Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2000
Publication Date: N/A
Technical Abstract: Aspergillus flavus isolates transformed with the Escherichia coli GUS reporter gene were used to monitor fungal spread in developing corn ears. One of the isolates (GAP 2-4) was used to localize the fungus and the other isolate (GAP 26) was used to localize aflatoxin production. Ears of resistant and susceptible corn hybrids were inoculated with the GUS isolates 14 days after pollination using a modified pinbar technique. Ears were harvested at 7-day intervals until the end of the growing season. Histochemical staining was used to monitor fungal growth in kernels and cob tissues. GUS activity designating fungal presence in kernels was exclusively in the embryos. GUS activity was found more often and was much higher in susceptible cobs than in resistant cobs. Most of the GUS activity was limited to the vascular tissue of the cob. High levels of GUS activity designating aflatoxin biosynthesis were found in cobs 28 days after inoculation. High levels of GUS activity were also found at 49 and 56 days after inoculation. GUS activity designating aflatoxin biosynthesis was most commonly found in cob vascular tissue.