Preharvest host resistance is a widely explored strategy for combatting fungal attack. By far, most studies aimed at the incorporation of antifungal resistance against mycotoxigenic fungi have been applied toward improvement of resistance against preharvest aflatoxin contamination in corn [reviewed in Brown et al. (1998)]. With corn, the strategy of enhancing host resistance to aflatoxin contamination through breeding has gained prominence because of: (a) the successful identification of germplasm resistant to aflatoxin contamination [reviewed in Brown et al. (1999)] and (b) the significant advances in the identification of natural resistance mechanisms and traits (Brown et al. 1998; 1999; Chen et al. 2001). However, these investigations indicated that resistance to aflatoxin contamination involves multiple chromosome regions and several genes (Davis and Williams 1999). Therefore, attempts to select for resistance traits in the development of commercial corn varieties, while maintaining desirable agronomic characteristics, have been slowed due to a failure to identify expressed genes and proteins involved in resistance. This is especially needed since resistance, thus far identified is in poor genetic backgrounds. Therefore, research is needed to elucidate the biochemical mechanisms that confer resistance in corn kernels and other crops that are vulnerable to aflatoxin contamination. These resistance mechanisms could then be used to enhance germplasm through marker-assisted breeding and/or genetic engineering, two methods for employing the identified traits towards the development of resistant commercially-acceptable crops (Brown et al. 1999). Gaining an understanding of the natural resistance mechanisms in corn could serve as "nature's lesson" about the specific requirements for seed-based resistance against fungal attack. This information will help efforts to incorporate and enhance resistance in other crops vulnerable to aflatoxin contamination such as cottonseed, peanut, and tree nuts, and will perhaps even help efforts to enhance resistance against other groups of mycotoxigenic fungi.
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