title: Active DNA demethylation in plant companion cells reinforces transposon methylation in gametes.
abstract: The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation before fertilization, but the targeting preferences, mechanism, and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell and preferentially targets small, AT-rich, and nucleosome-depleted euchromatic transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA-directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes and likely contributes to stable silencing of transposable elements across generations.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Ibarra
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Feng
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, 1030 Vienna, Austria.
authors.forename: Vera K
authors.initials: VK
authors.lastname: Schoft
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Tzung-Fu
authors.initials: TF
authors.lastname: Hsieh
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Rie
authors.initials: R
authors.lastname: Uzawa
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Rodrigues
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Assaf
authors.initials: A
authors.lastname: Zemach
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, 1030 Vienna, Austria.
authors.forename: Nina
authors.initials: N
authors.lastname: Chumak
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, 1030 Vienna, Austria.
authors.forename: Adriana
authors.initials: A
authors.lastname: Machlicova
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Nishimura
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Denisse
authors.initials: D
authors.lastname: Rojas
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Fischer
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, 1030 Vienna, Austria.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Tamaru
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Zilberman
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004251:DNA Transposable Elements / Q000235:genetics*; D018744:DNA, Plant / Q000378:metabolism; D056625:Endosperm / Q000166:cytology / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D055993:Germ Cells, Plant / Q000378:metabolism*; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004251:DNA Transposable Elements; D018744:DNA, Plant; D018749:RNA, Plant; D015534:Trans-Activators; C463261:DEMETER protein, Arabidopsis; D009699:N-Glycosyl Hydrolases