title: Epigenetic interactions between Arabidopsis transgenes: characterization in light of transgene integration sites.
abstract: The stochastic variability of expression that is a characteristic of eukaryotic nuclear transgenes is often attributed to epigenetic mechanisms that are triggered by repetitive transgene locus structures and influenced by chromosomal position effects. In order to address the contribution of chromosomal position effects in the context of a fully sequenced genome, a novel set of transgene loci was established in the compact genome of Arabidopsis thaliana. Transgenes expressing GFP-tagged or GUS-tagged fusion proteins of Arabidopsis COP1 collectively displayed three types of gene silencing, which are distinguished by their developmental timing, gene dosage dependence, (post)transcriptional control, and extent of endogene co-suppression. Subsequently, the heritability of epistatic interactions between allelic and non-allelic transgene loci was investigated in light of both intrinsic transgene features, in particular T-DNA copy number per locus, and chromosomal insertion sites. The notion that chromosomal flanking sequences underlie the ability of transgenes to function as masters or targets of epigenetically heritable trans-silencing interactions was generally not favored by our data. Moreover, among single T-DNA loci at different chromosomal locations the great majority showed homozygosity-dependent posttranscriptional silencing. However, spontaneous silencing (in cis) may be promoted by a pericentromeric location. Instead, intrinsic transgene features correlated with all major aspects of silencing behavior tested.
authors.affiliation: Department of Botany, University of Tennessee, Knoxville, TN 37996-1100, USA.
authors.forename: Huaxia
authors.initials: H
authors.lastname: Qin
authors.forename: Yunzhou
authors.initials: Y
authors.lastname: Dong
authors.forename: Albrecht G
authors.initials: AG
authors.lastname: von Arnim
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D001665:Binding Sites / Q000187:drug effects; D004269:DNA, Bacterial / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional / Q000235:genetics; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013997:Time Factors; D019076:Transgenes / Q000235:genetics*; D044767:Ubiquitin-Protein Ligases
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D018744:DNA, Plant; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; C036483:T-DNA; D049452:Green Fluorescent Proteins; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D005966:Glucuronidase