title: Genomic imprinting in the Arabidopsis embryo is partly regulated by PRC2.
abstract: Genomic imprinting results in monoallelic gene expression in a parent-of-origin-dependent manner and is regulated by the differential epigenetic marking of the parental alleles. In plants, genomic imprinting has been primarily described for genes expressed in the endosperm, a tissue nourishing the developing embryo that does not contribute to the next generation. In Arabidopsis, the genes MEDEA (MEA) and PHERES1 (PHE1), which are imprinted in the endosperm, are also expressed in the embryo; whether their embryonic expression is regulated by imprinting or not, however, remains controversial. In contrast, the maternally expressed in embryo 1 (mee1) gene of maize is clearly imprinted in the embryo. We identified several imprinted candidate genes in an allele-specific transcriptome of hybrid Arabidopsis embryos and confirmed parent-of-origin-dependent, monoallelic expression for eleven maternally expressed genes (MEGs) and one paternally expressed gene (PEG) in the embryo, using allele-specific expression analyses and reporter gene assays. Genetic studies indicate that the Polycomb Repressive Complex 2 (PRC2) but not the DNA METHYLTRANSFERASE1 (MET1) is involved in regulating imprinted expression in the embryo. In the seedling, all embryonic MEGs and the PEG are expressed from both parents, suggesting that the imprint is erased during late embryogenesis or early vegetative development. Our finding that several genes are regulated by genomic imprinting in the Arabidopsis embryo clearly demonstrates that this epigenetic phenomenon is not a unique feature of the endosperm in both monocots and dicots.
authors: Institute of Plant Biology & Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland.
authors: Michael T
authors: MT
authors: Raissig
authors: Marian
authors: M
authors: Bemer
authors: Célia
authors: C
authors: Baroux
authors: Ueli
authors: U
authors: Grossniklaus
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000235:genetics*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D056625:Endosperm / Q000235:genetics / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018392:Genomic Imprinting; D026161:MADS Domain Proteins / Q000096:biosynthesis; D019684:Magnoliopsida / Q000235:genetics; D063151:Polycomb Repressive Complex 2; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics*; D012639:Seeds / Q000235:genetics* / Q000254:growth & development; D003313:Zea mays / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D026161:MADS Domain Proteins; C111712:MEA protein, Arabidopsis; C475745:PHERES1 protein, Arabidopsis; C574170:PRC2 protein, Arabidopsis; D012097:Repressor Proteins; C499608:MET1 protein, Arabidopsis; D004248:DNA (Cytosine-5-)-Methyltransferases; D063151:Polycomb Repressive Complex 2