Genetic Diversity of Isolates of Macrophomina phaseolina Associated with Cowpea from Brazil Semi-Arid Region

Cowpea crops have the highest social and economic relevance to Brazil, being the food base of families mainly in the semi-arid areas of the country. Charcoal rot caused by Macrophomina phaseolina is an economically important disease of cowpea that can cause significant reductions in bean yield. This study aimed to access the genetic diversity of M. phaseolina isolates obtained from cowpea grown in the Pernambuco semi-arid region, by molecular analysis. Fifty-one isolates, collected from municipality of Belém do São Francisco from cowpea plants and displaying typical symptoms and signs of charcoal rot, were studied using inter-simple sequence repeat (ISSR) markers. Unweighted pair-group method using arithmetic means (UPGMA) clustering of data showed that isolates clearly differentiate into two groups. The group 1 comprises the majority of isolates and the group 2 contains two isolates, isol46 and isol47. The highest similarity index (0.9) was observed between the isolates isol22 and isol35 and the lowest similarity index (0.2) was observed between isol37 and isol46 isolates. Our results revealed that the ISSR-PCR fingerprinting patterns were useful for differentiating M. phaseolina isolates from V. unguiculata plants sampled. Therefore, genetic characterization of this fungus is of importance for the effective disease management.