Crop Tech Corner

RNAi Technology Creates Aphid Insecticide, Aflatoxin-Resistant Corn

Emily Unglesbee , DTN Staff Reporter
A genetic engineering technique called RNA-interference (RNAi) shines in this week's Crop Tech Corner. (DTN photo by Nick Scalise)

ROCKVILLE, Md. (DTN) -- This bi-monthly column condenses the latest news in the field of crop technology, research and products.

A NEW KIND OF APHID REPELLENT

Illinois researchers are taking the concept of "spraying for aphids" to a whole new genetic level, according to an Illinois News Bureau press release. University of Illinois entomologist Allison Hansen and her graduate student Margaret Thairu have found a way to aerosolize RNA, the tiny genetic molecules that regulate the expression of our genes. They can be used to shut specific genes off in a target pest in a process called RNA-interference (RNAi). In the past, this has been achieved by injecting the RNA into the pest or genetically engineering a plant to produce the RNA in its tissues and then waiting for the pest to feed on it. The size of the soybean aphid (think a grain of pollen) makes both techniques extremely tedious and difficult.

So Hansen and Thairu created a spray made up of nanoparticles coated with RNA. They then blasted the unsuspecting aphids -- who hate getting wet -- to see if the insects would take up the RNA through tiny breathing tubes called tracheoles. It worked; the RNA in the spray appeared to block the targeted gene's expression and the resulting aphid adults were significantly smaller than the control aphids. The experiment was not a complete homerun; other species of aphid did not react the same way, and another RNAi spray targeting a different gene failed. But the Illinois scientists are optimistic that they have uncovered a valuable new pest control tool, particularly for small, sap-sucking insects like the aphid. "This method is going to propel our field forward, especially for insects where other techniques fall short," Hansen concluded in the news release.

See the release here: http://bit.ly/… and the researcher's study here: http://bit.ly/….

AFLATOXIN-RESISTANT CORN

In another triumph for RNAi technology, University of Arizona scientists have engineered corn plants that express RNA molecules that prevent fungi from producing aflatoxin. All corn producers -- and especially Southern growers -- struggle with aflatoxin, a dangerous toxin produced by the Aspergillus fungus. It is deadly to both livestock and humans at very low levels and can render an entire corn harvest useless.

According to a University of Arizona news release, UA plant scientist Monica Schmidt worked with a team of scientists to produce corn plants that pass RNA from their kernels into the Aspergillus fungus when the plant is infected. Once in the fungus, the RNA targets a gene that produces an enzyme that is key to the toxin production. The RNA switches the gene off, and although the Aspergillus fungus continues to grow, it produces no aflatoxin.

The scientists did extensive testing to ensure that the GMO corn plants didn't produce any undesirable side effects. "This corn plant would be like any other," Schmidt said in the news release. "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."

See the news release here: http://bit.ly/… and the scientists' study here: http://bit.ly/….

A BETTER GENE EDITING TOOL FOR AGRICULTURE

CRISPR-Cas9, a fast-developing gene editing technology, has taken the world of genetics and breeding by storm. The technique allows scientists to cut and paste genes in and out of the DNA of plants, animals and even humans. However, gene editing with CRISPR is not always perfectly precise, and the potential for mistakes to slip into the targeted genome remains a concern. Now, a University of Maryland scientist has fine-tuned a version of CRISPR specifically for use in plants, with a great improvement in accuracy, according to a UMD news release. UMD plant scientist Yiping Qi tinkered with a CRISPR version called CRISPR-Cpf1 and incorporated a specific RNA molecule that can act as an enzyme. Using this new method, Qi and his team of researchers were able to produce 100% of the desired targeted gene changes in a transgenic rice crop. "This represents a new and cost-effective breeding tool that will help generate elite plant varieties in agriculture within a few generations," the UMD release concluded.

See the press release here: http://bit.ly/… and Qi's study here: http://go.nature.com/….

Emily Unglesbee can be reached at emily.unglesbee@dtn.com.

Follow Emily Unglesbee on Twitter @Emily_Unglesbee.

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