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Title: Aflatoxin-producing fungi in maize field soils from sea level to over 2000 masl: A three year study in Sonora, Mexico

Author
item ORTEGA-BELTRAN, ALEJANDRO - University Of California
item JAIME, RAMON - University Of Arizona
item Cotty, Peter

Submitted to: Fungal Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2014
Publication Date: 12/19/2014
Citation: Ortega-Beltran, A., Jaime, R., Cotty, P.J. 2014. Aflatoxin-producing fungi in maize field soils from sea level to over 2000 masl: A three year study in Sonora, Mexico. Fungal Biology. 119:191-200.

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 to which crops can be sold. The fungus named Aspergillus flavus is the primary cause of aflatoxin contamination of several crops. In order to understand the epidemiology of contamination, populations of A. flavus must be monitored and characterized. This monitoring requires careful sampling that must take into consideration influences of toplogy and climate. In order to improve sampling efficiency and to understand variation in populations over space, populations of A.flavus were characterized across different elevations and agroecological zones in Mexico. Cropping system was found to be a more important influence on fungal community structure than elevation. However, agroecological zones need to be taken into consideration when designing sampling. Several atoxigenic strains, possibly useful in managing aflatoxins, were found across agroecological zones suggesting biocontrol isolates that might be successful across broad regions of Mexico might be selected.

Technical Abstract: Aflatoxins, highly toxic carcinogens produced by several members of Aspergillus section Flavi, contaminate crops in temperate zones. Maize is cultivated from 0 to 2,100 masl under diverse growing regimes in the state of Sonora, Mexico. This is typical of the nation. In order to design sampling strategies across Mexico, aflatoxin-producing fungal communities associated with maize production during 2006, 2007 and 2008 in Sonora were investigated in diverse agro-ecological zones (AEZ) at varying elevations. Fungal communities were dominated by the A. flavus L strain (46%), but variation occurred between years and among AEZ. Insights on the dynamics and stability of aflatoxin-producing fungal communities across AEZ are discussed. Several atoxigenic isolates with potential to be used as biocontrol agents for aflatoxin mitigation were detected in all AEZ. The characteristics of each AEZ had minimal influences on fungal community structure and should not be a major consideration for future sampling designs for Mexico.