بررسی مقاومت رقم گندم حامل ژن مقاومت Stb6 در برابر تعدادی از جدایه‌های ایرانی Zymoseptoria tritici

Zymoseptoria tritici is the causative agent of wheat septoria leaf spot, one of the most important fungal pathogens of wheat. During the infection cycle, Z. tritici produces and secretes a set of pathogenicity factors, among which effector AvrStb6 acts as an avirulence factor in the interactions between IPO323 isolate and Shafir wheat cultivar. Research has shown that the avirulence AvrStb6 protein is recognized by the Stb6 resistance protein present in the Shafir cultivar, and this detection leads to the non-contamination of this variety by Z. tritici, which contains the AvrStb6 effector coding gene. It is clear that the AvrStb6-Stb6 interaction follows the gene-for-gene model. In this study, samples were taken from the Khuzestan and Ardabil provinces, which are the hotspots of this disease, in 2023. To obtain Z. tritici isolates, leaf segments were attached to glass slides with tape and kept under high humidity conditions at 18°C for 12–24 hours until the pycnidia produced cirri containing pycnidiospores. Subsequently, the produced pycnidiospores were transferred to a PDA medium and kept at 18°C for 5–7 days. Samples were purified on YMDA (Yeast extract 4 g/l, malt extract 4 g/l, dextrose 4 g/l, agar 15 g/l) medium and for long-term storage, spore suspension was prepared in 30% glycerol solution and transferred to -80 °C. To perform the pathogenicity test, the Shafir cultivar, carrying the Stb6 resistance gene was selected, and several Iranian Z. tritici isolates were inoculated on this cultivar under greenhouse conditions. In addition to the disease-resistant cultivar, a susceptible cultivar, Tajan, was also selected as a positive control. The result of this research showed that some of the Iranian Z. tritici isolates were able to break the resistance of the Shafir cultivar. The results of this research can be used to select resistant cultivars considering their durability.