Genetic diversity and pathogenicity among Paecilomyces formosus isolates the causal agent of pistachio dieback in Khorasan Razavi and Yazd provinces

In this research, genetic diversity and pathogenicity of Paecilomyces formosusisolates, causal agent of die-back disease of pistachio trees in Yazd and Khorasan Razavi provinces were investigated. Genetic diversity of 50 selected isolates using SSR markers, showed a high degree of polymorphism between isolates. Cluster analysis based on UPGMA algorithm and Jaccard's similarity coefficient, divided the isolates into 11 groups with 75% similarity level. Shannon index, Principal coordinates analysis (PCoA) and analysis of molecular variance (AMOVA) revealed that the highest genetic variation (81%) was disturbed among isolates and genetic variation within isolates was determined as 19%. Between used primers, PVar15 was more appropriate than others to study of genetic diversity of isolates. Study of pathogenicity test and mean comparison mean of data showed that isolates of Mehriz and Abarkoh regions in Yazd province had the most and lowest aggressive isolates, respectively. Our results indicated that there is a specific relationship between the isolates of each region whereas no relationship was identified between related isolates belongs to two provinces and their genetic diversity.