Screening the Zymoseptoria tritici population in Turkey for resistance to azole and strobilurin fungicides

Acclimatized fungal diseases in wheat crops pose a severe threat to world wheat production. Zymoseptoria tritici, which causes Septoria tritici blotch (STB), is known as a devastating latent necrotrophic fungal pathogen that causes a significant yield loss, especially in Europe and in other wheat-growing countries. This fungal pathogen developed rapid resistance against new and old fungicides and has become a major threat to future wheat crops. Strobilurines and Azoles are the main group of contact and systemic fungicides along with succinate dehydrogenase inhibitors with reliable results to control the Z. tritici all over the world. However, many reports from Europe described the presence of resistance in Z. tritici against these fungicides. In the present study, a total of 102 isolates of Z. tritici were collected from five regions (Central Anatolia, Southeastern Anatolia, Marmara, Aegean, and the Mediterranean) of 19 provinces of Turkey to check the presence of target-site mutation at a molecular level to these two main fungicides. Azole target-site mutation in the CYP51 gene was checked by sanger sequencing while the strobilurin resistance mutation in the Cytb gene was confirmed by using PCR-RFLP using the FnuHI restriction enzyme. The obtained results from the two genes revealed some target-site mutations, however no known amino acid changes that cause resistance against these two main group fungicides in Turkish isolates have been detected. We concluded that the severe infection of STB pathogen in Turkish wheat growing may be still manageable with these fungicides although the resistance tests must be conducted for certainity.