Abstract

The shoot apical meristem (SAM) is a dome-shaped tissue that contains the stem cells for generating the aerial parts of the plant. We have found the maintenance of the stem cell pool to require members of an ancient family of cell wall enzymes that make a polymer that forms the major load bearing unit of the SAM cell wall. Mutant combinations have small misshapen meristems that terminate after forming no more than 2-3 flowers. The boundary region between differentiated and undifferentiated tissue is poorly formed and increasing stress within the meristematic tissue results in failure of the cell wall composite. Together with linkage analysis of the cell walls of the SAM central zone, it appears the wall is not the typical primary wall that forms in the differentiated tissue. Our hypothesis is that the SAM makes a cell wall that is better able to respond to signals and positional cues prior to organogenesis and further work in this area will be presented.