title: A role for CHROMOMETHYLASE3 in mediating transposon and euchromatin silencing during egg cell reprogramming in Arabidopsis.
abstract: During embryogenesis there is a major switch from dependence upon maternally-deposited products to reliance on products of the zygotic genome. In animals, this so-called maternal-to-zygotic transition occurs following a period of transcriptional quiescence. Recently, we have shown that the early embryo in Arabidopsis is also quiescent, a state inherited from the female gamete and linked to specific patterns of H3K9 dimethylation and TERMINAL FLOWER2 (TFL2) localization. We also demonstrated that CHROMOMETHYLASE 3 (CMT3) is required for H3K9 dimethylation in the egg cell and for normal embryogenesis during the first few divisions of the zygote. Subsequent analysis of CMT3 mutants points to a key role in egg cell reprogramming by controlling silencing in both transposon and euchromatic regions. A speculative model of the CMT3-induced egg cell silencing is presented here, based on these results and current data from the literature suggesting the potential involvement of small RNAs targeted to the egg cell, a process conceptually similar to the division of labor described in the male gametophyte for which we show that H3K9 modifications and TFL2 localization are reminiscent of the female gametophyte.
authors.affiliation: Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096 IRD-CNRS-Université de Perpignan, Montpellier, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Pillot
authors.forename: Daphné
authors.initials: D
authors.lastname: Autran
authors.forename: Olivier
authors.initials: O
authors.lastname: Leblanc
authors.forename: Daniel
authors.initials: D
authors.lastname: Grimanelli
mesh_terms: D000107:Acetylation; D017360:Arabidopsis / Q000166:cytology / Q000196:embryology / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D065150:Cellular Reprogramming; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D019175:DNA Methylation; D004251:DNA Transposable Elements / Q000235:genetics*; D015257:DNA-Cytosine Methylases / Q000378:metabolism*; D022041:Euchromatin / Q000235:genetics*; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D008954:Models, Biological; D056771:Ovule / Q000166:cytology; D010063:Ovum / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D021381:Protein Transport; D018749:RNA, Plant / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D004251:DNA Transposable Elements; D015257:DNA-Cytosine Methylases; D022041:Euchromatin; D006657:Histones; D018749:RNA, Plant; C477788:At5g17690 protein, Arabidopsis; C429766:CMT3 protein, Arabidopsis