title: The boundary of the meristematic and elongation zones in roots: endoreduplication precedes rapid cell expansion.
abstract: Plant roots consist of a meristematic zone of mitotic cells and an elongation zone of rapidly expanding cells, in which DNA replication often occurs without cell division, a process known as endoreduplication. The duration of the cell cycle and DNA replication, as measured by 5-ethynyl-2'-deoxy-uridine (EdU) incorporation, differed between the two regions (17 h in the meristematic zone, 30 h in the elongation zone). Two distinct subnuclear patterns of EdU signals, whole and speckled, marked nuclei undergoing DNA replication at early and late S phase, respectively. The boundary region between the meristematic and elongation zones was analysed by a combination of DNA replication imaging and optical estimation of the amount of DNA in each nucleus (C-value). We found a boundary cell with 4C nuclei exhibiting the whole pattern of EdU signals. Analyses of cells in the boundary region revealed that endoreduplication precedes rapid cell elongation in roots.
authors.affiliation: Department of Applied Biological Science Faculty of Science and Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Kohma
authors.initials: K
authors.lastname: Hayashi
authors.forename: Junko
authors.initials: J
authors.lastname: Hasegawa
authors.forename: Sachihiro
authors.initials: S
authors.lastname: Matsunaga
mesh_terms: D017360:Arabidopsis / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D004261:DNA Replication; D018744:DNA, Plant; D062951:Endoreduplication / Q000502:physiology*; D059828:Plant Cells / Q000502:physiology*; D018517:Plant Roots / Q000166:cytology*
chemical_list: D018744:DNA, Plant