Ioio, I D and Galinha, C and Fletcher, A G and Grigg, S P and Molnar, A and Willemsen, V and Scheres, B and Maini, P. K. and Tsiantis, M (2012) A PHABULOSA/cytokinin feedback loop controls root growth in arabidopsis. Current Biology, 22 (18). pp. 1699-1704.
The hormone cytokinin (CK) controls root length in Arabidopsis thaliana by defining where dividing cells, derived from stem cells of the root meristem, start to differentiate [ , , , ,  and ]. However, the regulatory inputs directing CK to promote differentiation remain poorly understood. Here, we show that the HD-ZIPIII transcription factor PHABULOSA (PHB) directly activates the CK biosynthesis gene ISOPENTENYL TRANSFERASE 7 (IPT7), thus promoting cell differentiation and regulating root length. We further demonstrate that CK feeds back to repress both PHB and microRNA165, a negative regulator of PHB. These interactions comprise an incoherent regulatory loop in which CK represses both its activator and a repressor of its activator. We propose that this regulatory circuit determines the balance of cell division and differentiation during root development and may provide robustness against CK fluctuations.
|Subjects:||A - C > Biology and other natural sciences|
|Research Groups:||Centre for Mathematical Biology|
|Deposited By:||Philip Maini|
|Deposited On:||27 Sep 2012 07:39|
|Last Modified:||27 Sep 2012 07:39|
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