If QTL clusters contain tightly linked but distinct genes, as in these examples, the problem of linkage drag can be overcome by repeated crossing and careful marker-assisted selection to break the linkage between desirable and undesirable genes and to select the ideal combination of alleles.
In cases where a QTL has been fine-mapped or the causal gene(s) have been identified, the problem of linkage drag can be overcome by means of marker-assisted selection of recombinants between the target gene or QTL and nearby unfavorable genes (Fukuoka et al. 2009>).
A solution to the problem of linkage is found if some examiners examine on several different diets at different centres.
Moreover, GM technology circumvents the problem of linkage drag and can speed up the introgression of the R gene [ 18, 19].
Availability of abundant markers will facilitate association mapping, marker aided selection (MAS), and fine mapping of regions of interest for circumventing the problem of linkage drag during introgressions and for map based cloning.
The systematic analysis of polymorphisms across large parts of the human genome has begun to provide the first information on haplotypes and the problem of linkage disequilibrium across large genomic regions.
