title: Arabidopsis TEBICHI, with helicase and DNA polymerase domains, is required for regulated cell division and differentiation in meristems.
abstract: In plant meristems, each cell divides and differentiates in a spatially and temporally regulated manner, and continuous organogenesis occurs using cells derived from the meristem. We report the identification of the Arabidopsis thaliana TEBICHI (TEB) gene, which is required for regulated cell division and differentiation in meristems. The teb mutants show morphological defects, such as short roots, serrated leaves, and fasciation, as well as defective patterns of cell division and differentiation in the meristem. The TEB gene encodes a homolog of Drosophila MUS308 and mammalian DNA polymerase theta, which prevent spontaneous or DNA damage-induced production of DNA double strand breaks. As expected from the function of animal homologs, teb mutants show constitutively activated DNA damage responses. Unlike other fasciation mutants with activated DNA damage responses, however, teb mutants do not activate transcriptionally silenced genes. teb shows an accumulation of cells expressing cyclinB1;1:GUS in meristems, suggesting that constitutively activated DNA damage responses in teb lead to a defect in G2/M cell cycle progression. Furthermore, other fasciation mutants, such as fasciata2 and tonsoku/mgoun3/brushy1, also show an accumulation of cells expressing cyclinB1;1:GUS in meristems. These results suggest that cell cycle progression at G2/M is important for the regulation of the pattern of cell division and of differentiation during plant development.
authors.affiliation: Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan. i042002d@mbox.nagoya-u.ac.jp
authors.forename: Soichi
authors.initials: S
authors.lastname: Inagaki
authors.forename: Takamasa
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masa-aki
authors.initials: MA
authors.lastname: Ohto
authors.forename: Hiroko
authors.initials: H
authors.lastname: Urawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Horiuchi
authors.forename: Kenzo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Atsushi
authors.initials: A
authors.lastname: Morikami
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D004265:DNA Helicases / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D018519:Meristem / Q000166:cytology*; D008969:Molecular Sequence Data
chemical_list: D029681:Arabidopsis Proteins; C511743:TEBICHI protein, Arabidopsis; D004259:DNA-Directed DNA Polymerase; D004265:DNA Helicases