Figure 4. Coordinated replication in root meristem cell files is dependent on a SET-domain gene. Wild type (Col-0) and SET-domain gene mutant root meristems stained 1 h with the thymidine analog EdU to visualize DNA-replicating nuclei (in green and pink, respectively). The wild type image exemplifies a coordinated pattern, in this case along an endodermal (En) cell file, with a replicating singlet (1) nearest the quiescent center (QC), followed by a duplet (2), quartet (4) and octet (8) of co-replicating daughter, granddaughter and great-granddaughter cells. This coordinated replication pattern is distorted in the SET-domain gene mutant. C, cortex; Ep, epidermis. Courtesy of R. B. Aalen (Oslo, Norway); images by Robert Kumpf.