Mycotoxins are considered to be among the most significant food contaminants because of their negative impact on public health, food security, and the national economy of many countries. They affect a wide range of agricultural products, including cereals, nuts, and oilseeds, that are used for human food and animal feeds. Mycotoxin contamination of susceptible commodities occurs as a result of environmental conditions in the field as well as improper harvesting, storage, and processing operations [1–3]. Mycotoxins may be carcinogenic, mutagenic, teratogenic, and immunosuppressive. Estimated annual losses in the USA and Canada arising from the impact of mycotoxins on the feed and livestock industries are of the order of $5 billion. In developing countries, food staples are susceptible to contamination and it is likely that a significant number of human deaths are attributable to the consumption of mycotoxins .
Aflatoxins are an important group of mycotoxins that are produced as secondary metabolites under conducive climatic conditions by the fungi Aspergillus flavus Link:Fr. and A. parasiticus Speare . The most common aflatoxins produced by these fungi are B1, B2, G1, and G2; the most potent of these is B1 [4, 5]. Because aflatoxin induces animal diseases, particularly liver cancer in humans, aflatoxins are the most widely studied mycotoxins. More than 50 countries have established or proposed regulations for controlling aflatoxin ingestion from contaminated foods and feeds [6–9]. The U.S. Food and Drug Administration  set a tolerance level of 20 ng g-1 for aflatoxin B1 in maize (Zea mays L.). Grain that exceeds that level cannot be shipped via interstate commerce or used for human consumption. As of 2003, 61 countries have imposed regulations on aflatoxin B1 levels in foodstuffs . Aflatoxin contamination of corn reached epidemic proportions in the U.S. in 1977 and 1998. In 1998, aflatoxin contamination resulted in $85 to $100 million in losses to maize producers in Texas, Louisiana, and Mississippi , and the combined crop loss due to aflatoxin epidemics in the southern USA during 1988, 1989, 1995, 1996, and 1998 surpassed $1 billion . Because A. flavus infection and aflatoxin accumulation can lead to substantial economic losses and risk to human and animal health, efforts to create resistant corn varieties are ongoing. The seriousness of the problem of aflatoxin has generated large quantities of data from many breeding and genetics, fungal biology, physiological and biochemical studies, but the problem has yet to be solved.
Genetics and breeding studies have focused on identifying lines with genetic resistance, either to fungal infection or specifically to aflatoxin accumulation [14–16], and mapping the resistance genes and moving them into susceptible corn inbred lines. Biochemical studies have worked to identify the aflatoxin toxicity pathways and determine its effects on the physiology of the animals that eat infected grain and ways to mitigate these effects [4, 5]. Genomics and proteomics studies of both the fungus and the corn plant, seek to identify pathways, proteins, and genes involved in toxin metabolism and catabolism, to manipulate the production and reduction of aflatoxin and keep levels low in fungal-infected grains. Finally, many studies of resistance mechanisms to fungal infection and spread in plants are available, and much of this research may shed some light on the search for genes conferring resistance to A. flavus.
The Corn Fungal Resistance Associated Sequences Database (CFRAS-DB) was created to integrate different data types from studies of aflatoxin resistance in maize by different researchers to allow us to more effectively investigate mechanisms, pathways, and genes that confer resistance to some maize lines, and allow the development of high yielding maize lines with resistance to A. flavus and/or aflatoxin. CFRAS-DB uses a MySQL relational database management system with dynamic query and data integration to help researchers identify gene sequences with a possible role in aflatoxin accumulation resistance, using multiple lines of evidence. This may help narrow the number of potential candidate genes that will be studied to determine or confirm function in aflatoxin accumulation resistance in maize. Genes with the highest probability of being associated with aflatoxin accumulation resistance should be given priority for further study, including the creation of transgenic plants to test construct effect, association analysis of candidate genes with important phenotypes, or other biochemical or genetic tests of gene function.
One of the major challenges of integrating data from different types of experiments conducted by different researchers over several different years is mapping the identifiers used in the different studies to a common set of identifiers. MaizeSequence.org is a central resource for the recently sequenced maize genome and we use their gene model identifiers as reference identifiers. Sequences from all experiments stored in CFRAS-DB are mapped to MaizeSequence.org sequences and the MaizeSequence identifiers serve as the primary key linking the different experiments. Data entries may represent DNA sequences, protein sequences, genetic loci (locations) on a chromosome, expression data of specific proteins or RNA sequences, or physiological or phenotypic traits linked to genetic markers at known loci. This database supports multiple dynamic queries to find and display data for different genes and genotypes (individual maize plants). The outputs based on these queries can also be downloaded and used as input for pathway analysis programs for more evidence of a common function for genes these queries identify.