Retinoblastoma protein regulates cell proliferation, differentiation, and endoreduplication in plants.
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.
Park
Jong-A
JA
Department of Biology, Yonsei University 134, Seoul 120-749, Korea.
Ahn
Joon-Woo
JW
Kim
Yu-Kyung
YK
Kim
Su Jung
SJ
Kim
Ju-Kon
JK
Kim
Woo Taek
WT
Pai
Hyun-Sook
HS
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
D010940:Plant Proteins; D016160:Retinoblastoma Protein