Resistance of some wheat cultivars to the main race of tan spot disease in Ardabil province

 In this study, ninety- six isolates of Pyrenophora tritici-repentis from Ardabil province were collected and identified. According to the results of molecular data and considering the geographical area, thirty isolates were selected for race identification studies in greenhouse. Genetic diversity was detected between three fungal populations including Parsabad, Germi and Bilesavar in Ardabil province. During the study of gene diversity, the amount of gene flow (Nm) was equal to 1.6890 and the amount of Gst was equal to 0.2284. The rate of genetic diversity for the whole population (Ht) was 0.2993. PhiPT was estimated to be 0.259 (p> = 0.010). According to the results of AMOVA, 74% of total variance was attributed to within populations while only 26% of that was related to between populations. Race1 of the pathogen as the main race was used in Ardabil province to evaluate the resistance of forty wheat cultivars in greenhouses. Inoculation was carried out using fungal conidial suspensions and fungal culture filtrates. The Mean Disease Index in different cultivars was calculated and compared. The results of cultivars' reaction showed that 90% of studied wheat cultivars are in the susceptible group to the pathogen. Four cultivars of Morvarid, Moghan 3, Ehsan and Darya, which together comprise 10% of the studied cultivars, were included in the resistant group. The use of these resistant cultivars is recommended for areas with a high possibility of disease outbreaks. In addition, breeders can use the sources of resistance for future breeding programs.