GMO crops differ from traditional breeding techniques

Developing crops that are disease resistant or produce a desired trait such as sweetness, flavor or color has long been a goal of people who breed plants. But the introduction of laboratory techniques to modify plants in ways that would usually not occur in nature is one of the concerns that has fueled the GMO debate.

For instance, if you take conventional or traditional plant breeding, you crossbreed two varieties of a plant to combine two traits.

"Depending on the species, natural cross-breeding is easy. For some plants, you have to physically make the cross," said Jim Myers, professor of vegetable breeding and genetics in the department of horticulture at Oregon State University.

So you get the cross seed, and you plant that seed and grow it out to the next generation. And usually, you have to go through some sort of sorting process, Myers said. That first generation will have a combination of traits of both of the parents, and they will not breed true. If you cross-pollinate them, you get a number of traits. So what a breeder has to do is go through five or six generations of self pollination to get a plant that will breed true for a desired trait.

For gardeners who are familiar with tomato or other hybrid seeds, this is a familiar process. If a gardener tries to take seeds from a hybrid plant and save the seed to grow, the result will not produce true to the parent plant, and the result could be quite variable, Myers said.

Conventional plant breeding and propagating methods also make use of grafting, the process where two different varieties are physically combined by grafting stems or tops of one variety with the root stalk or the main trunk of another variety. This method is common in wine-grape growing, where European wine grape varieties are grafted onto the root stalk of native American root stock in order to make the vine immune to phylloxera, a vineyard root pest that attacks the roots of European grape roots. American grape roots are immune to the pest.

Grafting also is the method that's commonly used to produce multiple varieties of fruits on the same tree, Myers said. This works with fruit trees within the same species such as plums, nectarines and peaches being grafted together, or different varieties of citrus, apples or pears grafted together.

In genetic engineering, the process moves from the greenhouse to a laboratory.

"What you're talking about is selecting a recipient parent and then a gene from somewhere else, from another plant, an animal or bacteria," Myers said.

The gene is isolated and then introduced into a plant tissue culture in the lab through the use of an agrobacterium, a natural plant pathogen that is used to genetically engineer a plant by attacking the plant's cells and inserting the desired gene into the host cell. It also can be done with particle bombardment, where a microscopic piece of gold is coated with DNA and then bombarded into the plant cell, Myers said. "This whole process is done in a lab," he said. The plant tissue is then cultivated.

The most common GMO crops in America are corn, soybeans, canola, cotton and sugar beets, Myers said. And these plants have been genetically engineered for basically two traits: herbicide and insect resistance, Myers said.

The majority of herbicide-resistant crops are called Roundup-ready crops, said Carol Mallory-Smith, professor of weed science at Oregon State University. Crops such as soybeans, corn, alfalfa, cotton and sorghum have been engineered to be herbicide resistant. A gene in a bacteria strain was discovered that would make plants insensitive to glyphosate, the major ingredient in Roundup that kills weeds, Mallory-Smith said. So these plants have been engineered with this gene so that the crop fields could be sprayed with Roundup to kill weeds without killing the crop plant.

"This lets farmers control weeds and increase yields," she said.

The other major use for genetic engineering in plants is to control damaging insects. A gene from a bacterium called bacillus thuringiensis (BT) is introduced to plants so that the plant itself produces toxins that kill insects when the insects try to eat the plant. This allows farmers to grow crops that are resistant to insects without having to spray pesticides, Mallory-Smith said.

Scientists discovered that specific strains of BT produce toxins that are fatal to specific species of insects, Myers said.

"The particular form of BT used is specific to the insect you're targeting," he said.

For instance, the BT used in genetically engineered corn is specific to either butterflies or beetles.

Other genetically engineered crops such as Hawaiian papaya and some zucchini and yellow squash crops have been genetically modified to be resistant to viruses.

"For papayas it's the ringspot virus, and in squash, it's zucchini yellow mosaic virus," Myers said.

What some researchers found many years ago is if you took the gene for the virus that produces a certain protein coating and insert that virus into the plant, then it became resistant to that virus, Myers said. In a way, it's a similar process that's used to develop vaccines in humans where vaccines made from dead or inactive versions of disease-causing organisms are injected into your body to help the body produce an immunity to those organisms.

According to the U.S. Department of Agriculture, the top three GMO crops grown in this country are corn, soy and cotton. In the last 12 years, the percentage of acreage planted with GMO has risen to more than 80 percent for each of these crops.

For consumers concerned with avoiding GMO food crops, these staggering statistics make avoidance of such products increasingly difficult.

Genetically engineered (GE) varieties with pest-management traits became commercially available for major crops in 1996, according to "Genetically Engineered Crops in the United States," a report prepared by researchers at the USDA.

"More than 15 years later, adoption of these varieties by U.S. farmers is widespread, and U.S. consumers eat many products derived from GE crops — including cornmeal, oils and sugars — largely unaware that these products were derived from GE crops.

"Despite the rapid increase in the adoption of corn, soybean and cotton GE varieties by U.S. farmers, questions persist regarding their economic and environmental impacts, the evolution of weed resistance and consumer acceptance," the report's authors, Jorge Fernandez-Cornejo, Seth Wechsler, Mike Livingston and Lorraine Mitchell said.

"As of September 2013, about 7,800 releases were approved for GE corn, more than 2,200 for GE soybeans, more than 1,100 for GE cotton and about 900 for GE potatoes. Releases were approved for GE varieties with herbicide tolerance (6,772 releases), insect resistance (4,809), product quality such as flavor or nutrition (4,896), agronomic properties such as drought resistance (5,190) and virus/fungal resistance (2,616)."

"The institutions with the most authorized field releases include Monsanto with 6,782, Pioneer/DuPont with 1,405, Syngenta with 565 and USDA's Agricultural Research Service with 370."

In addition to those GMO crops already approved, there are new plant and animal varieties waiting in the wings or that have recently been approved.

Potatoes and apples: The Food and Drug Administration recently approved apples and potatoes that are resistant to bruises and don't go brown as safe to eat. Consumer and environmental groups are concerned that such products could have unknown risks to human health.

The approval covers six kinds of potatoes by Boise, Idaho,-based J. R. Simplot Co. and two types of apples by the Canadian company Okanagan Specialty Fruits.

The USDA's Animal and Plant Health Inspection Service approved them as being safe in mid-February. This authority is, however, primarily is concerned with crops not posing a threat to other plants, while the FDA considers food safety.

Salmon: A company called AquaBounty is currently petitioning the FDA to approve its genetically engineered variety of salmon.

Pink pineapple: Fresh Del Monte Produce Inc. has engineered a pink pineapple that includes lycopene, an antioxidant compound that gives tomatoes their red color and may have a role in preventing cancer. USDA has approved importation of the pineapple, which would be grown only outside of the United States; it is pending FDA approval.

Purple tomatoes: Some gardeners already grow conventional purple tomatoes, but a small British company is planning to apply for U.S. permission to produce and sell a new genetically modified variety that has high levels of anthocyanins, compounds found in blueberries that some studies show lower the risk of cardiovascular disease and cancer. The FDA would have to approve any health claims used to sell the products.

The Associated Press contributed to this story.

Victor Panichkul is food, wine and beer columnist for the Statesman Journal. Reach him at (503) 399-6704 or Vpanichkul@StatesmanJournal.com, follow at Facebook.com/WillametteValleyFoodWine and on Twitter @TasteofOregon.