By Mary C. Gruszka
Genetic engineering and genetically modified organisms can be controversial subjects. Growers often have to field questions about GMOs from concerned consumers, and it can be challenging to clearly explain what they are and how they differ from traditional cross-breeding.
So it was timely that the keynote speaker at the recent Empire State Producers Expo in Syracuse, Dr. Margaret Smith, Pant Breeding and Genetics, Cornell University, presented a clear and concise overview of genetic engineering (GE), a comparison with traditional plan breeding, commonly grown GE crops, a review of scientific studies on the impact of GE crops and safety, and what to expect in the future.
In her presentation, “GMOs: Distinguishing Fact from Fiction,” Smith said that genetic engineering is a logical extension of what plant breeders have always done, starting with domestication, and continuing to intentional selection of new crops and varieties and traditional cross-breeding. “Genetic engineering is a new tool to breed improved crops,” she said.
Smith noted that she is a traditional plant breeder who doesn’t work in genetic engineering. She cited studies that show “most people have never heard of plant breeding,” and that study respondents did not realize that they most likely had eaten fruits or vegetables that were products of traditional cross-breeding.
In traditional cross-breeding, genes from two parents are combined in an offspring which contains a mix from each. There can be mistakes, called mutations, in copying genetic code. This often produces undesirable characteristics in a plant, but sometimes something useful results. And these plants can then be selected for future breeding.
On the other hand, genetic engineering, as Smith defined it, is the transferring of individual genes between organisms or modifying a gene within an organism. “With genetic engineering you change genes in the DNA so there is no need for sexual cross-compatibility,” Smith said. “There’s no mixing of genes like in traditional cross-breeding,”
For consumers, Smith said, the benefits of genetic engineering aren’t clear and there’s the concern that comes with new technologies.
Since introduction in the 1990s, GE crop production has increased exponentially, with corn, soybeans and sugar beets, leading the way. For GE fruits and vegetables it’s harder to tell which of the approved varieties of plum, apple, radicchio, squash, potato, peanut, tomato, papaya, eucalyptus, flax, and rose are in actual production.
GE crops grown in the US fall into three general categories – Bt, herbicide resistant, and virus resistant.
The Bt crops include corn, cotton, and sweet corn. These are toxic to certain insects especially Lepidoptera, when they ingest this type of plant.
The herbicide resistant crops include soybeans, corn, cotton, canola, sugar beets, and alfalfa. The virus resistant crops include papaya in Hawaii and some summer squash.
Some GE crops like field corn are stacked, meaning that they contain both Bt and herbicide tolerant genes. “Over 90 percent of the field corn in the US is stacked,” Smith said.
In 2014, new GE crop varieties that were approved include an insect resistant soybean, a reduced lignin alfalfa, a potato with reduced black spot bruises and low acrylamide production, soybean varieties with 2, 4-D, dicamba, HPPD tolerance, and a dicamba tolerant cotton.
“We’ll see what happens with potatoes. They are currently building up seed supplies,” Smith said. However, “one fast food chain said that they won’t use it,” she added.
GE crops that are being considered, but not yet approved include a non-browning apple, a potato with late blight resistance, reduced black spot bruise, low acrylamide potential, and lowered reducing sugars, and a 2, 4-D resistant cotton.
As for the farm-level impact of GE crops, Smith reported that a 2010 National Research Council (NRC) study from the National Academy of Sciences (NAS) found that more herbicides were used, but a less toxic one. This allowed more reduced tillage practices. Glyphosate use is on the rise, as are the instances of weeds that have evolved resistance. Fewer insecticides are being used. However, corn rootworm has evolved to be resistant to insecticides and crop rotations.
Why the weed and insect resistance? “We forgot that pest management is not a silver bullet,” Smith said. “You can’t use the same management year after year. The pest will get a resistance.” Another reason is that stacked varieties are providing insect control whether it’s needed or not, and exposes the insect population to select for resistance. “Let’s not forget our IPM muscles,” Smith said.
The NAS-NRC study found that for farmers, they benefitted economically in growing GE crops with advantages for worker safety and convenience. However the study concluded that the social impacts, as well as effects on prices and growers who don’t use GE crops aren’t well understood and that there needs to be more study of market concentration of GE seed producers.
Market concentration has been increasing with about three-quarters of approved GE crops controlled by four companies, Monsanto (with the largest proportion), Dupont, Syngenta, and Aventis
Whether there’s too much concentration, is not a science question, Smith said. Rather, it’s a social issue that relies on the political process.
Smith said that 60 to 70 percent of supermarket foods have ingredients from a GE variety, especially products made with soy or corn or with their derivatives. And this raises the question, is it safe to eat these foods.
Smith explained that food safety tests are focused on compounds that are novel or unique. A 2014 summary of over 1,700 studies about food and feed safety and the environmental impact of GE crop products found no credible evidence of safety concerns. “There were studies that expressed safety concerns but they were discredited as to validity,” Smith said.
This led into the topic of labeling and how to determine if a food or refined ingredients are genetically engineered or derived from GE foods. Smith explained that if a food, like whole produce, contains protein, there are measurements to detect the DNA and to see if it’s been modified.
But if an ingredient that is derived from a plant, like vitamins, lecithin, canola oil, or corn starch, does not contain protein, there’s no DNA present to analyze. Corn starch, as an example, is made up of chains of glucose molecules, Smith said. “No DNA, no protein.” Beet sugar was another example Smith gave. It’s composed of sucrose and is identical to cane sugar. “Both are purified to be just sugar,” Smith said.
This can complicate labeling. Smith showed a slide listing over 50 common food ingredients that are derived from corn or soybeans. A cereal, for example, could make a claim that it contains no genetically modified ingredients if the ingredients themselves don’t have any GE components, even though those ingredients could have been derived from GE plants.
Labeling will have a cost for the consumer. Smith said estimates vary, but for New York it could be around $500 a year increase in food costs for a family of four. Smith explained that while the cost of the label itself is small, most of the expense involves tracking every chain in production. Smith said that consumers already have choices in certified organic, non-GMO verified and other voluntarily labeled food products.
So are we eating foods with ingredients from GE crops? Most likely we are, but as Smith said, “most are refined ingredients with none of the novel DNA or protein in them.” The exception would be GE fresh produce as sweet corn, papaya, and some summer squash. “Credible evidence to date shows no risk,” Smith said. “But future products need to be evaluated.”