Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/15/2006
Publication Date: 4/1/2006
Citation: Jaime-Garcia, J., Cotty, P.J. 2006. Crop rotation influences aflatoxin producing potential of Aspergillus communities in South Texas. National Cotton Council Beltwide Cotton Conference. San Antonio, TX. p. 60-63. Interpretive Summary: Aflatoxins are toxic fungal metabolites that can inhibit human development, cause cancer and even induce death. These poisons are produced by a variety of fungi. In order to develop rational tools for limiting contamination, it is necessary to identify the fungi that cause the majority of aflatoxin contamination. Recently, over a hundred deaths occurred in Kenya due to aflatoxin contamination of corn. As part of our efforts to identify the most important agents causing aflatoxin contamination, we examined the fungi causing these deadly aflatoxin outbreaks. The S strain of A. flavus, a fungus common in Texas and Arizona, was found to be the primary causative agent. This is the most compelling data to date suggesting fungal community composition, and specifically, incidence of the S strain is an important determinant of contamination. The results suggest that strategies aimed at the S strain of A. flavus may be most effective at reducing aflatoxin contamination.
Technical Abstract: Aspergillus flavus, the causal agent of aflatoxin contamination, is a natural inhabitant of soils. A. flavus can be divided into two strains, S and L, with S strain isolates having a greater aflatoxin contamination potential than L strain isolates. Aflatoxin contamination can be severe in several crops in South Texas, including cottonseed and corn. A. flavus communities in soils of South Texas cropped to cotton, corn and sorghum were studied to determine if crop rotation influences the magnitude and composition of A. flavus communities. On average, propagules/g was higher in fields where the previous crop was corn compared to either cotton or sorghum. On the other hand, fields in South Texas previously cropped with cotton had more S strain than fields previously cropped with corn. Fields previously cropped to sorghum were intermediate between those cropped to cotton and corn. Thus, in South Texas, crop rotations influence both the quantity of A. flavus in soils and the average aflatoxin producing potential of Aspergillus communities.