Submitted to: Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation
Publication Type: Abstract only
Publication Acceptance Date: 10/7/2004
Publication Date: 3/1/2005
Citation: Chang, P.-K., Horn, B.W., Dorner, J.W. 2005. Deletions in the aflatoxin biosynthetic gene cluster of nonaflatoxigenic and cyclopiazonic acid-nonprodicing Aspergillus flavus isolates. In: Proceedings of 2004 Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop, October 25-28, 2004, Sacramento, CA. p. 79. Interpretive Summary:
Technical Abstract: Aflatoxins (AF) and cyclopiazonic acid (CPA) commonly contaminate agricultural commodities. Subpopulations of Aspergillus flavus that produce either, neither, or both toxins are present in agricultural soils of several Southern states. We examined the aflatoxin biosynthetic gene cluster of 24 AF-negative and CPA-negative A. flavus isolates, which belong to various vegetative compatibility groups. Five of those A. flavus strains have a partial deletion in the aflatoxin gene cluster, and 18 have completely lost the aflatoxin gene cluster. Using PCR, we detected two different breakpoints, at one end of the aflatoxin gene cluster, responsible for the partial deletions. One is between norA and ver1, and the other between ver1 and omtB. A breakpoint responsible for the complete loss of the aflatoxin gene cluster was located between hexA and glcA of the sugar utilization gene cluster, which resides downstream of the aflatoxin gene cluster. For these 22 A. flavus strains, the breakpoint at the other end lies beyond 10 kb of the aflatoxin gene cluster. In contrast to AF-negative and CPA-positive A. flavus isolates, deletions of the aflatoxin gene cluster appear to be prevalent only among AF-negative and CPA-negative A. flavus isolates.