title: Cell type-specific role of the retinoblastoma/E2F pathway during Arabidopsis leaf development.
abstract: Organogenesis in plants is almost entirely a postembryonic process. This unique feature implies a strict coupling of cell proliferation and differentiation, including cell division, arrest, cell cycle reactivation, endoreplication, and differentiation. The plant retinoblastoma-related (RBR) protein modulates the activity of E2F transcription factors to restrict cell proliferation. Arabidopsis contains a single RBR gene, and its loss of function precludes gamete formation and early development. To determine the relevance of the RBR/E2F pathway during organogenesis, outside its involvement in cell division, we have used an inducible system to inactivate RBR function and release E2F activity. Here, we have focused on leaves where cell proliferation and differentiation are temporally and developmentally regulated. Our results reveal that RBR restricts cell division early during leaf development when cell proliferation predominates, while it regulates endocycle occurrence at later stages. Moreover, shortly after leaving the cell cycle, most of leaf epidermal pavement cells retain the ability to reenter the cell cycle and proliferate, but maintain epidermal cell fate. On the contrary, mesophyll cells in the inner layers do not respond in this way to RBR loss of activity. We conclude that there exists a distinct response of different cells to RBR inactivation in terms of maintaining the balance between cell division and endoreplication during Arabidopsis (Arabidopsis thaliana) leaf development.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Desvoyes
authors.forename: Elena
authors.initials: E
authors.lastname: Ramirez-Parra
authors.forename: Qi
authors.initials: Q
authors.lastname: Xie
authors.forename: Nam-Hai
authors.initials: NH
authors.lastname: Chua
authors.forename: Crisanto
authors.initials: C
authors.lastname: Gutierrez
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism / Q000502:physiology*; D002454:Cell Differentiation; D002455:Cell Division / Q000502:physiology; D050684:E2F Transcription Factors / Q000378:metabolism*; D017791:Geminiviridae / Q000235:genetics; D018515:Plant Leaves / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000378:metabolism; D015398:Signal Transduction; D015854:Up-Regulation; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D050684:E2F Transcription Factors; C487568:RBR1 protein, Arabidopsis; D014764:Viral Proteins