by Phil Berger

What is agricultural biotechnology? Is it good or bad? Is it dangerous or will it relieve food shortages or malnutrition worldwide? The answers to these questions very much depend on who you ask. The debate has left the realm of scientific hypothesis testing and has arrived as a major social, political, and economic hot potato.

Left: Phil Berger is a professor and chair of the Plant Pathology Division of the UI Department of Plant, Soil, and Entomological Sciences. Phil Berger photo by Michele Kimberling, UI Photographic Services

In 1987, the first U.S. field-based tests of a genetically modified crop were conducted. Since then, there have been over 6,000 such tests. Virtually every major crop grown in the world and many minor ones have been genetically engineered for at least one new trait. In 1999, there were about 70 million acres of genetically modified crops grown, the most common of these being soybean, corn, cotton, and canola. The vast majority of these crops were either herbicide tolerant or insect resistant.

Agricultural biotechnology has been adequately defined by the U.S. Department of Agriculture (USDA) as "the use of biological processes of microbes, and of plants or animal cells for the benefit of humans…a collection of scientific techniques, including genetic engineering, that are used to create, improve, or modify plants, animals, and microorganisms." These modifications, called GMOs (for genetically modified organisms) or GM (genetically modified) crops, have resulted in maize that is resistant to European corn borer, cotton that is resistant to several lepidopteran insects, soybeans that are resistant to glyphosate (Roundup™), virus-resistant papaya, and many other modifications.

We now know how to insert foreign genes into most crop plants and to allow these new genes to be integrated and inherited by subsequent generations of the crop. Thus, an almost infinite number of new genes can be utilized for crop improvements, including pest or pathogen resistance and improvement of agronomic properties and nutritional content. GMOs may even be able to produce valuable pharmaceuticals, vaccines, and specialty chemicals.

However, many people are afraid or distrustful of this technology. Considering that this new technology directly impacts our food supply, this is perhaps not surprising. GM crops are currently regulated in the U.S. by as many as three federal agencies, depending on the nature of the crop modification. The USDA (specifically the Animal and Plant Health Inspection Service, or APHIS) has the authority to regulate the introduction, interstate movement, and release into the environment of any GM crop. APHIS also has the authority to determine that a release is safe and will not harm native plants or organisms.

If the GM crop is classified as a ‘"pesticide" or pesticidal, as is the case with Bt maize and cotton, then the U.S. Environmental Protection Agency (EPA) has the authority to regulate the use of the crop under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food Drug, and Cosmetic Act (FFDCA). These crops are evaluated for such things as effects on non-target organisms, environmental fate, and residue toxicology.

The U.S. Food and Drug Administration (FDA) has authority, also under the auspices of the FFDCA, to ensure that all foods for human consumption are safe, whether they are domestic or imported. Foods from GM crops are evaluated, and if differences from the non-GM equivalent are noted, then the GM crop must be tested further for content, allergenicity, and toxicity.

Regardless of how individuals feel about the use of agricultural biotechnology, it is important that we make decisions based on fact and not on rhetoric or misinformation. There are several issues surrounding the use of GM crops that are central to the current debate.

Risk 1

Insects may develop resistance to pesticide-producing plants.

Facts:

This is indeed possible. It depends on many factors, such as the mode of action of the pesticide and the level of selection pressure on the insects. This is a particular fear of organic growers, since "natural" pesticides such as the toxins produced by the bacterium Bacillus thuringiensis (Bt), contained in products such as Dipel, are among the few treatments available for insect control in organic crops.

Information:

While the long-term effectiveness of these products is still under investigation, commercial producers of Bt-containing crops must follow certain guidelines for crop production and management. These guidelines are based on the best science available, and are intended to reduce the risk of target insects developing resistance to the pesticides.

Risk 2

Herbicide-tolerant crops could cross-pollinate weeds, resulting in "superweeds."

Facts:

This is a possibility. It greatly depends on the particular crop, however. So far, there is little evidence that this has actually occurred in nature. It is possible that gene transfer could occur if weeds with which the crop can cross-pollinate grow in proximity to a crop genetically engineered for herbicide resistance. While there are wild relatives of maize and soybeans, these species do not grow in the Midwest U.S. and there is virtually no chance of cross-pollination.

On the other hand, there are weed relatives of wheat, canola, and oilseed rape that could conceivably cross with these crops, possibly resulting in herbicide-tolerant weeds. Research at UI has been done to determine the potential for interspecific crossing between canola and its weedy relatives as well as between wheat and its weedy relative, jointed goatgrass. Both projects have shown that the potential does exist for gene flow between the crop and weedy relatives. Research is currently underway to determine if location of the gene in these crops could minimize the potential for gene movement. Results of this research will be used to develop crop management strategies that maximize the longevity and effectiveness of the herbicide resistance as a tool to control weeds while minimizing the transfer or development of herbicide resistance in the weed.

Information:

These risks, while tangible, present challenges to crop management programs rather than a likelihood of ecological disaster. One needs to be aware of the agricultural ecosystem in each specific case.

Risk 3

Drift of pollen from a GM crop into an organic crop could result in loss of organic certification.

Facts:

There are reports that this has occurred (and even resulted in a lawsuit), although the frequency of this happening is unknown.

Information:

We know how far pollen from most crop plants will travel. Again, it is more of a management problem than a biosafety issue. Growing crops where there is no tolerance for any genetically modified material near GM crops needs to be avoided.

Risk 4

There may be unintended harm to wildlife and beneficial insects.

Facts:

There is some risk that this may occur, but the true extent of the risk is unknown. The widely cited Monarch butterfly study from Cornell University is a good case in point, which showed that pollen from Bt corn could harm the butterfly larvae. However, this study did not simulate real world conditions. The Cornell study did, however, stimulate considerable research, much of which is still underway at many universities, including Iowa State University. It remains to be seen whether pollen from Bt corn has an adverse effect on nontarget organisms.

Risk 5

Persistence of Bt from residue of the previous crop in soil may depress microbial activity.

Facts:

While a few studies have pointed out that Bt can be detected in soil residues up to eight months after harvest, effects on soil microbial activity are unknown and unlikely. There is no research to indicate any effects on soil microbes. Bt toxins are highly specific for certain insects and not known to affect other life forms. Undoubtedly, this will be the subject of further research.

Risk 6

There have been claims that genetic engineering of food crops may result in food that is in some way harmful or less nutritious.

Facts:

At this time, there is no direct evidence to support this contention.

Information:

There is one report suggesting that GM soy may have a reduced level of phytoestrogens. This has not been confirmed. Another widely cited report from Scotland claimed that GM potatoes had severe effects on laboratory rats. However, this study was not done using commonly accepted standards for scientific research. These potatoes were engineered with a gene that will not likely ever be used for human or animal consumption. The focus of the research was to identify genes that may prove to be useful for developing plants with resistance to aphids.

People need to realize that testing food for potential health effects is, in fact, technically very difficult. Most GM crops have been analyzed for content in terms of all of the components food scientists and nutritionists measure. To date, no substantial differences have been found between a GM and a non-GM food source.

Risk 7

Certain gene products may be allergens, thus causing harm to human health.

Facts:

Certain gene products do indeed result in production of allergens.

Information:

Work done several years ago to increase the content of certain amino acids in soy used a Brazil nut gene. While the experiment was successful, the protein was also an allergen and, consequently, the product never left the laboratory. Clearly, such a product would likely never enter the marketplace, and would be a commercial dead end. However, better tests for allergenicity of food products are needed. Improved testing methods would assist in the process of removing any product that might cause an allergic reaction.

Risk 8

Certain religious groups or people with certain moral convictions might find consumption of GM crops or their products objectionable.

Facts:

This is a concern and needs to be addressed.

Information:

There has been research in which certain genes from animal sources have been inserted into plants. At this point in time, no company developing GM crops is even contemplating trying to commercialize a product containing a gene from an animal source. Similar to the previous case with an allergen, a product with a mammalian gene, for example, would likely be a commercial disaster to say the least.

Risk 9

The antibiotic selectable marker gene used in many GM crops could increase levels of antibiotic resistance in humans or other animals.

Facts:

In almost all cases where an antibiotic marker gene has been used, it has been a gene (neomycin phosphotransferase II) that detoxifies the antibiotic kanamycin. (This antibiotic is used for plant genetic transformation work, since it is highly phytotoxic and thus is a highly effective marker for detecting rare transformation events. Plant cells receiving the kanamycin gene along with the other genes of interest are able to thrive on culture media containing the antibiotic. Normal unaltered cells are not able to survive.) While this is a legitimate concern, the probability of this actually occurring in nature is infinitesimally small. Furthermore, this gene is ubiquitous in nature.

Information:

The antibiotic kanamycin is used only rarely today, primarily for certain veterinary applications. The probability of an antibiotic resistance gene, or any gene for that matter, to cross from ingested DNA into a host genome is zero or close to zero.

Risk 10

There is concern among many that research and development of GM crops is largely controlled by large multinational corporations, leading to products that may not be in the best interest of the public. Corporations could gain control of entire food production systems.

Facts:

This is a concern and needs to be addressed.

Information:

Market forces greatly impact how GM products are developed and ultimately marketed. Whether individual corporations will, in fact, obtain control of entire food production systems remains to be seen, but considering the wide range of products, the wide range of laws around the world, and variable rates of consumer acceptance, it would seem unlikely that this will happen. Farmers also have a say in how this transpires, and, even today, the vast number of farms are still relatively small: 94 percent of all U.S. farms have gross annual incomes of less than $250,000.

Summary

The first products of agricultural biotechnology are now in the marketplace. These products represent the first generation of GMO technology. We will soon see GM crops with multiple genes and traits; in a few instances this has already happened. In the future we will see crops that have been modified as a result of the recent boom in genomics and proteomics, which will allow scientists to perform the equivalent of gene therapy on a plant. They might make as few as one change in a plant’s genome in order to change a trait, and do it without the need for foreign genetic information. The potential of current technology is great for reducing production costs while increasing the yield, quality, and safety of our food supply. The potential of technology on the horizon is even greater. New technology does not, however, come without risks. Considerable research is needed to understand these risks and to develop methods to manage them.