Genetically engineered fruits and vegetables

Genetically engineered fruits and vegetables
By Dorothy Noble

Without pesticides or Bt corn, this fall armyworm will devour any sweet corn as quickly as this blue flour corn.
Photo by Bob Ferguson.

One thing is certain about genetically engineered foods: They stir emotional discourse. On one side, opponents fear insufficient testing and distrust the science and the companies. On the other side, supporters feel genetic engineering is a long-term solution to the problem of feeding the world. Surveys have shown that a majority of people think labels should indicate if food is genetically modified.

Environmentalists point to reduced pesticide use with biotechnology. Organic enthusiasts fear that organic certification will be threatened.

Vegetable and fruit crops have been genetically modified for 20 years to fight persistent pests, enhance desirable traits, or deter certain natural characteristics of the product. And many more genetically modified varieties are currently being developed. A spinach gene inserted into a citrus plant could prevent the greening disease (huanglongbing) now plaguing the citrus industry.

The National Academy of Sciences, the American Association for the Advancement of Science, the American Medical Association and others have concluded that genetic engineering poses no hazard to human health or the environment.

Put simply, genetic engineering allows genes to be transferred from one organism to another, altering the genetic material (DNA). Although genetically engineered, or GE, is the generally preferred term, GMO (genetically modified organism) remains popular.

Calgene's Flavr Savr tomato was marketed in 1994, but ceased production in 1997. This genetically engineered tomato had a gene that interfered with the enzyme that softens vine-ripe tomatoes, thus allowing shipped tomatoes to ripen on the vine for full flavor. Costs rendered the venture unprofitable and prompted the sale of Calgene to Monsanto.

In 1995, Monsanto received regulatory authorization for its NewLeaf potato, a Russet Burbank using biotechnology to resist the Colorado potato beetle. This potato was modified with Bacillus thuringiensis (Bt), as were NewLeaf Atlantic and NewLeaf Superior potatoes later on. By the late 1990s, Monsanto had developed potatoes with resistance to potato leafroll virus and potato Y virus, in addition to insect protection. Monsanto reports that in 2011 it decided to focus on the following row crops: field corn, soybeans, wheat and cotton.

The majority of row crops grown in the U.S. today are genetically engineered. In comparison, far less GE produce has been marketed. Except for GE Hawaiian papaya, which has been in production for a number of years, the characteristics of several important produce items being grown now or in an advanced stage of development or approval are described below.
Sweet corn

Syngenta's Attribute insect-protected sweet corn has been grown in the U.S. for 15 years. A full range of white, yellow and bicolored varieties (including sugar-enhanced and supersweet transgenic hybrids) has been produced to control European corn borer, corn earworm and fall armyworm. Field trials have consistently shown a substantial reduction in insecticide use. The company's Attribute II technology provides increased control.

Monsanto's Seminis has marketed the pyramided Bt sweet corn under the Performance Series brand name. These transgenic hybrids incorporate the Roman numeral II in the names. Control includes numerous above and belowground worms, borers and rootworms. This series also has the herbicide tolerance trait.

Since these new hybrids provide different modes of action, resistance is thwarted.

Barry Rupp of Rupp Seeds observes that in many areas, "Using Bt varieties is the only possible way to grow sweet corn at the end of August and September without spraying every two to five days."
Summer squash

Virus-resistant transgenic summer squash has been available to commercial growers since the mid-1990s. In 1997, the state of Georgia reported an economic loss of $2.6 million from squash viruses. Resistance to zucchini yellow mosaic virus (ZYMV) and watermelon mosaic virus (WMV) was shown to be durable in studies for USDA's Agricultural Research Service by Ferdinand Klas and others in 2010. The data showed that under high disease pressure, fruit yield and marketability of the transgenic squash was much higher than that of nontransgenic summer squash. The researchers concluded that virus-resistant transgenic crops provide a sustainable approach for controlling plant viruses.

Aphids spread ZYMV and WMV. Pesticides can control aphids, but once they're present, it's likely the insects have already damaged the plant. Some of the recently developed Seminis varieties also resist cucumber mosaic virus and powdery mildew. These cultivars typically include a Roman numeral designation along with the conventional name.

The tomato plant on the left, VF 36, has succumbed to bacterial spot, but breeder Jay Scott's Florida 8314 Bs2 on the right shows resistance and is bearing tomatoes.
Photo courtesy of Jay Scott.
Tomatoes

University of Florida tomato breeder Jay Scott has developed a plethora of successful commercial tomatoes. However, for decades he has tried to breed resistance to bacterial spot into tomatoes. With support from the Two Blades Foundation, Scott has been developing a transgenic tomato using a gene from a close tomato relative, a pepper with bacterial spot resistance. The pepper gene Bs2, transferred into a California tomato and into Scott's Florida 8000 inbred tomato, has provided clean resistance to bacterial spot races T3 and T4. Fall 2011 and spring 2012 trials showed impressive yields.

Using Florida 8000 as a parent in hybrids and Florida 8314 for its reliable fruit setting ability, bacterial spot resistance could eliminate copper sprays entirely. Also, adding yellow leaf curl virus resistance to Florida 8314 could give growers more reliable yields. Scott observes that genetic engineering offers considerable environmental advantages if buyers will accept it. He states, "As scientists, we have a duty to put out the research."
Potatoes

With over 60 years of experience in the potato business, the J.R. Simplot Co.'s plant sciences team in Boise, Idaho, researches methods to improve multiple facets of this important food. Simplot has initiated the FDA voluntary safety review process with its Innate potato. Using the potato's own DNA, the Innate technology allows scientists to isolate genetic elements from a potato plant genome, rearrange them, link them in more desirable permutations, and then incorporate them back into the genome. Thus, nothing more than the potato's own genes is used.

Traditional crossing of potato plants, of course, involves genes from more than one potato plant. The process itself, plus extensive trials, renders new variety development or variety improvement a lengthy process, typically well over a decade. Genetic engineering yields results in a fraction of the time.

The first generation of Innate potatoes improves Russet Burbank, Ranger, Atlantic and Snowden by incorporating benefits to both growers and consumers. These potatoes feature reduced black spot from bruising, no susceptibility to browning when cut, reduced potential for acrylamide in high-temperature cooking, and reduced sugars that provide consistent golden coloration.

Extensive field trials in 12 states, including states in the Pacific Northwest, Midwest and Southeast, revealed no differences in flavor or growth characteristics from conventional potatoes.

Simplot is seeking import approval in Canada, Mexico and Japan.

Haven Baker, vice president of Simplot Plant Sciences, says, "Innate has the potential to improve potatoes for consumers, processors and growers and help meet the worldwide demand for better, more consistent crops in the years ahead."
Apples

When cut, apples release an enzyme that mixes with phenolic compounds and oxygen to cause browning. Okanagan Specialty Fruits (OSF) in British Columbia has developed the Arctic apple to counteract that process. OSF uses genetic engineering to halt the production of the enzyme that triggers browning by inserting a synthetic gene sequence that is derived from apples. The transformed Arctic apple plantlets are grafted onto rootstock and grown in a tree nursery before being transplanted into an orchard, just as other apples are produced.

The gene sequence employed is recognized as harmless to humans. OSF says the apples can potentially cut waste, are ideally suited for fresh slices, and exhibit the browning resistance, contributing to better taste and texture. The company can engineer any variety to be nonbrowning. OSF has petitioned the USDA to deregulate Arctic Golden and Arctic Granny. In this review, pending approval by the USDA, the company must demonstrate that the trees do not pose a plant risk. In addition, although not required, OSF has voluntarily consulted with the Food and Drug Administration (FDA) to show that Arctic apples are as allergen and toxin-free as other apples. Health Canada is also reviewing the apples for safety, and the company has also petitioned the Canadian Food Inspection Agency for deregulation.

Neal Carter, OSF president and founder, says, "We expect to complete the rigorous regulatory requirements in the U.S. and Canada and receive commercial approval later this year, with small quantities of fruit available beginning in late 2014." He adds, "We have approximately 10 years of real-world field trial experience demonstrating that our Arctic trees behave no differently than conventional trees, and Arctic apples are compositionally and nutritionally similar to conventional apples."

Okanagan Specialty Fruits has petitioned the USDA to deregulate its nonbrowning Arctic versions of Granny Smith and Golden Delicious apples.
By Jorcoga, via Wikimedia Commons

Regulation

Early in the development of genetic engineering agriculture, the federal government in 1986 decided that GE crops should be regulated using existing statutes. The FDA is responsible for food safety and maintains a voluntary consultation process with developers. Advocates for labeling have objected to the FDA's response that genetically engineered food need not be labeled as such if the product is not materially different relevant to food safety. For deregulation, the USDA determines whether GE crops harm other crops or the environment. The Environmental Protection Agency (EPA) reviews and approves the GE product and its effects if the added pesticide is safe. Herbicide-resistant and Bt GE products also fall under EPA oversight. For these, the EPA imposes restrictions on usage to reduce the chance of resistance.
Choices

Numerous seed companies do not offer genetically engineered varieties. About 15 years ago, the European company Bejo Seeds decided to pursue development of organic vegetables instead, according to Jan van Der Heide, sales and product development manager. New developments in traditional breeding, such as genetic marker technology, can select desirable genes in the laboratory without modifying DNA. He says, "We can now make crosses for horticultural traits and, for instance, assess and select seedlings for fruit quality, disease resistance, size, color, growth habit and more."

Seedway distributes organic, treated, untreated and transgenic commercial vegetable seeds. Dean Cotton, vegetable seed manager at the Elizabethtown, Pa., office, reports that there are customers who recognize the benefits of genetic engineering and others who don't feel it offers the benefits of organic production. Cotton says, "We try to provide a good representation of products and let the customer decide."
Advocacy

The Just Label It organization began its initiative in September 2011. The group, with 1.2 million comments, petitioned the FDA in March 2012 to require labeling of genetically engineered foods. No official action has taken place yet. Katey Parker, partnerships and media manager of Just Label It, reports, "We continue to push members of Congress, the White House and FDA to institute mandatory labeling of genetically engineered foods." The organization monitors news and events, both nationally and by state, regarding GE developments on its website, www.justlabelit.org.

The National Sustainable Agriculture Coalition (NSAC) represents numerous grassroots organizations, including organic groups working to advance the sustainability of agriculture, food systems, natural resources and rural communities. The NSAC supports mandatory federal labeling, citing consumers' right to know what is in their food, and a mandatory review process to assess the safety of genetic engineering. Among other positions, the NSAC supports policies that eliminate or minimize contamination of non-GE crops, while urging public funding of classical breeding programs for non-GE public crop varieties that are regionally adapted and suited to sustainable and organic production systems.

In late July, a group of biotechnology companies launched a "GMO Answers" website to respond to tough questions regarding the health and safety of genetic engineering. Karen Batra, director of communications for the Council for Biotechnology Information, a sister group of the Biotechnology Industry Organization, reports that in the first 10 days, many conversations began with preconceived notions, but they provided good feedback. The website (www.gmoanswers.org) provides information regarding many typical questions, such as GMO basics, regulations, labeling and future developments. The site identifies the experts responding to the conversations and posts the answers. Specifics such as the impact on genetic diversity and potential herbicide resistance are explained, and others frequently join the conversation.

The Center for Science in the Public Interest (CSPI) last fall urged tougher GE oversight in the farm bill. In February, it called the EPA's attention to the emergence of herbicide-resistant weeds in GE crops, and in March the CSPI asked the USDA to take steps to limit GE crops' unintended impact on neighboring crops.

Michael Jacobson, CSPI's executive director, states, "In general, GE research is a powerful tool to develop new crops that could provide tremendous benefits. Bt cotton reduces the need for dangerous pesticides, and the citrus greening in orange groves in Florida, Texas and California is solvable using genetic engineering."

Jacobson stresses, "So far there have not been any health risks whatsoever of crops in production." However, he says it's clear that this biotechnology can affect agriculture in a negative way. Noting that the prevalent use of Roundup Ready and Bt varieties year after year in the same fields could lead to highly resistant weeds and insect resistance, he says, "It is important to farmers and the biotech industry not to overdo." He urged the use of other methods such as crop rotation and rotating pesticide modes of action, for example. He also pointed out that mixing GE with non-GE crops presents a risk for exporting.

Finally, Jacobson says, "The industry has been careless, almost on the verge of killing this tremendously powerful technology. If nobody wants to eat the products, higher levels of pesticides will be used." He adds, "Critics have been very vocal in their demands. Proponents have done a very poor job of using the technology safely."

The author is a writer-researcher specializing in agriculture. She currently resides in central Pennsylvania.