Resistance of Zymoseptoria tritici populations to some active ingredients of fungicides

During the different stages of its development, wheat is possible infected by many plant pathogens. One of the most common is Zymoseptoria tritici, the causal agent of the disease called Septoria Tritici Blotch (STB). The most common strategy in the Z. tritici disease management is treating plants with fungicides. Unfortunately, this plant pathogen as many others evolved resistance towards some of the most commonly used fungicidal classes. The aim of this study was to detect the resistance of Z. tritici to strobilurin fungicide azoxystrobin. During the April 2017, around 300 plant samples were collected from 11 geographical regions in the Czech Republic. From those plant samples, 52 monosporic Z. tritici isolates were obtained and tested for the presence of the resistance. The fungicide resistance was measured and detected by laboratory agar dilution biotest and molecular methods as a CAPS marker (Cleaved Amplified Polymorphic Sequences) and qPCR (Quantitative Polymerase Chain Reaction). By agar dilution biotest, resistance to azoxystrobin was confirmed in 54% of total 52 analysed isolates. By CAPS marker analysis, the presence of G143A mutant allele of the mitochondrial cytochrome b gene, linked to the fungicide resistance, was confirmed in all selected isolates marked as resistant in the biotest. The DNA of one infected leaf sample collected from the field marked as 17Zt212 was isolated and tested by the qPCR method. In the field sample (17Zt212), the 4% of the Z. tritici population was found to be resistant to fungicide azoxystrobin