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

• Elevation had minor influences on community structures of aflatoxin-producing fungi.
• Agro-ecological zones did not favour particular groups of aflatoxin-producing fungi.
• Cropping systems may influence quantities and frequencies of species among AEZ.
• Several atoxigenic isolates were identified in each AEZ.
• Sampling multiple years will yield realistic estimations of community structures.

Aflatoxins, highly toxic carcinogens produced by several members of Aspergillus section Flavi, contaminate crops in temperate zones. In the state of Sonora, Mexico, maize is cultivated from 0 to 2100 masl with diverse cultivation practices. This is typical of the nation. In order to design better sampling strategies across Mexico, aflatoxin-producing fungal communities associated with maize production during 2006, 2007, and 2008 in Sonora were investigated in four agro-ecological zones (AEZ) at varying elevation. Fungal communities were dominated by the Aspergillus flavus L strain morphotype (46 %), but variation occurred between years and among AEZ. 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. Insights into the dynamics and stability of aflatoxin-producing fungal communities across AEZ are discussed.