FROM CELL-GROWTH TO LEAF GROWTH .2. SIMULATION OF A FILE OF CELLS

Certain plant parts have cells arranged end to end in more or less distinct files (e.g., monocot leaves, roots, filamentous algae). Modeling the growth and development of such files of cells can give us insights into processes governing cell division and cell expansion. The objectives of this research were to construct a cell-based model of a growing file of cells and to examine the effects of the daughter ratio vs. time function on the growth of the file. The file is considered to be a group of cells along the length of a monocot leaf. Cell expansion is described by water Bus equations. Cell division is determined by a daughter ratio vs. time function. The daughter ratio is defined as the proportion of cells that remain proliferative (capable of further division) after each cell division event. Outputs from the model include the elongation rate of the entire file, the growth rate distribution along the file, and the proliferative fractions for groups of cells along the file. Outputs are compared with field measurements of leaf elongation in sorghum [Sorghum bicolor (L.) Moench] plants. The model overestimates the length of the expanding zone compared with the field measurements. There is close agreement between model outputs and field measurements of relative growth rates along expanding portions of leaves and estimated proliferative fractions of expanding leaves. The effects of using different daughter ratio vs. time functions on model outputs are also examined.