Parastagonospora nodorum blotch disease is a major wheat pathogen in most wheat-growing areas of the world. Acollection of 268 Parastagonospora isolates were collected from naturally infected wheat fields of four provinces from Iran: Kogiluyeh and BoyerAhmad, Khuzestan, Golestan and Fars. Based on morphological characteristics, 219 P. nodorum isolates were isolated from wheat and Phalaris arundinacea . 49 P. avenae isolates were found on Avena sativa , Phalaris arundinacea , Bromus hordeaceus and Aegilops tauschii . The complete ITS region and partial nucleotide sequences of the ?-tubulin and ?-xylosidase genes were concatenated and used for phylogenetic analysis of Parastagonospora isolates. P. nodorum formed the largest clade, identified on wheat and Phalaris arundinacea . P. avenae f.sp. avenaria (Paa) were the second largest clade, found on Phalaris arundinacea and Avena sativa. The third clade P. avenae f.sp. tritici 5 (Pat5) was isolated from Phalaris arundinace a , Bromus hordeaceus , and Aegilops tauschii . Pat5 and Paa are reported from Iran for the first and also all of the identified hosts are new host to the world. In this study, P. nodorum isolates from Iran were analyzed for genetic variation using 11 simple sequene repeat (SSR) markers developed from the genome sequence of the fungus. Atotal of 100 alleles were detected anaysing 11 microsatellite loci across all 217 P. nodorum isoates, of the 217 isolates analyzed, 213 haplotypes were detected. All of Iranian wheat regions( four regions) had a high gene diversity, genotypic diversity and clonal fractions. High gene flow and low genetic differentiation were observed among Ghachsaran and Norabad. Furthermore, the high genetic differentiation and low gene flow were detected between south of Iran (Ghachsaran, Noorabad and Dezphool) and north of Iran (Gorgan). Population analysis using STRUCTURE revealed that Iranian isolates were subdivided into three populations coreesponding to the the three regions (South 1, South2, North). The results showed that sexual recombination is possible into identified three populations, because Linkage disequlibrium tests ( and ) supported the hypothesis of random mating, both mating types ( MAT1 and MAT2 ) were present and frequencie of them were almost equal at these regions.The center of origin of Parastagnospora nodorum wasn’t clear despite earlier intensive global population genetic and Phylogeographical studies. Our Results revealed the high level genetic diversity and allelic richness among Iranian populations. We compared neutral marker diversity with diversity at effector loci to clarify the origin of P. nodorum. We detected the Iranian population harboring both the highest sequence diversity for necrotrophic effectors (NEs) and the highest diversity at neutral loci in comparison to global P. nodorum populations previously reported. In fact, these findings support that Iran can be the center of origin of P.nodorum. Keywords : Effectors, Mating types, Population genetics, Phylogeny, Morphologhy, SSR