title: Retinoblastoma protein regulates cell proliferation, differentiation, and endoreduplication in plants.
abstract: Retinoblastoma protein (Rb) plays a key role in cell cycle control, cell differentiation, and apoptosis in animals. In this study, we used virus-induced gene silencing (VIGS) to investigate the cellular functions of Rb in higher plants. VIGS of NbRBR1, which encodes the Nicotiana benthamiana Rb homolog, resulted in growth retardation and abnormal organ development. At the cellular level, Rb suppression caused prolonged cell proliferation in tissues that are normally differentiated, which indicates that Rb is a negative regulator of plant cell division. Furthermore, differentiation of the epidermal pavement cells and trichomes was partially retarded, and stomatal clusters formed in the epidermis, likely due to uncontrolled cell division of stomata precursor cells. Rb suppression also caused extra DNA replication in endoreduplicating leaf cells, suggesting a role of Rb in the endocycle. These Rb phenotypes were accompanied by stimulated transcription of E2F and E2F-regulated S-phase genes. Thus, disruption of Rb function in plants leads to ectopic cell division in major organs that correlates with a delay in cell differentiation as well as increased endoreduplication, which indicates that Rb coordinates these processes in plant organ development.
authors.affiliation: Department of Biology, Yonsei University 134, Seoul 120-749, Korea.
authors.forename: Jong-A
authors.initials: JA
authors.lastname: Park
authors.forename: Joon-Woo
authors.initials: JW
authors.lastname: Ahn
authors.forename: Yu-Kyung
authors.initials: YK
authors.lastname: Kim
authors.forename: Su Jung
authors.initials: SJ
authors.lastname: Kim
authors.forename: Ju-Kon
authors.initials: JK
authors.lastname: Kim
authors.forename: Woo Taek
authors.initials: WT
authors.lastname: Kim
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Pai
mesh_terms: D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D020868:Gene Silencing; D018515:Plant Leaves / Q000502:physiology / Q000648:ultrastructure; D010940:Plant Proteins / Q000502:physiology*; D018547:Plant Stems / Q000502:physiology; D030821:Plants, Genetically Modified; D016160:Retinoblastoma Protein / Q000502:physiology*; D014026:Nicotiana / Q000166:cytology / Q000502:physiology*; D014158:Transcription, Genetic; D015854:Up-Regulation
chemical_list: D010940:Plant Proteins; D016160:Retinoblastoma Protein