Genetic Diversity of Iranian Isolates of Barley Scald Pathogen (Rhynchosporium secalis) Making Use of Molecular Markers

Leaf blotch disease of barley, caused by Rhynchosporium secalis is a major disease of barley in Iran. Its worldwide occurrence and economic importance in barley production has motivated studies on the population genetic structure of this pathogen. Random Amplified Polymorphic DNA (RAPD) method was utilized to investigate the genetic diversity of populations of R. secalis isolated from barley leaves. A total of 94 isolates, representing five geographically distinct populations, were collected from diverse climatic regions in Iran. Genetic diversity was studied using eleven RAPD primers. Out of a total of 119 fragments generated by random decamer primers, 89 (75.1%) were polymorphic with an average of 8.1 polymorphic fragments per primer. Cluster analysis of RAPD data using UPGMA and simple matching coefficient method distinguished 33 main groups at 75% similarity level. The similarity between isolates ranged from 0.62 to 0.89. In total, 42 molecular phenotypes (haplotype) were distinguished among the 94 isolates by 11 RAPD primers. Haplotype one was found in all the five regions of Iran surveyed. Some haplotypes were specific to a single region while others found in several regions. There was little correlation observed between genetic vs. geographical distance suggesting that they were independent of each other.