Submitted to: Book Chapter
Publication Type: Review Article
Publication Acceptance Date: 4/1/2004
Publication Date: 7/1/2004
Citation: Brown, R.L., Chen, Z.-Y., Gembeh, S.V., Cleveland, T.E., Bhatnagar, D., Howard, K. 2004. Identification of natural resistance in corn against mycotoxin-producing fungi. In: Mohan, R.M. (editor). Research Advances in Food Science. Kerala, India: Global Research Network. p. 85-96.
Technical Abstract: Mycotoxins are fungal metabolites that can contaminate foods and feeds and exhibit toxic effects in higher organisms that consume the contaminated commodities. There are several mycotoxins of concern in food and feed safety, of which aflatoxins are the most regulated and widely investigated. The purpose of this review is to highlight scientific advances in the development of host plant resistance especially against aflatoxigenic fungi, as a result of discoveries of natural resistance in corn. Advances made in screening techniques have resulted in the identification of aflatoxin-resistant lines, as well as the discovery of mechanisms of resistance. New techniques covering both field and lab investigations are being utilized, as are fungal tester strains genetically modified with reporter gene constructs to facilitate assessments of fungal growth or aflatoxin pathway gene activities along with the quantification of aflatoxin. Kernel proteins, both constitutive and induced, have been implicated in resistance. Proteins have been identified that are bioactive against Aspergillus flavus. These investigations have been greatly advanced by the employment of proteomics, resulting in the identification of stress-related proteins associated with resistance. The identification of resistance-associated proteins (RAPs) has also been enhanced by the discovery of near-isogenic corn lines among progeny generated in crosses between resistant lines of West African and of U.S. origin. Natural compounds in corn inhibitory to mycotoxin biosynthesis have also been identified. Molecular breeding strategies appear to be the best method of transferring resistance to commercially-viable corn germplasm. Plant transformation may facilitate the enhancement of mycotoxin-resistance in other species through the incorporation of corn genes. Genomic exploitation of the A. flavus aflatoxin biosynthetic pathway, recently characterized, may present the possibility of host targeting of specific fungal toxigenic mechanisms; genomics may facilitate targeting of fungal virulence mechanisms as well.