title: Synergistic repression of the embryonic programme by SET DOMAIN GROUP 8 and EMBRYONIC FLOWER 2 in Arabidopsis seedlings.
abstract: The seed maturation programme occurs only during the late phase of embryo development, and repression of the maturation genes is pivotal for seedling development. However, mechanisms that repress the expression of this programme in vegetative tissues are not well understood. A genetic screen was performed for mutants that express maturation genes in leaves. Here, it is shown that mutations affecting SDG8 (SET DOMAIN GROUP 8), a putative histone methyltransferase, cause ectopic expression of a subset of maturation genes in leaves. Further, to investigate the relationship between SDG8 and the Polycomb Group (PcG) proteins, which are known to repress many developmentally important genes including seed maturation genes, double mutants were made and formation of somatic embryos was observed on mutant seedlings with mutations in both SDG8 and EMF2 (EMBRYONIC FLOWER 2). Analysis of histone methylation status at the chromatin sites of a number of maturation loci revealed a synergistic effect of emf2 and sdg8 on the deposition of the active histone mark which is the trimethylation of Lys4 on histone 3 (H3K4me3). This is consistent with high expression of these genes and formation of somatic embryos in the emf2 sdg8 double mutants. Interestingly, a double mutant of sdg8 and vrn2 (vernalization2), a paralogue of EMF2, grew and developed normally to maturity. These observations demonstrate a functional cooperative interplay between SDG8 and an EMF2-containing PcG complex in maintaining vegetative cell identity by repressing seed genes to promote seedling development. The work also indicates the functional specificities of PcG complexes in Arabidopsis.
authors.affiliation: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre, London, Ontario N5V 4T3, Canada.
authors.forename: Xurong
authors.initials: X
authors.lastname: Tang
authors.forename: Myung-Ho
authors.initials: MH
authors.lastname: Lim
authors.forename: Julie
authors.initials: J
authors.lastname: Pelletier
authors.forename: Mingjuan
authors.initials: M
authors.lastname: Tang
authors.forename: Vi
authors.initials: V
authors.lastname: Nguyen
authors.forename: Wilfred A
authors.initials: WA
authors.lastname: Keller
authors.forename: Edward W T
authors.initials: EW
authors.lastname: Tsang
authors.forename: Aiming
authors.initials: A
authors.lastname: Wang
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Rothstein
authors.forename: John J
authors.initials: JJ
authors.lastname: Harada
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Cui
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D004591:Electrophoresis, Polyacrylamide Gel; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C494299:EMF2 protein, Arabidopsis; D012097:Repressor Proteins; D011495:Histone-Lysine N-Methyltransferase; C556085:LAZ2 protein, Arabidopsis