EBP1 regulates organ size through cell growth and proliferation in plants

• Published in: The EMBO journal 2006-10, Vol.25 (20), p.4909-4920
• Main Authors: Horváth, Beatrix M, Magyar, Zoltán, Zhang, Yuexing, Hamburger, Anne W, Bakó, László, Visser, Richard GF, Bachem, Christian WB, Bögre, László
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; arabidopsis; Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins/genetics/metabolism; Arabidopsis/cytology/genetics/growth & development; Cell Cycle - physiology; Cell division; cell growth; Cell Line; cell proliferation; Cellular biology; cycle regulation; differential gene-expression; division; EBP1; EMBO06; EMBO30; erbb-3 binding-protein; expansion; Flowers & plants; Gene expression; Gene Expression Regulation, Plant - physiology; Genes; Humans; Indoleacetic Acids - metabolism; leaf; Meristem - cytology; Meristem - genetics; Meristem - metabolism; Meristem/cytology/genetics/metabolism; organ growth; organogenesis; Plant growth; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Proteins/genetics/metabolism; Plants, Genetically Modified; potato-tuber development; Proteins; ribosome biogenesis; Sequence Homology, Amino Acid; Solanum tuberosum - cytology; Solanum tuberosum - genetics; Solanum tuberosum - growth & development; Solanum tuberosum/cytology/genetics/growth & development; transcription factor; Transgenic plants
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7601362

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.