One in nine people around the world battle hunger every day, so efficient and safe food production is a scientific and humanitarian endeavor of high priority. A team of University of Arizona researchers has contributed to this by developing a transgenic corn plant that can safely stave off the effects of a particularly dangerous strain of fungi.
The study, published in Science Advances, describes a new approach to fighting aflatoxins, a toxic substance produced by the Aspergillus fungi, which can spoil an entire harvest. The toxins are not deadly to humans but they have been implicated in stunting growth in children, increasing risk of liver cancer, and making people more susceptible to certain diseases such as HIV and malaria.
"Aflatoxin is one of the most potent toxins on the planet. Usually, it won't kill a person outright, but it can make you very sick," team leader and senior author Monica Schmidt said in a statement.
The researchers managed to tweak a naturally occurring mechanism to significantly reduce the amount of aflatoxins produced by the fungi. Based on previous research, they knew that during infection the host plant and the fungus would exchange RNA, a copy of the DNA used by cells to make proteins, and wondered if they could use this against the invasive fungus.
"When I read about this in the literature, I thought, 'Why can't we make a Trojan horse to shut off that toxin?'" explained Schmidt. "We introduced an engineered DNA construct into the corn that passes the RNA into the fungus when it infects the corn plant."
The approach, called Host-Induced Gene Silencing, has the modified kernels produce short RNA molecules, only in the edible kernels, so it doesn’t affect the corn plant. When the fungus attaches itself onto the kernel, the RNA moves into the fungus where it is activated. There it targets the enzyme that produces aflatoxins and shuts the production down.
In the research, which is funded by the Bill and Melinda Gates Foundation, the team showed that the amount of aflatoxins in genetically modified plants dropped below detectable level and that the GM plants had no other unusual gene expression.
"This corn plant would be like any other. The only trait that sets it apart is its ability to shut down the toxin production. It shouldn't have any other effects, but obviously, a lot of downstream testing will be required before it could be grown in the fields," Schmidt stated.
In the US, where it’s regularly tested, corn batches are destroyed if they show more than 20 parts per billion of aflatoxins. The testing doesn’t happen in many developing countries, however, and the team report levels of 100,000 parts per billion found – dangerously high for human consumption, but often the only alternative to starvation.