A model describing cell polyploidization in tissues of growing fruit as related to cessation of cell proliferation

Abstract

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 tau, the proportion of cells proceeding through division depends on a constant parameter rho and on the progressive decline of the proliferating capacity . 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 sigma describes the proportion of cells that moves from one to the next class of DNA content after each lapse of time tauE, 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.

New Insights into the Control of Endoreduplication: Endoreduplication Could Be Driven by Organ Growth in Arabidopsis Leaves

“…For example, 16C or 32C cells are often reported in leaves, roots, and hypocotyls of Arabidopsis Cookson et al, 2006), whereas in tomato (Solanum lycopersicum) fruits, DNA content can reach up to 256C (Bertin et al, 2007). Here, the ploidy could reach up to 64C in leaves of a large number of genotypes among the 200 studied.…”

Ultrastructure of the Epidermal Cell Wall and Cuticle of Tomato Fruit (Solanum lycopersicum L.) during Development

“…Whereas the first is mostly limited to early stages of development, cell expansion is responsible for most of an organ's growth and mainly occurs after cell division has ceased. In cherry tomatoes, transition between division and expansion occurs around 11 to 14 daa (Bertin et al, 2007;España et al, 2014). Several transcriptional factors involved in the regulation of cell division and expansion have been identified (Anastasiou and Lenhard, 2007).…”

Biochemical factors contributing to tomato fruit sugar content: a review

“…There are five recognisable phases [14]: anthesis, fertilisation, cell division, cell expansion and ripening, with some overlap between stages. Cell division occurs in the newly-formed fruit for 7-10 days [15], or in large-fruited cultivars for 20 days [16], after which the final fruit cell number is set. The cells then expand from 10-40 days post-anthesis (DPA) due to the vacuolar storage of photosynthate and water, leading to a more than ten-fold increase in fruit size [14,17].…”