Submitted to: International Symposium of Mycotoxicology Meeting
Publication Type: Proceedings
Publication Acceptance Date: September 10, 1999
Publication Date: N/A
Technical Abstract: The objective of this study was to relate the diversity of a naturally occurring population of Aspergillus flavus to their ability to contaminate the grain with aflatoxin and produce bright greenish-yellow fluorescent (BGYF) kernels. A commercial corn hybrid (Pioneer 3394) was grown in a corn field near Kilbourne, IL, in 1996 and 1998. Twenty ears in the late milk to early dough stage of maturity were inoculated with each of 19 A. flavus strains including 16 genotypes (DNA fingerprinting), representing both aflatoxin producers and non-producers. At harvest, 20-24 kernels nearest each wounded site were separated into three categories: wound-inoculated kernels, intact BGYF kernels, and all other intact kernels. Sample weights of intact BGYF kernels in 1996 and 1998 grain samples averaged 5.0% and 9.5% of the total sample weight, respectively. Aflatoxin producing strains were associated with a higher frequency (P<0.05) of BGYF kernels for grain samples harvested in 1998. Removal of the individual wound-inoculated kernels and the intact BGYF kernels from corn ears inoculated with 13 aflatoxin- producing strains of A. flavus, lowered mean aflatoxin values from 115 ng/g (range = <1 to 387 ng/g) to 2 ng/g for 1996 grain samples and from 744 ng/g (range = 20 to 1416 ng/g) to 33 ng/g for 1998 grain samples. Results indicated substantial variation among A. flavus genotypes in their ability to produce aflatoxin in the germ and endosperm of infected BGYF kernels.