Submitted to: Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation
Publication Type: Abstract Only
Publication Acceptance Date: 10/24/2007
Publication Date: 10/24/2007
Citation: Palencia, E.R., Klich, M.A., Glenn, A.E., Bacon, C.W. 2007. Characterization of species of the Aspergillus section Nigri from corn field isolates co-infected with Aspergillus flavus/parasiticus species and the potential for ochratoxin A production.. Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation. October 22-24,2007. Atlanta, GA.
Interpretive Summary: Abstract - no summary required.
Technical Abstract: Members of the Aspergillus section Nigri, known as black-spored aspergilli, can contaminate several substrates including maize. Although some species within the group can produce plant disease symptoms such as black mold in onions and maize ear rot, the main concern with A. niger aggregate contamination is the production of a chlorinated cyclic polyketide, ochratoxin A. This mycotoxin is nephrotoxic, teratogenic, and carcinogenic to animals. The correct identification of the dark spored aspergilli is relevant since it is not clear which strains within A. niger aggregate are capable of colonizing and producing ochratoxin A on maize and maize products. However this task has been difficult because the morphology of most of the members is very similar. In order to differentiate species within this aggregate we report the use of a repetitive-sequence-based DNA fingerprinting method, the DiversiLab fingerprinting system, a barcoding procedure that looks promising. The results indicated that the corn-isolated dark-spored Aspergillus species are co-infecting sound corn kernels along with species of other Aspergillus, i.e., A. flavus/parasiticus and A. ochraceus as well as with Fusarium verticillioides. The dark spored aspergilli were present as both surface and internal infections as kernels surfaced disinfected also yielded dark spored aspergilli. Preliminary studies on the production of ochratoxin A by isolates from corn are presented. The barcoding system established that this procedure is a rapid and reasonably inexpensive procedure for identifying these fungi. Based on this brief preliminary survey, several species were found in field samples and of these, two species of this group were identified as A. carbonarius and A. foetidus, both of which are known producers of ochratoxin A.