IngentaConnect Genetic analysis of two Arabidopsis DNA polymerase epsilon subuni...

Authors: Ronceret, Arnaud¹; Guilleminot, Jocelyne¹; Lincker, Frédéric²; Gadea-Vacas, Jose³; Delorme, Valérie¹; Bechtold, Nicole; Pelletier, Georges⁴; Delseny, Michel¹; Chabouté, Marie-Edith²; Devic, Martine

Source: The Plant Journal, Volume 44, Number 2, October 2005 , pp. 223-236(14)

Publisher: Blackwell Publishing

Abstract:

Summary

Accurate DNA replication is one of the most important events in the life of a cell. To perform this task, the cell utilizes several DNA polymerase complexes. We investigated the role of DNA polymerase during gametophyte and seed development using forward and reverse genetic approaches. In Arabidopsis, the catalytic subunit of this complex is encoded by two genes, AtPOL2a and AtPOL2b, whereas the second largest regulatory subunit AtDPB2 is present as a unique complete copy. Disruption of AtPOL2a or AtDPB2 resulted in a sporophytic embryo-defective phenotype, whilst mutations in AtPOL2b produced no visible effects. Loss of AtDPB2 function resulted in a severe reduction in nuclear divisions, both in the embryo and in the endosperm. Mutations in AtPOL2a allowed several rounds of mitosis to proceed, often with aberrant planes of division. Moreover, AtDPB2 was not expressed during development of the female gametophyte, which requires three post-meiotic nuclear divisions. Since a consensus binding site for E2F transcription factors was identified in the promoter region of both genes, the promoter–reporter fusion technique was used to show that luciferase activity was increased at specific phases of the cell cycle in synchronized tobacco BY-2 cells. Our results support the idea that fertilization may utilize the mechanisms of cell cycle transcriptional regulation of genes to reactivate the divisions of the oosphere and central cell.

Keywords: DNA polymerase epsilon; embryogenesis; cell cycle; fertilization

Document Type: Research article

DOI: 10.1111/j.1365-313X.2005.02521.x

Affiliations: 1: Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD-Université 5096, 52 Avenue Paul Alduy, 66860 Perpignan-cedex, France, 2: Institut de Biologie Moléculaire des Plantes du CNRS, 12 rue du Général Zimmer, 67084 Strasbourg-cedex, France, 3: Genomics Laboratory, Institute for Molecular and Cellular Biology of Plants, UPV-CSIC Av. Naranjos s/n, 46022 Valencia, Spain, and 4: Station de Génétique et Amélioration des Plantes, INRA, Route de Saint-Cyr, 78026 Versailles-cedex, France

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Genetic analysis of two Arabidopsis DNA polymerase epsilon subunits during early embryogenesis