title: Epigenetic repression of male gametophyte-specific genes in the Arabidopsis sporophyte.
abstract: Tissue formation, the identity of cells, and the functions they fulfill, are results of gene regulation. The male gametophyte of plants, pollen, is outstanding in this respect as several hundred genes expressed in pollen are not expressed in the sporophyte. How pollen-specific genes are down-regulated in the sporophyte has yet to be established. In this study, we have performed a bioinformatics analysis of publicly available genome-wide epigenetics data of several sporophytic tissues. By combining this analysis with DNase I footprinting data, we assessed means by which the repression of pollen-specific genes in the Arabidopsis sporophyte is conferred. Our findings show that, in seedlings, the majority of pollen-specific genes are associated with histone-3 marked by mono- or trimethylation of Lys-27 (H3K27me1/H3K27me3), both of which are repressive markers for gene expression in the sporophyte. Analysis of DNase footprint profiles of pollen-specific genes in the sporophyte displayed closed chromatin proximal to the start codon. We describe a model of two-staged gene regulation in which a lack of nucleosome-free regions in promoters and histone modifications in open reading frames repress pollen-specific genes in the sporophyte.
authors.affiliation: Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark. hoffmann@life.ku.dk
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hoffmann
authors.forename: Michael G
authors.initials: MG
authors.lastname: Palmgren
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology*; D001665:Binding Sites; D019175:DNA Methylation; D057225:Data Mining; D030541:Databases, Genetic; D004171:Diploidy; D063185:Epigenetic Repression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D006657:Histones / Q000235:genetics; D009928:Organ Specificity; D011058:Pollen / Q000235:genetics* / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D006657:Histones; D014157:Transcription Factors
keywords: DNase I footprinting; bioinformatics.; epigenetics; gene repression; male gametophyte; transcription factors