title: Transgene elimination in genetically modified dry bean and soybean lines.
abstract: Transgene elimination is a poorly studied phenomenon in plants. We made genetic and molecular studies of a transgenic dry bean line immune to bean golden mosaic geminivirus and a soybean line. In both lines, the transgenes were stable during the vegetative phase but were eliminated during meiosis. Due to its potential biotechnological value, this transgenic line was micropropagated by grafting and the vegetative copies were studied for more than two years. More than 300 plants of progeny were obtained during this period, demonstrating that the phenomenon of elimination was consistently repeated and offering an opportunity for detailed study of transgene elimination, including the characterization of the integration sites. Cloning and sequencing of the transgenic loci, reciprocal crosses to untransformed plants, genomic DNA blots, and GUS assays were performed in the transgenic lines. Based on the molecular and genetic characterization, possible mechanisms involved in transgene elimination include intrachromosomal recombination, genetic instability resulting from the tissue culture manipulations, and co-elimination of transgenes, triggered by a process of genome defense.
authors.affiliation: Embrapa Recursos Genéticos e Biotecnologia, Parque Estação Biológica, Final Av. W3 Norte, 70770-900 Brasília, DF, Brazil. romano@cenargen.embrapa.br
authors.forename: Eduardo
authors.initials: E
authors.lastname: Romano
authors.forename: Alexandre
authors.initials: A
authors.lastname: Soares
authors.forename: Karina
authors.initials: K
authors.lastname: Proite
authors.forename: Suzana
authors.initials: S
authors.lastname: Neiva
authors.forename: Maíra
authors.initials: M
authors.lastname: Grossi
authors.forename: Josias C
authors.initials: JC
authors.lastname: Faria
authors.forename: Elíbio L
authors.initials: EL
authors.lastname: Rech
authors.forename: Francisco J L
authors.initials: FJ
authors.lastname: Aragão
mesh_terms: D018744:DNA, Plant; D017353:Gene Deletion; D005822:Genetic Vectors / Q000235:genetics; D009029:Mosaic Viruses; D027805:Phaseolus / Q000235:genetics* / Q000821:virology; D030821:Plants, Genetically Modified / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013025:Glycine max / Q000235:genetics* / Q000821:virology; D019076:Transgenes / Q000235:genetics*
chemical_list: D018744:DNA, Plant