Aspergillus flavus (A. flavus) is a fungus that attacks corn and other plants and can contaminate the grain from these crops with a potentially lethal toxin called aflatoxin. Aflatoxin at low, chronic levels can cause stunted growth and impair immunity; at higher levels it can cause liver cancer or even death in humans and animals that ingest it. Once harvested, poor storage conditions of contaminated grains can lead to more aflatoxin accumulation, making the grain even more toxic and unfit to be sold on the market.
Aflatoxin is of particular concern for developing countries in Africa, as farmers and consumers are often unaware of or ill-equipped to deal with contaminated grains, and crop insurance for losses may be non-existent. The fungus, which grows better on corn plants during drought conditions, is becoming more common with the effects of climate change, such as increased temperatures and more unpredictable rainfall. Drought-stressed plants are also more susceptible to some insect pests, who can spread the fungus to other nearby plants, so a hotter and drier climate means a higher risk of aflatoxin contamination.
The good news is that some corn breeding lines are naturally resistant to A. flavus, and Feed the Future has the scientific tools to leverage this genetic advantage in the fight against aflatoxin. Researchers from the U.S. Department of Agriculture (USDA) and their collaborators are working to move protective corn genes for A. flavus resistance from naturally resistant breeding lines into new commercial corn varieties.
The challenge for researchers is that most of the corn currently grown in the world is not A. flavus resistant, so developing new breeding lines that can ward off aflatoxin even under conditions of drought will be key to making a large-scale impact on crop contamination. And despite the challenges, researchers have been able to find some promising genetic (DNA) sequences associated with increased A. flavus resistance in corn, developing a few resistant corn breeding lines that show consistent suppression of aflatoxin accumulation in many different environments.
Most of these new genetic lines are held at the USDA Corn Host Plant Resistance Research Unit in Mississippi, as well as at the International Maize and Wheat Improvement Center (CIMMYT) and the International Institute for Tropical Agriculture (IITA) in Eastern Africa. These breeding lines are being used to develop new A. flavus-resistant corn varieties that could provide a long-term solution to aflatoxin contamination in corn grain in Africa that is also easy to deploy and scale up. Today, the new crosses between resistant corn and African adapted corn varieties are being field tested to see if they can both demonstrate A. flavus resistance and thrive in Africa under potentially harsh climatic conditions.
Learn more about how Feed the Future is combating aflatoxin in Africa.