It's particularly interesting to use wheat's capacity to tolerate partial chromosome deletions to help reconcile recombinational and cytological maps. Almost all of the fertile female florets carried the extra monosome. Those few fertile female gametes which produced viable embryos and lacked the extra monosome produced plants which upon examination carried chromosomes suffering from deletions. These deletion stocks permit Cytogenetic Ladder Mapping, the easy identification of a chromosomal region to which a genetic marker maps. Map it to a chromosome using as few tests as possible.
Deletion mapping is generally impossible with diploids.
However, the wheat-barley chromosome addition lines permit rapid mapping of barley genetic markers to chromosomes. In the grasses, it's generally relatively easy to find interchromosomal translocations. This often results in chromosomes which are easy to identify by their morphology. If you know the chromosome to which a marker maps, and you have the skill and patience to physically isolate translocated chromosomes, you can do PCR to see whether your marker lies either above or below the translocation. It's tedious work, but Kunzel and Korzun did a remarkable job of it.