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The Armadillo repeat gene ZAK IXIK promotes Arabidopsis early embryo and endosperm development through a distinctive gametophytic maternal effect.

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Ngo Quy A, Baroux Celia, Guthörl Daniela, Mozerov Peter, Collinge Margaret A, Sundaresan Venkatesan, Grossniklaus Ueli,
Project The Genetic and Molecular Basis of Gametogenesis and Maternal Effects in Arabidopsis
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Original article (peer-reviewed)

Journal The Plant cell
Volume (Issue) 24(10)
Page(s) 4026 - 43
Title of proceedings The Plant cell
DOI 10.1105/tpc.112.102384

Open Access

Type of Open Access Publisher (Gold Open Access)


The proper balance of parental genomic contributions to the fertilized embryo and endosperm is essential for their normal growth and development. The characterization of many gametophytic maternal effect (GME) mutants affecting seed development indicates that there are certain classes of genes with a predominant maternal contribution. We present a detailed analysis of the GME mutant zak ixik (zix), which displays delayed and arrested growth at the earliest stages of embryo and endosperm development. ZIX encodes an Armadillo repeat (Arm) protein highly conserved across eukaryotes. Expression studies revealed that ZIX manifests a GME through preferential maternal expression in the early embryo and endosperm. This parent-of-origin-dependent expression is regulated by neither the histone and DNA methylation nor the DNA demethylation pathways known to regulate some other GME mutants. The ZIX protein is localized in the cytoplasm and nucleus of cells in reproductive tissues and actively dividing root zones. The maternal ZIX allele is required for the maternal expression of miniseed3. Collectively, our results reveal a reproductive function of plant Arm proteins in promoting early seed growth, which is achieved through a distinct GME of ZIX that involves mechanisms for maternal allele-specific expression that are independent of the well-established pathways.