ARS | Publication request: MOLECULAR ASPECTS OF CORN RESISTANCE MECHANISMS AGAINST AFLATOXIGENIC FUNGI

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 15, 2004
Publication Date: June 30, 2005
Citation: Brown, R.L., Chen, Z.-Y., Cleveland, T.E., Bhatnagar, D. 2005. Molecular aspects of corn resistance mechanisms against aflatoxigenic fungi. In: Thangdunai, D., Pullaiah, T., Balatti, P.A., editors. Genetic Resources and Biotechnology. v. 2. New Delhi, India: Regency Publications. p. 281-294.

Technical Abstract: Aflatoxins are fungal metabolites of the fungi Aspergillus flavus and A. parasiticus that can contaminate foods and feeds after infection and exhibit toxic and carcinogenic effects in higher organisms that consume the contaminated commodities. Corn, cottonseed, peanuts, and tree nuts are economically important crops seriously affected by aflatoxin contamination. The purpose of this review is to highlight scientific advances in the development of host plant resistance against aflatoxigenic fungi, as a result of discoveries of resistance traits 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 A. flavus strains genetically transformed with reporter gene constructs for dual assessment of fungal growth or aflatoxin pathway gene activities aflatoxin production. Kernel proteins, both constitutive and induced, have been implicated in resistance. Proteins have been identified that are bioactive against A. 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 development of near-isogenic corn lines varying in aflatoxin accumulation. Natural compounds in corn inhibitory to aflatoxin 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 may enable host targeting of specific fungal toxigenic mechanisms and fungal virulence mechanisms as well.