This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 16/4/1035    most recent tpc.019059v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (16) Citing Articles via Google Scholar Google Scholar Articles by Collinge, M. A. Articles by Grossniklaus, U. Search for Related Content PubMed PubMed Citation Articles by Collinge, M. A. Articles by Grossniklaus, U. Agricola Articles by Collinge, M. A. Articles by Grossniklaus, U.

Genetic Interaction of an Origin Recognition Complex Subunit and the Polycomb Group Gene MEDEA during Seed Development

Institute of Plant Biology, University of Zürich, 8008 Zürich, Switzerland

¹ To whom correspondence should be addressed. E-mail collinge{at}botinst.unizh.ch; fax 41-16348204.

The eukaryotic origin recognition complex (ORC) is made up of six subunits and functions in nuclear DNA replication, chromatin structure, and gene silencing in both fungi and metazoans. We demonstrate that disruption of a plant ORC subunit homolog, AtORC2 of Arabidopsis (Arabidopsis thaliana), causes a zygotic lethal mutant phenotype (orc2). Seeds of orc2 abort early, typically producing embryos with up to eight cells. Nuclear division in the endosperm is arrested at an earlier developmental stage: only approximately four nuclei are detected in orc2 endosperm. The endosperm nuclei in orc2 are dramatically enlarged, a phenotype that is most similar to class B titan mutants, which include mutants in structural maintenance of chromosomes (SMC) cohesins. The highest levels of ORC2 gene expression were found in preglobular embryos, coinciding with the stage at which homozygous orc2 mutant seeds arrest. The homologs of the other five Arabidopsis ORC subunits are also expressed at this developmental stage. The orc2 mutant phenotype is partly suppressed by a mutation in the Polycomb group gene MEDEA. In double mutants between orc2 and medea (mea), orc2 homozygotes arrest later with a phenotype intermediate between those of mea and orc2 single mutants. Either alterations in chromatin structure or the release of cell cycle checkpoints by the mea mutation may allow more cell and nuclear divisions to occur in orc2 homozygous seeds.

This article has been cited by other articles:

				M. de la Paz Sanchez and C. Gutierrez From the Cover: Arabidopsis ORC1 is a PHD-containing H3K4me3 effector that regulates transcription PNAS, February 10, 2009; 106(6): 2065 - 2070. [Abstract] [Full Text] [PDF]

				C. Baroux, D. Autran, C.S. Gillmor, D. Grimanelli, and U. Grossniklaus The Maternal to Zygotic Transition in Animals and Plants Cold Spring Harb Symp Quant Biol, February 9, 2009; (2009) sqb.2008.73.053v1. [Abstract] [PDF]

				R. W. Shultz, V. M. Tatineni, L. Hanley-Bowdoin, and W. F. Thompson Genome-Wide Analysis of the Core DNA Replication Machinery in the Higher Plants Arabidopsis and Rice Plant Physiology, August 1, 2007; 144(4): 1697 - 1714. [Abstract] [Full Text] [PDF]

				P. D. Jenik, R. E.J. Jurkuta, and M. K. Barton Interactions between the Cell Cycle and Embryonic Patterning in Arabidopsis Uncovered by a Mutation in DNA Polymerase {varepsilon} PLANT CELL, December 1, 2005; 17(12): 3362 - 3377. [Abstract] [Full Text] [PDF]

				S. Diaz-Trivino, M. del Mar Castellano, M. de la Paz Sanchez, E. Ramirez-Parra, B. Desvoyes, and C. Gutierrez The genes encoding Arabidopsis ORC subunits are E2F targets and the two ORC1 genes are differently expressed in proliferating and endoreplicating cells Nucleic Acids Res., September 22, 2005; 33(17): 5404 - 5414. [Abstract] [Full Text] [PDF]