October 1, 2012 (Vol. 32, No. 17)
Henry I. I. Miller, M.D. Physician and fellow Stanford University
Fear-Mongering About Recombinant DNA-Modified Crops Hurts Farmers and Consumers
Most people are familiar with the unappetizing browning of apples shortly after they’re cut or bitten into. The good news is that molecular biologists have devised a clever way to prevent it. The bad news is that organizations that represent apple growers are implacably opposed to the improved fruit.
And therein lies a cautionary tale.
The biology of apples is complicated but fascinating. Almost all commercial apple varieties are grafted onto hardy root stocks that have dwarfing genes to keep the trees on apple plantations short and easier to harvest. Therefore, the DNA of the roots is different from the DNA of the fruit tree.
Apples’ blossoms are self-incompatible with respect to fertilization so they must be cross-pollinated by insects (primarily bees) in order to develop fruit. Special pollinating trees are found in most orchards as a source of pollen for the fruit tree blossoms. These pollinating trees (often crab apples) have still different DNA. Once the pollen fertilizes the apple blossom the fruit can develop.
The pollen DNA mixes with the flower ovum DNA and the resulting hybrid seed embryo grows and produces a hormone that directs other parts of the flower (which contains only flower DNA) to develop into the fruit. Thus, the DNA in the fruit itself is different from the DNA in the seeds.
This difference in DNA between the fruit and the seeds is why different varieties of apples can be grown in close proximity and yet maintain their differences. Because the DNA in the fruit is only from the flower, not the pollen, Granny Smith apples growing next to Golden Delicious growing next to Red Delicious all produce apples with their own unique DNA.
A Canadian company has petitioned both the U.S. and Canadian federal regulatory authorities to permit the sale of a new variety called Arctic® Apple that contains a commercially significant trait. It is highly resistant to the unappetizing browning that occurs when an apple is cut or bruised. The biology that made this possible is elegant and intriguing.
Enzymatic browning is caused by the apple’s chemical reaction to cell injury, such as when the fruit is bitten or sliced, which ruptures the cells and triggers a chemical reaction between an enzyme called polyphenol oxidase (PPO) and chemicals in the apple that cause the apple flesh to turn brown. A family of four genes controls the majority of PPO production, so scientists turned off those genes—and lo and behold, Arctic Apples don’t manifest enzymatic browning.
Ordinarily, this development of another new apple variety would be a nonevent—except, perhaps, for apple growers and retailers who would, one would expect, relish a new product with additional appeal to consumers—but the seeds of discontent have sprouted: Because the shutoff of the four genes was done with recombinant DNA technology, there have been objections and consternation.
Simply because this highly precise and predictable methodology was used, some apple growers are worried that this new variety could constitute a threat to other apple crops. The U.S. Apple Association (USApple), the industry’s trade group, says that it “supports advancements from technology and genetics and genomics research,” and that “benefits can include attributes such as quality…”—which would certainly include nonbrowning apples—but, paradoxically, USApple has also come out firmly against the introduction of the Arctic Apple.
USApple has emphasized that its objections are “not based on any concern about human health and safety,” but “consumers like their apples and are not calling for these new ‘nonbrowning’ cultivars.” How lame. Are consumers clamoring for apple cultivars that are more resistant to predation by insects, viruses, or fungi?
There are several reasons why their concerns are unfounded.
First, as described, farmers and plant breeders have been creating new varieties of apples for millennia. The new molecular techniques for accomplishing this are far more precise, predictable, and conservative.
Second, there is vast experience in both cultivation and in our diets with recombinant DNA-modified varieties of various crops. Farmers in three dozen countries have cumulatively cultivated more than 1.25 billion hectares (about 3.75 billion acres) of them, and North Americans alone have consumed more than 3 trillion servings of food or ingredients from recombinant DNA-modified plants. There has never been a single documented case of disruption of an ecosystem or harm to a person.
Extensive global scientific research has identified no unique health risks associated with recombinant DNA-modified crops or food, and the apple growers associations (except perhaps the organic growers, who often seem to reside in a parallel universe) have no concerns about the safety of this nonbrowning apple.
Could the new apple “contaminate” other varieties? Research has shown that the cross-pollination potential of apples is limited to about 150 feet. Beyond that distance, cross pollination of apples is virtually nil. The DNA in fruit comes from the parental tree, not the pollen that fertilizes the apple blossom. When someone eats a Golden Delicious apple, 100% of the DNA (and protein, carbohydrates, and other compounds) is from Golden Delicious trees.
The entire apple industry owes the diversity of varieties to different gene expression patterns. A Golden Delicious apple looks and tastes different from a Red Delicious because different apple genes are expressed. Recent genomic sequencing shows there are about 57,000 genes in the Golden Delicious apple. One must look beyond the science to understand how the apple growers’ associations can be against new varieties of apples simply because four of the 57,000 apple genes have been turned off.
The reason is short-sighted economics. A spokesperson for the Northwest Horticultural Council ascribed the apple industry’s opposition to the potential for “severe adverse marketing issues to confront both organic and traditional apple growers” if the Arctic Apple were to be introduced.
The organic fruit industry is especially antagonistic to the Arctic Apple. They claim that the organic status of their fruit is threatened by cross-pollination from any recombinant DNA-modified apple and are calling for a ban on all such varieties. However, no organic grower has ever lost organic certification from exposure to trace amounts of recombinant DNA-modified seed or pollen, just as pesticide wafting onto organic crops from neighboring fields does not jeopardize organic status.
“Organic” status is conferred if the grower agrees to use only a restricted set of techniques and practices but has nothing at all to do with the quality, safety, or characteristics of the product itself.
Fear-mongering about recombinant DNA-modified crops has become the stock-in-trade of some antitechnology environmental organizations and the organic food industry. Therefore, apple growers and their trade groups fear the possibility that their products will no longer be the “apple of the consumer’s eye” because of negative propaganda from the organic food and antibiotechnology organizations.
There are even more compelling reasons than pleasing their customers for apple growers and their trade groups to embrace the new technology: the experiences, both positive and negative, of other farming sectors in the recent past.
Recombinant DNA Technology
Consider, for example, the cautionary tale of the Kona coffee industry in Hawaii, which in 2008 pushed the Hawaii County Council to ban the growing of recombinant DNA-modified beans on the Big Island. The growers felt that the use of the new technology would risk decades of building the reputation of Kona coffee as a brand. Beans developed using recombinant DNA technology may not qualify as “specialty coffee,” and therefore, it was feared that they would command a lower market price.
The industry may now be singing a different tune. Big Island coffee growers are facing a dire threat to their crops that didn’t exist four years ago: Infestations of the Coffee Berry Borer beetle, which evolves resistance to pesticidal sprays, were first discovered in Kona in 2010 and have now been confirmed in all parts of west Hawaii and in some other areas as well. Faced with the threat of devastation of their crops, the industry is now desperate for any measures to combat the beetle. Recombinant DNA technology has been widely and successfully used in corn, cotton, papaya, and other crops to introduce resistance to pests.
Hawaiian coffee farmers and their organizations should have heeded the positive example of the Rainbow variety of papaya, Hawaii’s fifth largest crop. By inserting a single gene from a virus into papayas, scientists have made them virus-resistant. Although the biological mechanism is different, the effect is similar to vaccination of people and animals using weakened or killed viruses. The recombinant DNA-modified Rainbow papaya has resurrected Hawaii’s $64 million-a-year industry, which was moribund 15 years ago because of the predations of papaya ringspot virus.
Wheat farming offers yet another example. By 2004, Monsanto, the world’s leader in the production of seeds for genetically engineered crops, had made substantial progress in the development of genetically engineered wheat varieties for North America. But suddenly in that year, the company scrapped its wheat program in large part because of opposition from North American grain merchants and growers.
European countries and Japan, which have traditionally imported about 45% of U.S. wheat exports, have been resistant to recombinant DNA-modified crops and food derived from them.
However, American growers and millers have had a change of heart. Wheat farming is a struggling industry in the United States, in large part because it has not received the technological boost from recombinant DNA technology that has hugely benefited the corn and soybean sectors. U.S. wheat acreage is down about one-third from its peak in the early 1980s, due to reduced profitability compared with alternative crops. Therefore, in 2006, a coalition of U.S. wheat industry organizations called for access to recombinant DNA-modified wheat varieties with enhanced traits, and a survey released in 2009 by the U.S. national association of wheat growers found that more than three-quarters of U.S. farmers wanted access to genetically improved varieties with resistance to pests, disease, drought, and frost.
Such varieties are important as plant scientists and farmers continue to battle diseases such as leaf rust, the world’s most common wheat disease, which can lead to yield loss of up to 20%. In Kansas, the heart of the U.S. wheat belt, for example, leaf rust destroyed a shocking 14% of the wheat crop in 2007.
Apple growers should take note of the lessons learned by others the hard way. There is little doubt consumers will like and even pay a premium for the nonbrowning trait in apples. Instead of fighting the introduction of this improved, consumer-friendly product (as well as others that could follow), the apple growers’ associations should sow the seeds of greater sales and security of their harvest by mounting a truthful, positive ad campaign to trumpet the new advances in molecular biology applied to their products. They should bear in mind that technophobia often breeds poisoned fruit.
Henry I. Miller, M.D. ([email protected]), is the Robert Wesson fellow in scientific philosophy and public policy at Stanford University’s Hoover Institution. Robert Wager, a biologist, is on the faculty of Vancouver Island University.