Abstract:
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.
Keywords: Barley, Genetic diversity, Rhynchosporium secalis, Scald.
