FASCIATA genes for chromatin assembly factor-1 in Arabidopsis maintain thecellular organization of apical meristems

Postembryonic development of plants depends on the activity of apical meris tems established during embryogenesis. The shoot apical meristem (SAM) and the root apical meristem (RAM) have similar but distinct cellular organizat ion. Arabidopsis FASCIATA1 (FAS1) and FAS2 genes maintain the cellular and functional organization of both SAM and RAM, and FAS gene products are subu nits of the Arabidopsis counterpart of chromatin assembly factor-1 (CAF-1). fas mutants are defective in maintenance of the expression states of WUSCH EL (WUS) in SAM and SCARECROW (SCR) in RAM. We suggest that CAF-1 plays a c ritical role in the organization of SAM and RAM during postembryonic develo pment by facilitating stable maintenance of gene expression states.