A genetic framework for the control of cell division and differentiation in the root meristem.
Plant growth and development are sustained by meristems. Meristem activity is controlled by auxin and cytokinin, two hormones whose interactions in determining a specific developmental output are still poorly understood. By means of a comprehensive genetic and molecular analysis in Arabidopsis, we show that a primary cytokinin-response transcription factor, ARR1, activates the gene SHY2/IAA3 (SHY2), a repressor of auxin signaling that negatively regulates the PIN auxin transport facilitator genes: thereby, cytokinin causes auxin redistribution, prompting cell differentiation. Conversely, auxin mediates degradation of the SHY2 protein, sustaining PIN activities and cell division. Thus, the cell differentiation and division balance necessary for controlling root meristem size and root growth is the result of the interaction between cytokinin and auxin through a simple regulatory circuit converging on the SHY2 gene.
Dello Ioio
Raffaele
R
Dipartimento di Genetica e Biologia Molecolare, Laboratorio di Genomica e Proteomica Funzionale dei Sistemi Modello (FGPL), Università La Sapienza - Piazzale Aldo Moro 5, 00185 Rome, Italy.
Nakamura
Kinu
K
Moubayidin
Laila
L
Perilli
Serena
S
Taniguchi
Masatoshi
M
Morita
Miyo T
MT
Aoyama
Takashi
T
Costantino
Paolo
P
Sabatini
Sabrina
S
D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D003583:Cytokinins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000166:cytology* / Q000254:growth & development; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology* / Q000254:growth & development; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
C117138:ARR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D009687:Nuclear Proteins; C116363:PIN1 protein, Arabidopsis; C449300:PIN3 protein, Arabidopsis; C479554:PIN7 protein, Arabidopsis; C117994:SHY2 protein, Arabidopsis; D014157:Transcription Factors