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
gene
