Molecular Marker Analysis of Stem Rust Resistance Genes in Some Iranian Wheat Genotypes

Stem rust caused by Puccinia graminis f. sp. tritici is a destructive wheat disease worldwide, traditionally controlled by the Sr31 resistance gene for many years until the virulent strain; Ug99 emerged in 1999. The new pathotype threatened the global wheat production, and was later detected in Hamedan and Lorestan provinces of Iran. To tackle this disease, it is necessary to find new sources of resistance against the Ug99 race and its variants. Ninety-five Iranian wheat genotypes were analyzed for the presence of the stem rust resistance genes; Sr2, Sr22, Sr24, Sr25 and Sr31 with the help of several CAPS, STS and SSR markers. Seeds of the tested genotypes and Thatcher as negative control and five isolines as positive controls were sown in pots in a greenhouse. After DNA extraction, polymerase chain reaction (PCR) was performed using primers for the corresponding markers. The Iag95 marker demonstrated the presence of Sr31 in 10 genotypes. Nine genotypes showing the Gb associated band, carried Sr25. J09, the linked marker with Sr24, detected this gene in only two genotypes. No genotype showed the bands for markers linked to Sr2 or Sr22 genes. The combined presence of Sr24 and Sr31 was identified in six genotypes. So far, neither Ug99 nor its variants have virulence for Sr2, Sr22 and Sr25 suggesting they could be transferred from donor sources to suitable lines for commercial uses.

Automated summary

Analysis of 95 Iranian wheat genotypes revealed presence of Sr31 in 10 genotypes, Sr25 in 9 genotypes, Sr24 in 2 genotypes, and no presence of Sr2 or Sr22. Additionally, the combination of Sr24 and Sr31 was identified in 6 genotypes, suggesting potential transfer of these resistance genes for commercial uses.