Genetic Control of Cell Division Patterns in Developing Plants

Understanding the control of the patterns and numbers of cell divisions in developing plants and animals is central to understanding the mechanisms of development. However, we know almost nothing about this control: we have no idea how a particular organ realizes its eventual cell number (and thus size) and have little idea of how the regional patterns of cell division that are a critical part of organogenesis are established or maintained. These problems can be studied in a very straightforward manner in flowering plant development: plants do not use the standard animal mechanisms of cell migration and migration of sheets of cells, and although plants use programmed cell death in many ways, they do not appear to use it to achieve appropriate cell numbers in developing organs or stem cell populations. Furthermore, plant cells do not slide or slip relative to one another. Organogenesis in flowering plants thus results almost entirely from patterned control of the numbers, places, and planes of cell divisions, coupled with regulated and coordinated cellular expansion