Polyphasic identification of Cercospora cf. sigesbeckiae as causal agent of cercospora leaf spot of oilseed plants soybean, sesame and rapeseed in Golestan and Mazandaran provinces

Soybean, sesame and rapeseed are important industrial crop plants in the world and Iran. Cercospora leaf spot is a significant threat to the production of these crops specially in soybean, worldwide. In a field survey in Golestan and Mazandaran provinces, the widespread distribution of leaf spot symptoms on soybean, sesame and rapeseed was observed. In order to identify the fungal agents associated with this disease, symptomatic leaves were collected from the field and taken to the laboratory. Single spore cultures derived directly from leaf spots. In total, 50 isolates were obtained of which eight isolates from soybean, four isolates from sesame and four isolates from rapeseed were identified based on sequences of six genomic loci (ITS, act, tef1, cmdA, his3 and gapdh), host plant, and morphological data. The results of phylogenetic analysis have revealed that Cercospora cf. sigesbeckiae is a causal agent of cercospora leaf spot of soybean, sesame and rapeseed in Golestan and Mazandaran provinces. To our knowledge, this is the first report of Cercospora cf. sigesbeckiae for Iran mycobiota and its first report on sesame and rapeseed in the world.