Comparison among available marker systems for cereal introgression breeding: A practical perspective

There is an increasing amount of public sequence information for the main cultivated cereals, such as wheat and barley. It is not foreseeable that comparable efforts or resources could be devoted to related wild species. However, wild species are interesting sources of genetic variation through introgression breeding. Comparative genomics can be a helpful approach to make use of the available genomic resources. In this context, the potential of the wild barley species Hordeum chilense has been explored in recent years. It exhibits great levels of polymorphism and high crossability with different cereal genera. In addition, interesting biotic and abiotic stress resistance genes, and important quality traits like carotene content and seed storage protein variability shown in the species are also expressed in wheat backgrounds, and are the basis of a breeding program. Different approaches have been undertaken for tagging H. chilense genomic regions in a wheat background. The search for the most suitable DNA marker system started with the development of RAPD and SCAR markers due to a lack of sequence information from the wild species. Transferability of markers from wheat and barley (like STSs or SSRs) have also been useful approximations. More recently, SNP development is being accomplished for the species. In this work, the situation and prospects with the available molecular tools are considered from a practical point of view.Supported by projects AGL2003-0720 and HA2002-0076 from DGI, Spain.Peer reviewe