DNA restriction fragment length polymorphisms in the wheat stem rust fungus, Pucinia graminis tritici

A cDNA library was synthesized from poly A⁺ RNA extracted from germinated urediospores of the wheat stem rust fungus, Puccnia graminis tritici (race 343-1,2,3,5,6). The library was used as a source of probes to detect RFLPs in genomic DNA from three major races of P. graminis tritici in Australia, as well as two formae speciales of P. graminis. DNA extracted from another Puccnia species infecting wheat, P. recondita tritici (wheat leaf rust), was included in the analysis. Nine different cDNA probes were analysed, and all detected polymorphisms between the races and formae speciales of P. graminis that were tested. Seven detected polymorphisms between P. graminis and P. recondita; the remaining two probes showed no detectable homology to P. recondita genomic DNA. The potential applications of RFLP markers to study the origin of genetic variability in P. graminis tritici are discussed.