Virulence analysis of wheat stem rust isolates (Puccinia graminis f. sp. tritici) in Iran using differential lines

Wheat stem rust caused by the fungus Puccinia graminis f. sp. tritici is one of the most destructive diseases. Here, we collected 43 stem rust isolates from six provinces of Iran during 2020–2022 and assessed variability in their virulence on 20 North American differential lines carrying one of the stem rust resistance genes. More than 90% of isolates were virulent on lines with gene Sr5, Sr9d, Sr9g, Sr30, Sr36, Sr38, SrTmp and SrMcN and the least virulent on those with Sr31 (16.2%) and Sr24 (0%). The majority of isolates belonged to races TKTTF, TTTTF, and TTTTK. Races TTTTK, TKTTK and PTTTK are new in Iran.