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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #430735
Research Project: Improvement of the Aflatoxin Biocontrol Technology Based on Aspergillus flavus Population Biology, Genetics, and Crop Management Practices

Location: Pest Management and Biocontrol Research

Title: Population structure of Aspergillus flavus in hazelnuts from Azerbaijan: Genetic diversity, clonality and biocontrol implications

Author
item CASU, ALESSIA - Università Cattolica Del Sacro Cuore
item Callicott, Kenneth
item Mehl, Hillary
item BATTILANI, PAOLA - Università Cattolica Del Sacro Cuore

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2026
Publication Date: 6/23/2026
Citation: Casu, A., Callicott, K.A., Mehl, H.L., Battilani, P. 2026. Population structure of Aspergillus flavus in hazelnuts from Azerbaijan: Genetic diversity, clonality and biocontrol implications. Plant Disease. https://doi.org/10.1094/pdis-02-26-0294-re.
DOI: https://doi.org/10.1094/pdis-02-26-0294-re

Interpretive Summary: Aflatoxin contamination by the fungus Aspergillus flavus is a persistent and costly challenge for producers of crops including corn, peanuts, and tree nuts with significant implications for food safety and public health. In this study, hazelnut samples were collected from multiple locations throughout Azerbaijan both pre- and post-harvest over three years. Fungi were isolated from hazelnut samples, and the population structure and occurrence of non-aflatoxigenic biocontrol genotypes of A. flavus were examined. The A. flavus population associated with hazelnuts was genetically diverse, and isolates genetically similar to biocontrol strains used for mitigation of aflatoxin contamination in both Europe and the U.S. were identified. Data generated from this study provide insights into the population structure and dynamics of aflatoxin-producing fungi and can be used as a basis for developing and improving aflatoxin biocontrol mitigation strategies in diverse cropping systems.

Technical Abstract: Aflatoxin contamination is a growing concern in hazelnut production across the Caucasus, particularly due to its health risks and the economic impact in markets with strict safety standards, such as the European Union. This study examined the genetic diversity and population structure of Aspergillus flavus, the main source of aflatoxin, in three key hazelnut regions of Azerbaijan: Zaqatala, Qabala, and Khachmaz. It also assessed the presence of non-aflatoxigenic strains, which are valuable for biological control by outcompeting toxin-producing variants. A total of 710 A. flavus isolates were analyzed using simple sequence repeat (SSR) markers, revealing 374 distinct haplotypes and high genetic diversity across regions, seasons, and production stages. Linkage disequilibrium analysis indicated a primarily clonal reproduction pattern. Among 477 clone- corrected isolates, several haplotypes closely matched non-aflatoxigenic biocontrol strains MUCL54911 and AF36, the active ingredients in AF-X1 and AF36 Prevail, repectively. These findings establish a genetic baseline for A. flavus in Azerbaijani hazelnut systems and support the potential use of MUCL54911 or AF36 for local biocontrol efforts aimed at reducing aflatoxin contamination.