RNAi Technology Alters Crops in Field

December 5, 2015 02:52 AM

A new tool in the fight against pests, diseases, weeds and drought

As a young boy weeding on his family’s southwest Louisiana rice farm in 1960, John Killmer was startled to see a airplane cross over his field. His father identified it as a crop duster passing to spray a neighbor’s weeds. A year later, the Killmer farm was also using airplanes to spray weeds. The leap from hand-weeding to aerial herbicide application had a tremendous impact on Killmer, who is now on the frontlines of a major change in farming technology. 

The advent of ribonucleic acid interference (RNAi)—a sniper’s bullet technology—has implications for every aspect of crop growth. Diseases, drought, pests and much more are in the crosshairs, and the possibilities for this non-GMO crop alternating technology seem boundless.

Think of RNAi as a covert operator: It slips in, temporarily shuts down a gene and is gone. Got an insect flare-up in corn? Reach into the arsenal and feed the pests a gene-specific RNAi that shuts down their digestive tracts. The pests die; the crop thrives; no genetic modification required. 

RNA is a template produced from DNA and used to make protein. A tiny piece of RNA interferes with the template-building process. 

“Some believe the alterations can be as powerful as GMO systems now in use,” says Killmer, CEO of APSE, a company specializing in technology to create bulk RNA. “The RNAi concept most often tossed around is drought resistance. Plant a normal crop variety, and if drought shows up, apply an RNAi that alters crops during drought.”

Essentially, RNAi is a non-GMO “as needed” path to crop traits. GMO modifications are heritable, but RNAi application is a one-shot, knock-down effect that isn’t passed on to progeny. 

“In insects, there is just enough temporary interference to keep the organisms from surviving,” says Meg Allen, research entomologist, Biological Control of Pests Research Unit, Stoneville, Miss.

The potential for RNAi applications span from flavor and plant growth to pests and weed control. RNA is an extremely fragile molecule, though, so it’s challenging to deliver RNAi into plants across a field. 

Killmer believes early RNAi uses will be commercialized to bypass delivery obstacles. As a topical treatment, application could be made by airplane, sprayer or seed treatment. 

“If you can deliver non-degraded, double-stranded RNA to a pest and it matches a gene the pest needs to survive, the pest will become sick or die,” Allen says. “The DNA code is so specific, the likelihood of RNAi affecting anything but the pest it’s designed for is extremely low.” 

RNA is found everywhere. A person typically consumes a gram of RNA in fruit, vegetables, grain and meat each day. The Environmental Protection Agency is looking at regulatory RNAi issues and off-target effects. 

Along with delivery challenges, RNAi production costs are a major hurdle. Although RNAi is effective at a low dose—grams per acre—early RNAis cost hundreds of thousands of dollars per gram, Killmer says. APSE is focused on bringing down RNA costs and maintaining stability of RNA on the leaf and seed. As interest grows and investment builds, the dollar amount has dropped to produce RNAi. APSE is targeting a $2 per gram price tag, a seismic shift. 

By 2020, Killmer thinks RNAi will be available as a spray-on for insect control. “It’s no understatement to say RNAi could impact every part of a farmer’s crop production process.” 

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