A Genetic Framework for the Control of Cell Division and Differentiation in the Root Meristem
Raffaele Dello Ioio,1
Kinu Nakamura,2*
Laila Moubayidin,1*
Serena Perilli,1*
Masatoshi Taniguchi,2
Miyo T. Morita,3
Takashi Aoyama,2
Paolo Costantino,1
Sabrina Sabatini1
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.
2 Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
3 Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, 630-0101, Japan.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: sabrina.sabatini{at}uniroma1.it
