To study the genetic diversity of isolates of Cytospora chrysosperma, the main causal agent of Cytospora canker, we collected the infected samples from the major walnut cultivation areas in 12 provinces of Iran. 58 representative isolates out of a total of 147 isolates were selected according to their geographical origins to study their genetic diversity using random amplified polymorphic deoxyribonucleic acid (RAPD) marker. Ten of 20 random primers amplified reproducible polymorphic banding patterns. Cluster analysis of the data using Centroid method and Jaccard´s similarity coefficient, divided the isolates into six groups, showing a high genetic diversity among populations of C. chrysosperma. Although there was no correlation between geographical origins and the resulting groups of RAPD analysis, but the amount of observed polymorphism (94%) indicated the adequacy of the molecular marker RAPD, for studying genetic diversity in C. chrysosperma isolates. This is the first report on the study of genetic diversity of populations of C. chrysosperma using RAPD marker.
