Introgression of wheat DNA markers from A, B and D genomes in early generation progeny of <i>Aegilops cylindrica</i> Host × <i>Triticum aestivum</i> L. hybrids

Introgression from allohexaploid wheat (<i>Triticum aestivum</i> L., AABBDD) to allotetraploid jointed goatgrass (<i>Aegilops cylindrica</i> Host, CCDD) can take place in areas where the two species grow in sympatry and hybridize. Wheat and <i>Ae. cylindrica</i> share the D genome, issued from the common diploid ancestor <i>Aegilops tauschii</i> Coss. It has been proposed that the A and B genome of bread wheat are secure places to insert transgenes to avoid their introgression into <i>Ae. cylindrica</i> because during meiosis in pentaploid hybrids, A and B genome chromosomes form univalents and tend to be eliminated whereas recombination takes place only in D genome chromosomes. Wheat random amplified polymorphic DNA (RAPD) fragments, detected in intergeneric hybrids and introgressed to the first backcross generation with <i>Ae. cylindrica</i> as the recurrent parent and having a euploid <i>Ae. cylindrica</i> chromosome number or one supernumerary chromosome, were assigned to wheat chromosomes using Chinese Spring nulli-tetrasomic wheat lines. Introgressed fragments were not limited to the D genome of wheat, but specific fragments of A and B genomes were also present in the BC1. Their presence indicates that DNA from any of the wheat genomes can introgress into <i>Ae. cylindrica</i>. Successfully located RAPD fragments were then converted into highly specific and easy-to-use sequence characterised amplified regions (SCARs) through sequencing and primer design. Subsequently these markers were used to characterise introgression of wheat DNA into a BC1S1 family. Implications for risk assessment of genetically modified wheat are discussed.