In order to evaluate genetic diversity of Cytospora chrysosperma isolates, the main causal agent of Cytospora canker, infected samples from major walnut cultivation areas in 12 provinces of Iran (Hamedan, Kurdistan, Kermanshah, Ilam, West Azarbaijan, Zanjan, Markazi, Lorestan, Chaharmahal va Bakhtiari, Isfahan, Kohgiloye va Boyerahmad and Fars) were collected. Out of 147 isolates, 58 representatives were selected according to their geographical origins in order to study their genetic diversity using ISSR marker. Twelve out of 20 tested random primers generated a total of 119 amplicons among the isolates. Cluster analysis of data using Centroid method and Jaccard’s similarity coefficient, divided the isolates into seven groups, showing a high genetic diversity among populations of C. chrysosperma. Although there was no correlation between geographical origins and the resulting groups of ISSR analysis, but the amount of observed polymorphism (95.8%) was indicated the adequacy of the molecular marker, ISSR, for studying genetic diversity in C. chrysosperma isolates. According to our knowledge, this is the first report on the study of genetic diversity of populations of C. chrysosperma using ISSR marker.
