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United States Department of Agriculture

Agricultural Research Service

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Aflatoxin fungus can destroy an entire corn crop, and make people very sick

 

Control and Prevention of Aflatoxin

Aflatoxin is a poison produced by a variety of common fungus species called Aspergillus, which grows on food either still growing in the field, or while in storage (post-harvest). If animals are fed contaminated grain, the toxin can be passed through their milk. Aflatoxin is dangerous to humans, and known to damage the liver, and cause cancer. It is especially toxic to children, and chronic low-level exposure can cause developmental impairment and stunting. This is a common problem in developing countries. Fungus is opportunistic, and it thrives in damp environments, and loves to attack damaged or decaying plants and food stocks.

A combined USAID/USDA working group was formed to develop the Post-Harvest Component of the Norman Borlaug Cooperative Research Initiative (NBCRI) program, which looks at aflatoxin. The group agreed “aflatoxin control” should be front and center as a proposed researchable and fundable area because a critical mass is developing to tackle the problem, evidenced by an Africa-led, ‘Partnership to Control Aflatoxin in Africa’ (PACA) recently formed, and approved under CADDP, and enjoying funding from a wide range of donors such as BMGF, USAID, AusAid, EU Aid, etc.

Scientists have found there are some strains of Aspergillus that are ‘atoxogenic’ which means they cannot produce the poison. Researchers showed that by introducing atoxogenic strains into food growth or storage environments where fungus likes to grow; allows the atoxogenic strains to overpower the toxic strains, rendering the fungus growth safe. This is called, ‘competitive exclusion’. PACA has used competitive exclusion successfully in Africa, and it is the cornerstone of their work with ARS scientist Peter Cotty of the ARS Food and Feed Safety Research Lab.

Another approach is to breed plants that can resist the fungus growth. To do this, researchers must first identify plants that are resistant, and find the genes involved so they can be used in plant breeding programs. Researchers in Mississippi are developing germplasm with partial aflotoxin resistance to develop commercial corn hybrids. Part of this work includes mapping the corn genome of these resistant plants to identify key genetic markers for resistance. These markers can be used to develop tests for resistance that will speed plant selection for new resistant variety breeding programs. The genetic work is led by scientist Marilyn Warburton of Mississippi State Corn Host Plant Resistance Research group, and in cooperation with partners from CIMMYT and IITA.

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Last Modified: 7/23/2014