Control of female gamete formation by a small RNA pathway in Arabidopsis

Olmedo-Monfil, V., Durán-Figueroa, N., Arteaga-Vázquez, M., Demesa-Arévalo, E., Autran, D., Grimanelli, D., Slotkin, R. K., Martienssen, R. A., Vielle-Calzada, J. P. (March 2010) Control of female gamete formation by a small RNA pathway in Arabidopsis. Nature, 464 (7288). pp. 628-632.

URL: http://www.ncbi.nlm.nih.gov/pubmed/20208518
DOI: 10.1038/nature08828

Abstract

In the ovules of most sexual flowering plants female gametogenesis is initiated from a single surviving gametic cell, the functional megaspore, formed after meiosis of the somatically derived megaspore mother cell (MMC). Because some mutants and certain sexual species exhibit more than one MMC, and many others are able to form gametes without meiosis (by apomixis), it has been suggested that somatic cells in the ovule are competent to respond to a local signal likely to have an important function in determination. Here we show that the Arabidopsis protein ARGONAUTE 9 (AGO9) controls female gamete formation by restricting the specification of gametophyte precursors in a dosage-dependent, non-cell-autonomous manner. Mutations in AGO9 lead to the differentiation of multiple gametic cells that are able to initiate gametogenesis. The AGO9 protein is not expressed in the gamete lineage; instead, it is expressed in cytoplasmic foci of somatic companion cells. Mutations in SUPPRESSOR OF GENE SILENCING 3 and RNA-DEPENDENT RNA POLYMERASE 6 exhibit an identical defect to ago9 mutants, indicating that the movement of small RNA (sRNAs) silencing out of somatic companion cells is necessary for controlling the specification of gametic cells. AGO9 preferentially interacts with 24-nucleotide sRNAs derived from transposable elements (TEs), and its activity is necessary to silence TEs in female gametes and their accessory cells. Our results show that AGO9-dependent sRNA silencing is crucial to specify cell fate in the Arabidopsis ovule, and that epigenetic reprogramming in companion cells is necessary for sRNA-dependent silencing in plant gametes.

Item Type: Paper
Uncontrolled Keywords: megaspore mother cell MMC Arabidopsis ARGONAUTE 9 AGO9 sRNA silencing plant gametes
Subjects: organism description > plant > Arabidopsis
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > argonaute proteins
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > sRNA
CSHL Authors:
Communities: CSHL labs > Martienssen lab
CSHL Cancer Center Shared Resources > Bioinformatics Service
CSHL Cancer Center Shared Resources > Microscopy Service
Depositing User: CSHL Librarian
Date: 25 March 2010
Date Deposited: 05 Oct 2011 14:27
Last Modified: 30 Dec 2014 17:07
Related URLs:
URI: http://repository.cshl.edu/id/eprint/15500

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