Submitted to: Corn Dry Milling Conference Proceedings
Publication Type: Review Article
Publication Acceptance Date: 5/29/1997
Publication Date: N/A
Technical Abstract: The present emphasis of research to control A. flavus and aflatoxin in preharvest corn involves the identification of relevant resistance factors and their transfer into commercial hybrids. Reliable inoculation techniques have been developed to screen corn germplasm for resistance to A. flavus and aflatoxin. Molecular marker mapping (RFLP) of genes for resistance to A. flavus infection and/or aflatoxin is presently guiding efforts of corn geneticists to determine the inheritance of resistance. Natural mechanisms of kernel protection against A. flavus or aflatoxin have been identified and are currently being investigated: (1) intact seed coats resistant to tearing; (2) pericarp wax layer thickness; (3) pericarp browning wound defense reaction associated with peroxidase isozymes; (4) anthocyanin aglycones - pelargonidin, cyanidin, etc; (5) carotenoids - alpha carotene, lutein, etc., inhibit aflatoxin biosynthesis early in the pathway; (6) antifungal inhibitory protein from the inbred Tex 6; (7) germination induced resistance factors-- Zeamatin antifungal protein & RIP (ribosome inactivating protein). Bioactive proteins from other organisms have been identified which inhibit A. flavus growth in vitro including Cercropin B, an antifungal peptide from the giant silk worm moth, and soybean lipoxygenase, involved in the generation of antifungal volatiles which inhibit A. flavus spore germination or compounds that interfere with aflatoxin biosynthesis genes. Proprietary technologies involving the transformation of corn with genes encoding antifungal peptides invites collaborative research between ARS and biotechnologists in corn seed producing companies.