Indiana University Research & Creative Activity

Food

Volume 30 Number 1
Fall 2007

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soybeans

Roger Innes
Roger Innes
Photo © Tyagan Miller

21st Century Food

by Jeremy Shere

Drive along any interstate or major highway in Indiana and you're bound to see them: fields of low, leafy soybeans stretching away on either side. Unlike corn, with its tall stalks and tufted ears, soybeans are pretty inconspicuous. They look like garden-variety weeds--boring green plants of no particular consequence.

But in fact, few plants are as important for our physical and economic well-being as soybeans. In 2006, soybeans accounted for 29 percent of U.S. crop area planted (second only to corn's 31 percent) and netted farmers nearly $20 billion in proceeds. Known as the "miracle crop," soybeans are valuable for their oil, which is used in everything from adhesives to waterproof cement. Soybean meal is a main ingredient of animal feed, soy flour is found in most baked goods, and soy hulls find their way into cereal and snack foods. In other words, much of the stuff we eat and use every day depends on soybeans in one way or another.

Anything that threatens soybean yields, then, is a problem. In 2004, that problem appeared in the form of Asian soybean rust, blown in from South America by Hurricane Ivan. The rust is a fungus that spreads quickly, and it has cost American farmers billions of dollars in reduced production and the expensive application of fungicides to curb the blight.

Most plants have some built-in resistance to disease, but so far, no known soybean varieties can resist the fungus. But just because nature hasn't produced a soybean able to stand up to the blight doesn't mean that such a plant isn't possible. Just ask Roger Innes. In 2003, Innes, a professor of biology at Indiana University Bloomington, received a $2.6 million National Science Foundation grant to study disease resistance in soybean plants--a crucial step toward isolating the genes needed to create genetically engineered soybeans able to resist Asian soybean rust.

Frankenfood or Miracle Crops?

When it comes to genetically modified, or GM, food, people tend to fall into two groups. The first group are horrified at the thought (and increasingly, the reality) of say, tomatoes genetically engineered to resist frost thanks to the addition of a gene borrowed from coldwater fish. For people alarmed by this sort of genetic manipulation, fish-enhanced tomatoes and other genetically tinkered-with crops represent scientific recklessness of the most egregious sort.

GM advocates, on the other hand, see foods such as yeast engineered to "sniff out" explosives (thanks to the addition of rat and jellyfish genes--see New Scientist magazine, May 9, 2007, for the full story) as the epitome of scientific ingenuity. If genetically modified tomatoes, corn, rice, and other crops can help feed undernourished and starving populations, that's all the more reason to hail GM crops as one of the best and most useful innovations of contemporary science.

Innes falls somewhere in between.

"Many of the common fears about genetically engineered food are based on vague suspicions instead of concrete evidence," he says. "But that doesn't mean that there aren't some legitimate concerns and problems that need to be evaluated on a case-by-case basis."

One concern about GM produce is that messing with plant genes could have long-term health consequences for people who eat them. Will eating a tomato enhanced by fish genes end up doing us harm? Maybe, but Innes thinks it's unlikely.

"As far as I'm concerned there are no legitimate health concerns with currently approved GM crops," he says. "Any genetically modified crop has to be tested for allergens. In fact, GM varieties are more highly regulated than conventional crops. So I don't know of any significant health concerns."

But what about the argument that engineered plants could crossbreed with their wild cousins, creating so-called "superweeds" and forever altering wild plant species? Innes admits that transferring engineered genes into the wild could be a concern in some cases where domesticated crops such as sunflowers have wild counterparts. But in many other cases, he says, crossbreeding is unlikely.

"In the United States, corn doesn't crossbreed with any wild species. And there are no native species that soybeans breed with, so there's really no chance in these cases of so-called contamination," he says.

In general, Innes says, claims made against GM food lack strong evidence. And meanwhile, there is substantial evidence that GM crops are good for the environment. Corn and soybeans engineered to resist the powerful Roundup herbicide, for example, mean that farmers can kill weeds with a single dose instead of saturating their fields with multiple sprayings of different toxins. Roundup breaks down quickly and binds to soil particles, and it's less likely to be siphoned off into groundwater, streams, and lakes. Similarly, crops engineered to produce their own pesticide reduce the amount of chemicals needed to ward off plant-eating pests.

"It's easy to generate fear about genetic engineering because it deals with what people eat," says Innes. "But because most people are removed from farms and don't really know anything about how food is produced, they can't really appreciate the need to change how herbicides and pesticides are used, and how genetically enhanced crops can facilitate change."

Soybeans Double Up

Innes's work on soybean disease resistance is not the stuff of major headlines. And it's not likely to draw the ire of Greenpeace, the Sierra Club, or other environmental groups that have vehemently protested GM crops around the world. For one thing, most soybean varieties grown in the United States have already been genetically altered to resist insects and some diseases (as has corn) and been proven safe for consumers.

But Innes's research is no less important for being under the media radar. If scientists are going to devise a way for soybeans to resist Asian soybean rust, they'll have to begin by digging deeper in the soybean's genetic history. Like many other plants, soybeans have the ability to crossbreed with a closely related variety. Sometimes, when that happens, the resulting offspring inherits a complete genome from each parent. Consequently, the new variety has twice as many chromosomes--40 instead of the normal 20--as its progenitors. In other words, the plant's genome is doubled.

This is precisely what happened at some point along the soybean plant's evolutionary timeline. The doubling up of the soybean genome is worth noting, Innes says, "because from an evolutionary standpoint, it gives the plant room to experiment without doing too much damage."

By "experiment," Innes means that, over millions of years, soybeans have been able to absorb potentially harmful mutations. If a particular mutation turns out to do damage, the plant always has a backup gene that can override it. Working with five other research teams around the country, Innes is interested in how the soybean's doubled genome affects its ability to resist disease.

"Does the doubling make the plant more resistant?" he asks. "Or is it a negative insofar as a surplus of disease-resisting genes may result in genes firing when they don't need to and attacking the plant's own cells?"

Innes and his collaborators are now in their fourth year of trying to answer that question. One clue, Innes says, is that genes tend to operate on a "use them or lose them" basis. When there is nothing for a gene to do, or a gene's function becomes obsolete, it's typically discarded. Innes has found that soybeans lose genes very rapidly--a sign that the doubling of its genome has probably not contributed to increasing the number of its disease-resistant genes.

The best hope for soybeans against the rust fungus, then, could lie in isolating genes from wild relatives of soybean that are known to be resistant to the disease and then inserting these genes into soybeans. Because gene locations tend to be conserved among related plant species, Innes's exploration of the inner workings of soybean genetics is helping to plant the seeds of a soybean disease solution.

Jeremy Shere is a freelance writer in Bloomington, Ind.