ARS | Publication request: Evaluation of the Contribution of Intact Seed Coats Versus Internal Mechanisms of Corn Kernel Resistance to Aspergillus Colonization and Aflatoxin Production

Submitted to: Aflatoxin Workshop
Publication Type: Abstract
Publication Acceptance Date: October 25, 2002
Publication Date: N/A

Technical Abstract: The objective of this experiment was to evaluate maize resistance to Aspergillus flavus infection and aflatoxin contamination in undamaged grain from wound-inoculated ears. Several inbreds and F1 crosses with demonstrated resistance or susceptibility to aflatoxin, as determined by the pinboard inoculation method, were further evaluated using the `punch-drill and pipe-cleaner' method of wound-inoculation. At harvest, 20 to 24 non-damaged kernels surrounding each wound-site are removed from the ear and examined for bright greenish yellow fluorescent (BGYF) kernels and aflatoxins. The method emphasizes kernel resistance to the parasitic abilities of the fungus and is based upon the occurrence of BGYF kernels and the extent to which these kernels become contaminated with aflatoxin. FR1064 x Mp313E, FR1064 x Oh516 and Oh516 had no BGYF kernels in the undamaged grain near points of wound-inoculation and recorded the lowest aflatoxin levels among all genotypes. However, BGYF kernels with substantial aflatoxin contamination were recovered in the other grain on these ears indicating that the individual kernels were not immune to A. flavus or aflatoxin. The F1 crosses FR1064 x MP313; FR4310 x MP313; FR4310 x MP420 were shown to offer a source of internal grain resistance to A. flavus and aflatoxin. The aflatoxin resistance demonstrated for these genotypes can be attributed to inbred parents that resist seed coat tearing or provide internal sources of kernel resistance. None of the F1 crosses we examined combined these resistance phenotypes.