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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 #404614
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: Structure of Aspergillus flavus populations associated with maize in Greece, Spain, and Serbia; implications for aflatoxin biocontrol on regional scale

Author
item OUADHENE, MOHAMED - Catholic University Of The Sacred Heart Italy
item Callicott, Kenneth
item ORTEGA-BELTRAN, ALEJANDRO - International Institute Of Tropical Agriculture (IITA)
item Mehl, Hillary
item COTTY, PETER - Ocean University Of China
item BATTILANI, PAOLA - Catholic University Of The Sacred Heart Italy

Submitted to: Environmental Microbiology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2024
Publication Date: 4/17/2024
Citation: Ouadhene, M.A., Callicott, K.A., Ortega-Beltran, A., Mehl, H.L., Cotty, P.J., Battilani, P. 2024. Structure of Aspergillus flavus populations associated with maize in Greece, Spain, and Serbia; implications for aflatoxin biocontrol on regional scale. Environmental Microbiology Reports. 16. Article E13249. https://doi.org/10.1111/1758-2229.13249.
DOI: https://doi.org/10.1111/1758-2229.13249

Interpretive Summary: Aflatoxins are cancer-causing toxins that contaminate food after growth by the mold Aspergillus flavus and closely related species. A. flavus, a frequent cause of aflatoxim contamination around the world, contains both isoltes that produce aflatoxins and those that do not. These latter strains, called "nonaflatoxigenic," have been harnessed since the 1990s as natural biological aflatoxin control after application to cropsy by outcompeting toxin producing strains that are found naturally in the environment. Aflatoxin contamination has been recognized as a growing problem in southern Europe, especially in Italy, Spain, Greece, and Serbia. Prior work developed a native nonaflatoxigenic strain, MUCL54911, into a biological control product registered in Italy as AF-X1. This study used genetic markers to characterize naturally occurring A. flavus strains in Greece, Serbia, and Spain to better understand how fungal populations in these three countries related to each other and to those in Italy. As seen in other areas, there was extremely high genetic diversity among A. flavus isolates from southern Europe, and genetic evidence suggests these populations are largely evolving through clonal reproduction. Some strains in each country were found to be very closely related to MUCL54911, which suggests that AF-X1 could be used to control aflatoxins with little ecological risk that might come from introducing an entirely novel genetic type.

Technical Abstract: The ubiquitous fungus Aspergillus flavus is the most frequently identified producer of aflatoxins. This species is divided into two morphotypes, the L and S strains, with the L strain being the most widely distributed. Non-aflatoxigenic members of the L strain are used on various continents as active ingredients of biopesticides directed at preventing aflatoxin contamination by competitive displacement. However, the diversity of the A. flavus L strain in Europe has not received detailed attention. The current research examined genetic diversity of A. flavus across southern Europe in order to gain insights into population structure and evolution of this species in Europe and to evaluate the prevalence of MUCL54911, the active ingredient of the commercial aflatoxin biocontrol product AF-X1. A total of 2,173 Aspergillus flavus isolates recovered from maize collected across Greece, Spain, and Serbia in 2020 and 2021 were subjected to single sequence repeat (SSR) genotyping. The analysis revealed high diversity within and among countries and dozens of haplotypes shared among countries. Linkage disequilibrium analysis indicted asexual reproduction and clonal evolution of A. flavus reseident in southern Europe. Moreover, haplotypes closely related to MUCL54911 were found to belong to the same vegetative compatibility group (VCG) and that group, IT006, was relatively common in all three countries. The results indicate that IT006 is endemic and well-adapted to the environment of southern Europe and should be utilized as a aflatoxin mitigation tool for maize across the region.