Jointed goatgrass is even worse than it sounds. Classified as a noxious weed in Washington state, it’s considered a threat to the state’s wheat industry, the fourth-largest in the U.S. As the regional Noxious Weed Control Board explains, the wild grass, which is a cousin of domesticated wheat, can hybridize with winter wheat, reducing yields.
But jointed goatgrass is resistant to stripe rust, a bacterial infection that’s the scourge of grain growers. In 2012, the fungus accounted for $500 million in crop loses for U.S. wheat farmers.
Thanks to new research conducted at Washington State University, the noxious weed is now being looked at as a potential boon to the wheat industry. In a study published in the Proceedings of the National Academy of Sciences, WSU researchers say they’ve discovered the gene that makes it difficult to beneficially cross wheat with related wild grasses. This advance, combined with the knowledge of how to selectively silence it, means it is now possible to make targeted crosses between wheat and related species. So you can get a wheat variety resistant to rust without the reduced yield that would come from introducing all of jointed goatgrass’ chromosomes, along with the hundreds of thousands of other genes that come with it, into wheat. As the authors write in the paper, “molecular characterization of this gene will make it possible to develop precise alien introgression strategies,” which is a wonderful bit of jargon saying they will be able to transfer only the genes they want instead of gambling on the entire mixed bag.
The promise, then, is of wheat varieties with the kind of precision-targeted improvements seen in GMO crops but without the creepiness of introducing an unrelated species into the crop. Still, said Kulvinder Gill, one of the authors of the study, a bit more genetic engineering will be necessary before we can arrive at that point. While what the researchers propose isn’t splicing a gene from one species into another, bypassing natural breeding, the new wheat variety they’re developing is assisted by some biotechnology that would be at home in a Monsanto laboratory—but it results in non-GMO seed.
Wheat is itself a cross between three different species, and its complex hexaploid genetic structure—six sets of chromosomes—has built-in protections. “Once you get a good complex of genes that gives you a Ferrari, you aren’t going to mess it up,” says Perry Gustafson, a professor at the University of Missouri and a visiting scientist at the International Maize and Wheat Improvement Center in Mexico City. That’s what the Ph1 gene identified by the WSU researches does—it’s the LoJack (to extend Gustafson’s metaphor) that attempts to block other plants’ chromosomes from throwing off the bundle of genes we’ve known as wheat for the last 10,000 years.
Breeders have been successfully crossing wheat with wild relatives since the 1940s. As Harold Bockelman, who helps manage the USDA’s Small Grains and Potato Germplasm Research Unit, which maintains a seed bank in Aberdeen, Idaho, says he receives plenty of requests for seeds from scientists working on such crosses between wild crop relatives: “There’s a general trend in that direction and utilizing them to improve productivity and disease resistance.”
But as Gustafson explains, “there’s only a certain number of close relatives that can have sex,” which is what plant breeding is at the end of the day. “If you get species that are too far apart, it won’t work." Even when crosses are successful, Gustafson says, the resulting hybrid is like a mule—productive in its own life but sterile. (There’s a chemical treatment that can turn a sterile hybrid into a fertile one, but it isn’t always effective and requires an extra step when developing a new variety.)
By employing a bit of biotech work—specifically, a process call RNA interference, which earned the scientists who discovered it a Nobel Prize in 2006—when breeding wheat with a wild relative like jointed goatgrass, the WSU team can make wider, more targeted crosses. This allows them to reach farther afield from wheat and its closest cousins to find specific traits that increase yields and resist disease.
Here’s how it works. A synthetic RNA cell genetically engineered to match the natural cell responsible for communicating with the Ph1 gene (the one that blocks those alien chromosomes) is introduced into a wheat cell. The two matching RNAs, synthetic and natural, combine, creating a double-strand cell. The chromosome-blocking Ph1 gene, which is accustomed to receiving its marching orders from a single-strand RNA, doesn’t receive its usual cue to do its job, allowing a cross to be made without interference.
There’s a second way of silencing the gene that Gill described that uses a natural wheat virus. But to use it for a targeted cross, the virus would need to be modified to carry the specific genes from another grass associated with the desired trait.
While the jointed goatgrass genes are catching a biotech ride into the wheat, it’s vital to both the process and the new variety’s commercial prospects—the international market many U.S. farmers rely on has strongly resisted GMO wheat—that the plant be non-GMO. As Gill explains, “we’re going to temporarily silence this gene when we have an alien chromosome in the wheat cell” and then turn the gene back on so it will continue to protect that (slightly updated) Ferrari.
If the synthetic RNA hangs around, Gill says, “that plant will never be normal and fertile.” While genetic engineering is integral to the process, if the final product remains a genetically modified organism, it will fail both biologically and commercially.
Gustafson didn’t want to comment too directly on the study, but he’s certain that it will spark plenty of debate among wheat breeders. Regarding this RNA interference process or any other means of speeding up evolution, he “would evaluate and use whatever technology that is safe to use and can produce a higher yield that would benefit food production on the world scale.”
“You can’t ignore technology,” Gustafson says, “but you can’t blindly accept it.”
This September, Pivot TV will feature an entire month of “Food for Thought” programming to explore what’s really happening in the American agriculture system. For more information, head over to the “Food for Thought” page to find out when the next program airs and take action.