Endoreduplication In Orchid Flowers
HC Lee and TY LinDepartment of Life Science & Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, 30013, Taiwan, Republic of China
Endoreduplication, a process to amplify nuclear DNA without cell division, is widespread in plants. This study aims to formulate the endoreduplication process as a dynamic system using orchid flowers with a slow growth rate. We analyzed ploidy levels during flower development and propose an improved model to describe the relationship between endoreduplication and cell growth. Our model combines a logistic growth model with an endoreduplication model of Schweizer et al. (1995). We found that using the Fermi function to describe the transition rates from one C-value to next higher one significantly improved simulation of changes in growth and endoreduplication. The growth rate, endoreduplication transition rates, and nuclei number of each C-value level at different developmental stages were computed. Our results indicate that cells with higher C-values have lower transition rates and lower potential for further endoreduplication, and that the time that endoreduplication stops is when flower fresh weight ceases to increase. In addition, average cell fresh weight is positively correlated with average C-value, implying that endoreduplication might be a major driving force for cell growth.
1. Schweizer L et al. (1995). Proceedings of the National Academy of Science USA 92: 7070-7074.