Bertin, N., UR1115 Plantes et Systèmes de Culture Horticoles, INRA, F-84000 Avignon, France
Lecomte, A., UR1115 Plantes et Systèmes de Culture Horticoles, INRA, F-84000 Avignon, France
Brunel, B., UR1115 Plantes et Systèmes de Culture Horticoles, INRA, F-84000 Avignon, France
Fishman, S., Department of Statistics and Operations Research, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Génard, M., UR1115 Plantes et Systèmes de Culture Horticoles, INRA, F-84000 Avignon, France

Endoreduplication is a phenomenon, widespread among plants, which consists of an incomplete cell cycle without mitosis and leads to the increase of the nuclear DNA content. In this work, a model was developed describing cell proliferation and DNA endoreduplication over the whole fruit development, from the pre-anthesis period until maturation. In each mitotic cycle of duration τ, the proportion of cells proceeding through division depends on a constant parameter ρ and on the progressive decline of the proliferating capacity θ. The non-dividing cells may either stop the reduplication fully, or switch to repeated syntheses of DNA without cell division, resulting in cell endoreduplication. A single constant parameter σ describes the proportion of cells that moves from one to the next class of DNA content after each lapse of time τE, considered to be the minimum time required for an endocycle. The model calculates the total number of cells and their distribution among eight classes of ploidy level. The dynamic patterns of cell proliferation and ploidy were compared with those obtained experimentally on two contrasting tomato genotypes. The approach developed in this model should allow the future integration of new knowledge concerning the genetic and environmental control of the switch from complete to incomplete cell cycle. © The Author [2007]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.