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Development. 2014 Dec;141(23):4580-9. doi: 10.1242/dev.111229. Epub 2014 Nov 5.

The Arabidopsis Mediator CDK8 module genes CCT (MED12) and GCT (MED13) are global regulators of developmental phase transitions.

Author information

1
Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Unidad de Genómica Avanzada, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Irapuato, Guanajuato, 36821, Mexico Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA sgillmor@langebio.cinvestav.mx spoethig@sas.upenn.edu.
2
Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Unidad de Genómica Avanzada, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Irapuato, Guanajuato, 36821, Mexico.
3
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
4
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA sgillmor@langebio.cinvestav.mx spoethig@sas.upenn.edu.

Abstract

Temporal coordination of developmental programs is necessary for normal ontogeny, but the mechanism by which this is accomplished is still poorly understood. We have previously shown that two components of the Mediator CDK8 module encoded by CENTER CITY (CCT; Arabidopsis MED12) and GRAND CENTRAL (GCT; Arabidopsis MED13) are required for timing of pattern formation during embryogenesis. A morphological, molecular and genomic analysis of the post-embryonic phenotype of gct and cct mutants demonstrated that these genes also promote at least three subsequent developmental transitions: germination, vegetative phase change, and flowering. Genetic and molecular analyses indicate that GCT and CCT operate in parallel to gibberellic acid, a phytohormone known to regulate these same three transitions. We demonstrate that the delay in vegetative phase change in gct and cct is largely due to overexpression of miR156, and that the delay in flowering is due in part to upregulation of FLC. Thus, GCT and CCT coordinate vegetative and floral transitions by repressing the repressors miR156 and FLC. Our results suggest that MED12 and MED13 act as global regulators of developmental timing by fine-tuning the expression of temporal regulatory genes.

KEYWORDS:

Arabidopsis thaliana; FLC; MED12; MED13; Mediator; miR156

PMID:
25377553
PMCID:
PMC4302938
DOI:
10.1242/dev.111229
[Indexed for MEDLINE]
Free PMC Article

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