A bistable circuit involving SCARECROW-RETINOBLASTOMA integrates cues to inform asymmetric stem cell division

Alfredo Cruz-Ramírez, Sara Díaz-Triviño, Ikram Blilou, Verônica A Grieneisen, Rosangela Sozzani, Christos Zamioudis, Pál Miskolczi, Jeroen Nieuwland, René Benjamins, Pankaj Dhonukshe, Juan Caballero-Pérez, Beatrix Horvath, Yuchen Long, Ari Pekka Mähönen, Hongtao Zhang, Jian Xu, James A H Murray, Philip N Benfey, Laszlo Bako, Athanasius F M MaréeBen Scheres

Research output: Contribution to journalArticlepeer-review


In plants, where cells cannot migrate, asymmetric cell divisions (ACDs) must be confined to the appropriate spatial context. We investigate tissue-generating asymmetric divisions in a stem cell daughter within the Arabidopsis root. Spatial restriction of these divisions requires physical binding of the stem cell regulator SCARECROW (SCR) by the RETINOBLASTOMA-RELATED (RBR) protein. In the stem cell niche, SCR activity is counteracted by phosphorylation of RBR through a cyclinD6;1-CDK complex. This cyclin is itself under transcriptional control of SCR and its partner SHORT ROOT (SHR), creating a robust bistable circuit with either high or low SHR-SCR complex activity. Auxin biases this circuit by promoting CYCD6;1 transcription. Mathematical modeling shows that ACDs are only switched on after integration of radial and longitudinal information, determined by SHR and auxin distribution, respectively. Coupling of cell-cycle progression to protein degradation resets the circuit, resulting in a "flip flop" that constrains asymmetric cell division to the stem cell region.

Original languageEnglish
Pages (from-to)1002-15
Number of pages14
Issue number5
Publication statusPublished - 31 Aug 2012


  • Amino Acid Sequence
  • Arabidopsis
  • Arabidopsis Proteins
  • Asymmetric Cell Division
  • Cyclin D
  • Cyclin-Dependent Kinases
  • Indoleacetic Acids
  • Mesophyll Cells
  • Molecular Sequence Data
  • Phosphorylation
  • Plant Roots
  • Sequence Alignment


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