Eduardo Romano, Alexandre Soares, Karina Proite, Suzana Neiva, Maíra Grossi, Josias C. Faria, Elíbio L. Rech, Francisco J.L. Aragão
Published May 18, 2005
Genet. Mol. Res. 4 (2): 177-184 (2005)

About the Authors
Eduardo Romano, Alexandre Soares, Karina Proite, Suzana Neiva, Maíra Grossi, Josias C. Faria, Elíbio L. Rech,  Francisco J.L. Aragão

Corresponding author
E. Romano
Email: romano@cenargen.embrapa.br

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 coelimination of transgenes, triggered by a process of genome defense.

Key words: Transgene locus structure, Gene integration, Biolistics, Transgene elimination.