Efficacy of wheat genotypes and Stb resistance genes against Iranian isolates of Zymoseptoria tritici

Septoria tritici blotch (STB), caused by Zymoseptoria tritici has been considered one of the important diseases of wheat in Europe and elsewhere including Iran. The most economical strategy to control the disease is the use of genetic resistance. To this aim, this study was conducted to identify new sources of resistance to STB and to investigate the effectiveness of known Stb genes against six Iranian isolates of Z. tritici. Genetic variability analysis using random amplified polymorphic DNA (RAPD) markers revealed high polymorphic banding patterns indicating that a high genetic variability existed among the isolates. Inoculation assays identified 116 isolate-specific resistances among all interactions (n = 420). Of 52 genotypes, 26 wheat genotypes showed no isolate-specific responses and were susceptible to all isolates, which may explain increasing epidemics of Z. tritici occurring in major wheat-growing regions in Iran. Five genotypes were highly resistant to all isolates. Effectiveness determination of Stb genes revealed that Iranian isolates have a broad virulence spectrum against most of the known Stb genes. Among all Stb genes, Stb15 and Stb16/Stb17 in cultivars Arina, Riband and M3 were the most effective resistance genes and conferred resistance to all isolates tested. Hence, these genes should be effective in breeding programs in Iran to control the disease.