Submitted to: Meeting Abstract
Publication Type: Abstract Only
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. Nineteen strains of A. flavus isolated from a corn field near Kilbourne, IL, were used as inoculum, including 16 genotypes (DNA fingerprinting), and representing both aflatoxin producers and non-producers. A commercial corn hybrid (Pioneer 3394) was grown in this field in 1996 and 1998, and 20 ears in the late-milk- to-early-dough stage of maturity were inoculated with each A. flavus strain using a toothpick wound procedure. 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 and non- producing strains produced equivalent numbers of BGYF kernels. 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/kg (range = <1 to 387 ng/kg) to 2 ng/kg for 1996 grain samples and from 744 ng/kg (range = 20 to 1416 ng/kg) to 33 ng/kg 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.