Reducing the Fungus, Protecting the Harvest

Crops all over the world are susceptible to infection by Aspergillus fungi. This fungus produces aflatoxins, which stunt children’s growth, increases risk of liver cancer, and makes people more prone to diseases like HIV and malaria. In the U.S., crops are tested for aflatoxin and burned if levels are over 20 parts per billion. There is no testing in many developing countries, where toxin levels have been measured up to 100,000 parts per billion. Researchers at the University of Arizona have discovered a promising way to prevent the loss of crops to this fungus each year and maintain a safe food supply.

In the study, researchers infected corn plants with Aspergillus and let them grow one month. Untreated plants had toxin levels from 1,000 to 10,000 per billion. The results, published in Science Advances, show how using transgenic corn plants produce RNA molecules that prevent fungi from producing aflatoxin, suppressing the toxin levels below detectable limits. The approach is called Host-Induced Gene Silencing (HIGS).

The modified corn plants exchange RNA from the kernels to the fungus. Once inside the fungal cells, the RNA pair with the fungus’ RNA for an enzyme needed to produce toxin in a process called RNA interference, shutting off toxin production. The fungus continues to grow on the corn, but remains harmless. There was no difference in the gene expression between the transgenic and non-transgenic kernels, other than the ability to shut down toxin production. This is the first way shown to protect crops from fungus while growing in the field, rather than only after harvest and during storage.

Other methods to curb the toxin include spraying crops with Aspergillus strains that do not produce aflatoxin and breeding corn with antifungal proteins, which have had limited success. The HIGS approach holds great promise and a patent has been filed. The results of the study are accessible online so that any developing country with internet can have access to them.
Stolte, Daniel. “Small Molecule Could Play Role in Food Security.” UANews, 10 Mar 2017. Web. 16 Mar 2017.

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