Int. J. Dev. Biol. In Press
doi: 10.1387/ijdb.200098sg
© UPV/EHU Press

Identification of the maize Mediator CDK8 module, and transposon-mediated mutagenesis of ZmMed12a

Ana Laura Alonso-Nieves1, Tania Núñez-Ríos1, Julio A. Massange-Sánchez1,2, Kevin R. Ahern3, Daniel Lepe-Soltero1, Marcelina García-Aguilar1, Thomas P. Brutnell4, Ruairidh James Hay Sawers5,* and C. Stewart Gillmor1,*

1Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Unidad de Genómica Avanzada, Centro de Investigaciones y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Irapuato, Guanajuato, Mexico, 2<Unidad de Biotecnología Vegetal, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco A.C. (CIATEJ), Guadalajara, Mexico, 3Boyce Thompson Institute for Plant Research, Ithaca, New York, U.S.A.4Chinese Academy of Agricultural Sciences, Biotechnology Research Institute, Haidan District, Beijing, China and 5Department of Plant Science, Pennsylvania State University, State College, Pennsylvania, U.S.A.

ABSTRACT Background: Mediator is a conserved transcriptional co-activator that links transcription factors bound at enhancer elements to RNA Polymerase II. Mediator-RNA Polymerase II interactions can be sterically hindered by the Cyclin Dependent Kinase 8 (CDK8) module, a submodule of Mediator that acts to repress transcription in response to discrete cellular and environmental cues. The CDK8 module is conserved in all eukaryotes and consists of 4 proteins: CDK8, CYCLIN C (CYCC), MED12, and MED13. Methods: In this study, we have characterized the CDK8 module of Mediator in maize using genomic, molecular and functional resources. Results: The maize genome contains single copy genes for Cdk8, CycC, and Med13, and two genes for Med12. Analysis of expression data for the CDK8 module demonstrated that all five genes are broadly expressed in maize tissues, and change their expression in response to phosphate and nitrogen limitation. We performed Dissociation (Ds) insertional mutagenesis, recovering two independent insertions in the ZmMed12a gene, one of which produces a truncated transcript. Conclusions: Our molecular identification of the maize CDK8 module, assays of CDK8 module expression under nutrient limitation, and characterization of transposon insertions in ZmMed12a establish the basis for molecular and functional studies of the role of these important transcriptional regulators in development and nutrient homeostasis in Zea mays.

Keywords:

Zea mays, Mediator, Cdk8, Med12, Med13, CycC

*Corresponding author e-mail: rjs6686@psu.edu ; stewart.gillmor@cinvestav.mx