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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: Susceptibility to aflatoxin contamination among maize land races from Mexico

Authors
item Ortega-Beltran, Alejandro -
item Guerrero-Herrera, Manuel -
item Ortega-Corona, Alejandro -
item Vidal-Martinez, Victor -
item Cotty, Peter

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 10, 2014
Publication Date: N/A

Interpretive Summary: Aflatoxins are toxic fungal metabolites that can inhibit human development, cause cancer, and even induce death. Occurrence of these toxins greatly reduces the markets into which crops can be sold. Aflatoxin contamination of maize is a significant problem in many warm production regions. Mexico has many warm production regions and the population relies on maize for over half of the calories it consumes. Mexico is also the center of origin for maize and across Mexico, native populations cultivate traditional Native Land Races (NLR) of maize as preferred sources of nutrition. It is unknown if cultivating traditional NLR influences exposure of Mexican populations to aflatoxins. In order to assess the influence of NLR cultivation on aflatoxin exposure 74 NLR accessions were collected from 2006 to 2008 from two regions of Mexico and the collected maize was evaluated for susceptibility to aflatoxin contamination. Highly resistant and highly susceptible NLRs were found. The work indicates that us of NLRs in Mexico does not increase human exposure to aflatoxins. Furthermore, the NLRs were found to be potential sources of genes for resistance to both A. flavus infection and aflatoxin contamination that may contribute to the breeding of commercially acceptable maize hybrids with reduced susceptibility to aflatoxins.

Technical Abstract: Maize, the critical staple food for billions of people, was domesticated in Mexico about 9,000 YBP. Today, a great array of maize land races (MLRs) across rural Mexico is harbored in a living library that has been passed among generations since before establishment of the modern state. MLRs have been selected over hundreds of generations by ethnic groups for adaptation to diverse environmental settings. The genetic diversity of MLRs in Mexico is an outstanding resource for development of maize cultivars with beneficial traits. Maize is frequently contaminated with aflatoxins by Aspergillus flavus and resistance to accumulation of these potent carcinogens has been sought for over three decades. However, MLRs from Mexico have not been evaluated as potential sources of resistance. Variation in susceptibility to both A. flavus reproduction and aflatoxin contamination was evaluated on viable maize kernels in laboratory tests that included 74 MLR accessions collected from 2006 to 2008 in the Central West and North West regions of Mexico. Resistant and susceptible MLR accessions were detected in both regions. The most resistant accessions accumulated over 99% less aflatoxin B1 than the commercial hybrid control Pioneer P33B50. Accessions supporting lower aflatoxin accumulation also supported reduced A. flavus sporulation. Sporulation on the MLRs was positively correlated with aflatoxin accumulation (R = 0.5336, P < 0.0001) suggesting resistance to fungal reproduction is associated with MLR aflatoxin resistance. Results of the current study indicate MLRs from Mexico are potentially important sources of aflatoxin resistance that may contribute to the breeding of commercially acceptable and safe maize hybrids and/or open pollinated cultivars for human and animal consumption.

Last Modified: 12/22/2014
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