Potential of Cyclopiazonic Acid Production in Non-Aflatoxinogenic Strains of Aspergillus flavus of Iranian Pistachio

Introduction: Biocontrol of toxigenic populations with nontoxigenic strains has long been introduced as an effective method of reducing aflatoxins in crops such as corn, cottonseed, oilseeds, and pistachios. But if these nontoxigenic strains produce cyclopiazonic acid, being a less important fungal secondary metabolite, they may have unwanted negative consequences. Materials and Methods: In this study, it has been attempted to investigate the production of cyclopiazonic acid in 58 non-aflatoxigenic strains and one aflatoxigenic strain of Aspergillus flavus obtained from pistachio soil and nuts of orchards in Kerman, Yazd, Khorasan Razavi, Esfahan, Qom, Semnan and Markazi provinces. For evaluating the production of cyclopiazonic acid, the isolates were first cultured in CYA medium, and for each isolate, three inoculations were kept in a dark incubator at 25°C for 14 days. Then, the ability to produce cyclopiazonic acid was assayed by high performance liquid chromatography (HPLC). Results: The production of cyclopiazone in different isolates was 6.951-357.6 mg/l. The results showed that out of 59 A. flavus isolates, as many as 44 isolates were not able to produce cyclopiazonic acid. Also, the percentage of non-aflatoxinogenic isolates that were not able to produce cyclopiazonic acid has been estimated to be 76%. Conclusion: The results of this study can be useful in selecting suitable and efficient isolates for biological control of aflatoxin in orchards.