Polymorphic DNA bands were identified between a near iso-isogenic line
of wheat carrying both stem (Sr39) and leaf (Lr35) rust resistance
genes and the recurrent line Thatcher (Tc) which lacks these genes.
Both resistance genes are located on a translocated chromosomal segment
derived from Aegilops speltoides and thus are genetically linked. The
primers used to generate polymorphic bands were 3'-anchored
inter-simple sequence repeat primers which identified genomic
microsatellites with a repeated motif of 3 nucleotides in length. The
primers were used singly to amplify genomic segments which were flanked
by inversely orientated, closely spaced, identical microsatellite
sequences. One of the polymorphic bands, a 900 base pair band, was
completely linked to the Sr39 and Lr35 rust resistance genes in the
segregating population used in this study. After cloning and sequencing
this polymorphic band, the inter-simple sequence repeat marker was
converted to a sequence characterized amplified region marker by
designing primer sets which amplify a single, easily resolved band from
DNA of plants with Sr39/Lr35 genes. This marker is present in six wheat
lines carrying the Sr39 and Lr35 genes on the translocated chromosome
segment from Ae. speltoides, The marker has facilitated efforts to
breed Canada Prairie Spring and Canada Western Extra Strong lines with
these rust resistance genes