title: Diversification of gene function: homologs of the floral regulator FLO/LFY control the first zygotic cell division in the moss Physcomitrella patens.
abstract: After fertilization, the zygote undergoes dynamic changes in chromosomal and cytoplasmic organization, and begins the cell cycles that eventually lead to formation of the multicellular embryo. Specific transcription factors that initiate this cascade of events in land plants have not been identified. We have identified two FLO/LFY genes, PpLFY1 and PpLFY2, that regulate the first cell division after formation of the zygote in the moss Physcomitrella patens. The deduced amino acid sequences of the two PpLFY genes are 94.8% identical to each other and show similar expression patterns. While fertilization occurred in the PpLFY disruptants, the development of double disruptant zygotes was arrested at the single-cell stage. When the double disruptants, as the female parent, were crossed with the wild type, as the male parent, normal sporophytes were formed, supporting the notion that the PpLFY genes function after fertilization to regulate the first mitotic cell division in zygotes. The rare sporophytes that formed on the PpLFY double disruptants showed mostly normal organogenesis, but had abnormalities in the pattern of cell division, supporting a role of PpLFY genes in regulating cell division. The FLO/LFY genes in angiosperms are conserved master regulators of floral identity without any obvious effects on cell division. By contrast, our study suggests that FLO/LFY genes have functions throughout sporophyte development in the basal land plant lineages.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Tanahashi
authors.forename: Naomi
authors.initials: N
authors.lastname: Sumikawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kato
authors.forename: Mitsuyasu
authors.initials: M
authors.lastname: Hasebe
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D019068:Bryopsida / Q000196:embryology / Q000235:genetics* / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D020869:Gene Expression Profiling; D018014:Gene Transfer Techniques; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D015053:Zygote / Q000166:cytology / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C074747:LFY protein, Arabidopsis; D014157:Transcription Factors