Since it is unlikely that preharvest mycotoxin contamination of crops will be reduced significantly through careful cultural practices, control of these problems will likely be dependent upon the development and introduction into the commercial market, of germplasm, resistant to the growth of mycotoxi-genic species, and/or biosynthesis of toxins by these species. The identification of resistance traits in corn and other crops can, through marker-assisted breeding, facilitate a more rapid development of resistant, commercially-acceptable germ-plasm. Genetic engineering provides a tool especially useful for introducing resistance genes into crops with little natural genetic diversity (e.g., cotton), and for testing the efficacy of putative resistance genes.
Studies identifying compounds that affect mycotoxin biosynthesis offer hope to researchers. Limiting fungal growth in crops is an important aspect of host resistance, however, obtaining zero growth of fungi capable of exploiting a variety of different substrates, such as the facultative pathogen A. flavus, may be difficult to achieve. Therefore, the identification of a natural compound that blocks mycotoxin biosynthesis might be the closest we come to discovering a "magic bullet." Nevertheless, the investigations discussed in this chapter, using molecular-based technologies to identify and characterize various resistance mechanisms in crops susceptible to mycotoxin contamination, and against different mycotoxigenic fungi, are building a foundation which can lead to the implementation of a successful gene pyramiding strategy to produce mycotoxin-resistant, commercially-attractive crops.
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