Genetic Structure of Macrophomina phaseolina Populations, the Causal Agent of Sesame Charcoal Rot Disease in Iran

Abstract

Charcoal rot disease, caused by the fungus <i>Macrophomina phaseolina</i>, is one of the most important diseases of Sesame (<i>Sesamum indicum</i>) all over the world. However, the population biology of <i>M. phaseolina</i> is poorly understood. In this study, <i>M. phaseolina</i> isolates from five different regions of Iran (Khuzestan, Fars, Bushehr, Hormozgan, and Kohgiluyeh & Boyer-Ahmad provinces) (n=200) were analyzed for genetic variation using inter simple sequence repeats marker. In total, 152 unique haplotypes were identified among the 200 <i>M. phaseolina</i> isolates, and gene diversity (H=0.46–0.84) and genotypic diversity were high in each of the regions. The structure analysis clustered five Iranian populations into two distinct groups, the individuals from group 1 were assigned to the Bushehr population and the individuals from Khuzestan, Fars, Hormozgan and Kohgiluyeh & Boyer-Ahmad were aggregated and formed group 2. The results matched with genetic differentiation and gene flow among regions. Analyses of the distribution of gene diversity within and among five Iranian populations were 61% and 39%, respectively. Our results showed that infected seeds are thought to be the dominant mechanism responsible for the spreading of the pathogen in southern parts of Iran. In summary, it is essential to have local quarantine and prevent seed exchanges between geographical populations to restrict the dispersal of pathogen over long distances and provide certified seeds in Iran.