marker-assisted selection in wheat - ictsd

152Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishSummarySince the 1980s, the use of molecular markers has been suggested to improve the efficiencyof releasing resistant varieties, thus overcoming difficulties met with classical breeding. Fortomato, a high-density molecular map is available in which more than 40 resistance genesare localized. Markers linked to these genes can be used to speed up gene transfer and pyramiding.Suitable PCR markers targeting resistance genes were constructed directly on thesequences of resistance genes or on restriction fragment length polymorphisms (RFLPs)tightly linked to them, and used to select resistant genotypes in backcross schemes. In somecases, the BC 5 generation was reached, and genotypes that cumulated two homozygousresistant genes were also obtained. These results supported the feasibility of using markerassistedselection (MAS) in tomato and reinforcing the potential of this approach for othergenes, which is today also driven by the development of new techniques and increasingknowledge about the tomato genome.