Preharvest Aflatoxin Contamination in Maize: Resistance and Genetics 1

Preharvest aflatoxin contamination of maize (Lea mays L.) gram by Aspergillns spp. is a concern to both producers and consumers of maize. Aflatoxms are carcinogenic to animals and have been linked to liver cancer in humans. The most desirable solution for eliminating or reducing aflatoxin contamination is to identify and/or develop sources of resistance. However, only a few genetic studies, which utilized a limited amount of genetic material, have been conducted. A thorough review and consolidation of information from these studies was deemed necessary. The purpose of this paper is to present a current, critical review on aspects of infection by Aspergillus, role of insects, inoculation techniques, and sources and genetics of resistance as they relate to aflatoxin production in maize. Damage to maize kernels by insects, especially the European corn borer (Ostrinia nubilalis Hubner), fall armyworm (Spodoptera frugiperda J. E. Smith), and corn ear-worm (Helicoverpa zea Boddie), has been associated with high aflatoxin levels. Artificial inoculation techniques that damage maize kernels generally result in the highest and most consistent aflatoxin levels. Although, a relatively large amount of maize germplasm has been screened for resistance and varying levels of resistance have been identified, additional germplasm needs to be systematically evaluated. To date, there are no known genotypes with complete resistance. Results from the few genetic studies indicated that additive genetic effects controlled resist-Preharvest aflatoxin contamination of maize (Zea mays L.) gram by Aspergillns spp. is a concern to both producers and consumers of maize. Aflatoxms are carcinogenic to animals and have been linked to liver cancer in humans. The most desirable solution for eliminating or reducing aflatoxin contamination is to identify and/or develop sources of resistance. However, only a few genetic studies, which utilized a limited amount of genetic material, have been conducted. A thorough review and consolidation of information from these studies was deemed necessary. The purpose of this paper is to present a current, critical review on aspects of infection by Aspergillus, role of insects, inoculation techniques, and sources and genetics of resistance as they relate to aflatoxin production in maize. Damage to maize kernels by insects, especially the European corn borer (Ostrinia nubilalis Hubner), fall armyworm (Spodoptera frugiperda J. E. Smith), and corn ear-worm (Helicoverpa Zea Boddie), has been associated with high aflatoxin levels. Artificial inoculation techniques that damage maize kernels generally result in the highest and most consistent aflatoxin levels. Although, a relatively large amount of maize germ-plasm has been screened for resistance and varying levels of resistance have been identified, additional germplasm needs to be systematically evaluated. To date, there are no known genotypes with complete resistance. Results from the few genetic studies indicated that additive genetic effects controlled resistance to aflatoxin contamination in maize. Aflatoxin production on maize grain appeared to be greatly influence by the environment. Further genetic studies, utilizing additional germplasm, are warranted for a better understanding of the nature of resistance to asflatoxin contamination in maize. Future research needs and plans relative to resistance to aflatoxin contaminaton in maize are presented.