During 2012, one hundred-thirty soil isolates of A. flavus were collected from commercial pistachio orchards in two main production regions including Rafsanjan (Kerman Province, south-eastern of Iran) and Damghan (Semnan Province, central north of Iran) and assayed for vegetative compatibility groups (VCGs). The sixteen and twenty VCGs were identified for 41 and 37 nit-mutant producing isolates of A. flavus. The variability in morphology was found amongA. flavus isolates from different VCGs, but no variability among isolates from the same VCG. VCG diversity for A. flavus isolates from Damghan and Rafsanjan was 54 and 39%, respectively. The high VCG members in small size-isolates ofA.flavus from Damghan indicated high genetic variability in fungal population. Because of a few number ofsclerotium-producing isolates of A. flavus, we did not determine the relationships between sclerotiumproduction with VCGin two pistachio production regions. This study was the first to determine the strain and VCG diversity of soil isolates of A. flavus from pistachio orchards.

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