell size; endoreduplication; fruit; growth; karyoplasmic ratio theory; tomato.