PROCEEDINGS Open Access Computational and experimental analyses of retrotransposon-associated minisatellite DNAs in the soybean genome

Background: Retrotransposons are mobile DNA elements that spread through genomes via the action of element-encoded reverse transcriptases. They are ubiquitous constituents of most eukaryotic genomes, especially those of higher plants. The pericentromeric regions of soybean (Glycine max) chromosomes contain>3,200 intact copies of the Gmr9/GmOgre retrotransposon. Between the 3 ’ end of the coding region and the long terminal repeat, this retrotransposon family contains a polymorphic minisatellite region composed of five distinct, interleaved minisatellite families. To better understand the possible role and origin of retrotransposon-associated minisatellites, a computational project to map and physically characterize all members of these families in the G. max genome, irrespective of their association with Gmr9, was undertaken. Methods: A computational pipeline was developed to map and analyze the organization and distribution of five Gmr9-associated minisatellites throughout the soybean genome. Polymerase chain reaction amplifications were used to experimentally assess the computational outputs. Results: A total of 63,841 copies of Gmr9-associated minisatellites were recovered from the assembled G. max genome. Ninety percent were associated with Gmr9, an additional 9 % with other annotated retrotransposons, and 1 % with uncharacterized repetitive DNAs. Monomers were tandemly interleaved and repeated up to 149 times pe