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United States Department of Agriculture

Agricultural Research Service

Research Project: Reducing Aflatoxin Contamination Using Biological Control and Crop Management

Location: U.S. Arid Land Agricultural Research Center

Title: Structure analysis of an Aspergillus flavus kernels population in North Italy. First analysis of an Aspergillus flavus kernels population based on vegetative compatibility groups in Northern Italy

Authors
item Mauro, Antonio -
item Battilani, Paola -
item Giorni, Paola -
item Pietri, Amedeo -
item Callicott, Kenneth
item Cotty, Peter

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2013
Publication Date: March 1, 2013
Citation: Mauro, A., Battilani, P., Giorni, P., Pietri, A., Callicott, K.A., Cotty, P.J. 2013. Structure analysis of an Aspergillus flavus kernels population in North Italy. First analysis of an Aspergillus flavus kernels population based on vegetative compatibility groups in Northern Italy. International Journal of Food Microbiology. 162(1):1-7.

Interpretive Summary: Aflatoxins are toxic fungal metabolites that impair the immune system and cause cancer in humans. These poisons are produced by a diverse group of fungi. In order to develop management tools for limiting contamination, it is necessary to identify the fungi that cause the majority of aflatoxin contamination. Aflatoxin contamination of maize has been a problem in portion of Italy over the past decade. As part of efforts to identify the causal agents of aflatoxin contamination in Italy, we examined the fungi contaminating maize in Italy. In contrast to certain other regions, the L strain of A. flavus, a fungus also common in the United States, was found to be the primary causative agent of aflatoxin contamination of maize in Italy. During the process several genetic groups of A. flavus of potential value as biological control agents were also discovered. The results suggest that management strategies aimed at aflatoxin-producing members of the L strain of A. flavus may be most effective at reducing aflatoxin contamination.

Technical Abstract: In order to gain insight into the causal agents of aflatoxin contamination of maize in Italy, populations of Aspergillus flavus on maize produced in the most affected area were characterized. Forty-six percent of A. flavus, isolated from maize kernels collected in 5 districts of northern Italy between 2003 and 2010, were unable to produce detectable levels of aflatoxins. The genetic diversity of the population was assessed by analysis of vegetative compatibility groups (VCGs) and presence or absence of several aflatoxin biosynthesis genes. Forty-eight VCGs were identified through complementation between nitrate non-utilizing mutants. Twenty-five VCGs contained only atoxigenic isolates, and the remaining 23 only aflatoxin producers. Members of the largest atoxigenic VCG (IT6) were found in 4 of the 5 districts sampled. Six deletion patterns of genes in the aflatoxin biosynthesis gene cluster were detected. No deletions in the cluster were detected for twelve atoxigenic isolates and 10 had the entire cluster deleted. One isolate had a deletion pattern only seen once before in Nigeria. The basis for initial selection of endemic atoxigenic strains of A. flavus for biological control of aflatoxin contamination of maize in Italy is provided.

Last Modified: 10/24/2014
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