title: EBP1 regulates organ size through cell growth and proliferation in plants.
abstract: Plant organ size shows remarkable uniformity within species indicating strong endogenous control. We have identified a plant growth regulatory gene, functionally and structurally homologous to human EBP1. Plant EBP1 levels are tightly regulated; gene expression is highest in developing organs and correlates with genes involved in ribosome biogenesis and function. EBP1 protein is stabilised by auxin. Elevating or decreasing EBP1 levels in transgenic plants results in a dose-dependent increase or reduction in organ growth, respectively. During early stages of organ development, EBP1 promotes cell proliferation, influences cell-size threshold for division and shortens the period of meristematic activity. In postmitotic cells, it enhances cell expansion. EBP1 is required for expression of cell cycle genes; CyclinD3;1, ribonucleotide reductase 2 and the cyclin-dependent kinase B1;1. The regulation of these genes by EBP1 is dose and auxin dependent and might rely on the effect of EBP1 to reduce RBR1 protein level. We argue that EBP1 is a conserved, dose-dependent regulator of cell growth that is connected to meristematic competence and cell proliferation via regulation of RBR1 level.
authors.affiliation: Laboratory of Plant Breeding, Department of Plant Sciences, Graduate School of Experimental Plant Sciences, Wageningen University and Research Centre, Wageningen, The Netherlands. Beatrix.Horvath@WUR.nl
authors.forename: Beatrix M
authors.initials: BM
authors.lastname: Horváth
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Magyar
authors.forename: Yuexing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Anne W
authors.initials: AW
authors.lastname: Hamburger
authors.forename: László
authors.initials: L
authors.lastname: Bakó
authors.forename: Richard G F
authors.initials: RG
authors.lastname: Visser
authors.forename: Christian W B
authors.initials: CW
authors.lastname: Bachem
authors.forename: László
authors.initials: L
authors.lastname: Bögre
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology*; D002460:Cell Line; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D006801:Humans; D007210:Indoleacetic Acids / Q000378:metabolism; D018519:Meristem / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000166:cytology / Q000235:genetics / Q000254:growth & development*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010940:Plant Proteins; C487568:RBR1 protein, Arabidopsis