The Changing Landscape for Crops and Foods
Peggy G. Lemaux, Cooperative Extension Specialist
What Is GM Food Anyway?
I am sure that many of you have read varying stories about the new, what many call GM or GE foods. SLIDE 1 What is a GE food anyway? To answer this question and also to evaluate the risk and benefit questions scientifically, it is important to have an understanding of how genetic methods used to create these foods work. And how are these methods different from or the same as the genetic methods used for thousands of years to change foods.
Let's take a look at grapes. SLIDE 2 Any wine connoisseur knows you can't use muscat grapes to make cabernet sauvignon wine. In fact, about 230 different unique varieties are used for fine wines. It is the uniqueness of the different varieties, their identifiable color and taste, that leads to notable differences in wines. That uniqueness is due in part to the genetic information in the grape, which determines whether it is red or white, sweet or tart. That information is in recipes, or genes, made of chemical units. SLIDE 3 If alphabetic letters are used to represent each unit, 52 books of recipes, each with 1000 pages, are needed to hold all information for a particular grape variety.
What if we wanted a new grape variety? If we used classical breeding, we would cross pollen (male cells) of one variety with eggs (female cells) of another variety and find a grape with new desirable traits. What happens when you do that? Are the two sets of recipe books combined to give 104 books? SLIDE 4 No, genetic rules say only end up with 52 books, so 50% of the recipes from each parent is lost. The breeder can't control which recipes are kept, but only observes the results and chooses the best. This method was used to create varieties like Chardonnay, Zinfandel and Syrah.
But grape varieties have very different characteristics and predicting precisely the traits grapes will have after crosses is difficult. In fact most contemporary grapes varieties are not from recent breeding efforts but are of ancient Middle Eastern or European origin and have been multiplied by cuttings, not seeds. SLIDE 5 Breeding efforts have been used recently with varieties, like Muscadinia rotundifolia, which has resistance to Pierce's Disease, a problem causing millions of dollars in damages to the California wine and grape industry. The attempt is to move that resistance to important wine grape varieties.
New methods exist to facilitate exchange of genes between grape varieties. For example, the Pierce's Disease resistance genes in Muscadinia could be moved into Pinot Noir grapes using two approaches. Both involve using the modern genetic tools, termed genetic engineering (GE), biotechnology, recombinant DNA or genetic modification (GM).
SLIDE 6 One way these new tools can be used is to provide a genetic table of contents for the recipes or genes. Such a table of contents is being developed for the varieties with the Pierce's Disease resistance trait, so it is easier for breeders to select for resistance. Another way to use the new genetic tools is to move specific genes to change a plant's characteristics. SLIDE 7 A single gene, a half page recipe in the 52-thousand-page set of recipe books, can direct the plant to make new traits or remove them. For example, moving the specific gene(s) for resistance to Pierce's Disease from Muscadinia to other grape varieties.
Is classical breeding and genetic engineering the same or different? SLIDE 8 It depends on what aspect you look at. Both use the same cellular machinery to move genes around and both cause heritable genetic changes. So in that sense they are the same. But in the case of classical breeding the change occurs inside the cell, while with genetic engineering it occurs in the laboratory. Also during breeding keeping a particular gene is a random process, while with genetic engineering specific genes are chosen.
Perhaps the most fundamental difference is that gene exchange by breeding takes place most often between closely related plant species, although gene exchange can occur at low frequencies across species barriers. With genetic engineering the gene source can be the same plant, another plant or even different organisms, like bacteria or animals. Why? Because genetic information in all living things is written in the same (chemical) language. In fact humans and plants share many (~40-60%) of the same genes.
So how many of the foods we eat are genetically modified? SLIDE 9 It depends on your definition. If you mean in how many foods have genetic changes occurred, the answer would be all, including those grown under organic certification. Take for example corn whose ancient relative looked little like modern corn. Its seeds were small, in drastically reduced numbers and impossible to open with your teeth. SLIDE 10
If you mean how many different plants have been changed by genetic engineering, the number would be very small. While many processed foods, except those labeled 100% organic, may contain a GE ingredient, they come from a small number of large-acreage GE crops, like corn, soy, cotton or canola. SLIDE 11 In 2002, 75% of soybean acreage, 71% of cotton, 32% of corn and 54% of canola acreage was planted with varieties developed through biotechnology. Because oil, e.g., cottonseed, corn and canola, and meal, e.g., corn, soy and cottonseed, from these crops is in many foods, the percentage of foods with one of these ingredients is high, by some estimates 75% of processed foods. SLIDE 12 Of the large acreage GE crops, only GE cotton is grown in large acreage in CA and not to my knowledge in Mendocino County.
Other smaller acreage crops have been genetically engineered, including grapes, but these crops are confined to small-scale field tests (most £ 20 acres?). Some have been conducted in CA, but to my knowledge no field tests of GE grapes have been conducted in Mendocino County.
What kinds of small acreage crops have been grown commercially? SLIDE 13 In the early 1990's several fruit and vegetable products were commercially grown and entered U.S. (and some European) markets, FlavrSavr tomato, New Leaf Potato, high solids tomato, and Freedom Squash. They were taken off the market but not because of consumer acceptance issues. The only whole GE fruit or vegetable in the commercial market today is papaya, engineered for resistance to a virus that nearly destroyed the crop in Hawaii. SLIDE 14 There are currently no GE strawberry, asparagus or grape varieties in commercial production in California, although small-scale field trials have been conducted under the guidance of the USDA's Animal and Plant Health Inspection Service (APHIS). It is not believed that any GE grapevines are grown in Mendocino County, certainly none on University of California land.
What kinds of GE crops are being tested? SLIDE 15 Many of the varieties being developed in university labs focus on new disease protection strategies, strategies that will replace, or at least diminish, the use of pesticides. Examples include:
What Do Consumers Really Think?
While much media attention focuses on safety questions related to GE foods, when asked to identify food safety concerns, few (1 to 2%) U.S. consumers list "altered or engineered food" as a concern. SLIDE 16 Certainly there have been a number of food and environmental safety issues raised regarding GE crops and foods. These issues must be carefully addressed. SLIDE 17 But efforts to resolve them should be proportional to the risk and should not overshadow addressing issues more relevant to solving the safety problems raised.
What Are the Issues? Food Safety?
So what are some of the issues surrounding GE crops? There have been some food safety issues raised related to GE foods.
I want to start by pointing out that it is not true that the GE foods that we are eating today have not been tested for food safety. SLIDE 18 It is true that the companies conduct most of this testing, as occurs in the pharmaceutical industry, and these tests are then reviewed by federal agencies like the EPA and FDA. And this testing at present is voluntary. But the companies have the most to lose if they "screw up" - as occurred with Starlink corn, which cost the company at least $2 billion.
What kinds of tests are carried out? Nutrient equivalence testing is done to show that, for example, all vitamins, minerals, proteins, carbohydrates and fats are the same for the GE and conventional food. SLIDE 19 Testing for toxicity and the ability to cause allergies is also done. To my knowledge no GE food in the market today is unsafe for human consumption. SLIDE 20
Questions were raised about the possibility of Starlink corn causing allergies - the reason taco and tortilla shells containing Starlink corn were recalled back in 2000. SLIDE 21 Starlink corn had a protein to protect it from insect damage that was permitted by the federal regulatory agencies to be used for animal feed but not for human consumption. Subsequent tests of individuals claiming to have had an allergic reaction to a food following the scare indicated that none of them were related to Starlink. But because of the uncertainty and the publicity over this event, a number of African countries refused to accept US food aid. Importantly this problem did raise the issue of crop segregation, and caused federal agencies to take a closer look at their policies. SLIDE 22
Is the issue of food allergies limited to only the new GE foods? Let's take the example of the kiwi. SLIDE 23 When it was introduced into the U.S. in the 1970's it was not known to be a food allergen. Today it is known that some individuals develop allergies to the fruit. In fact some people have cross allergies to latex rubber that could result in severe anaphylaxis, and in some cases death. Should we have done decades of testing to predict this? A difficult question.
Another area of concern was raised in a recent letter to the editor. The letter stated, "If you want to understand the (GMO) issue, just take10 mice, divide them into 2 groups. Feed one GMOs, and the other regular food. SLIDE 24 Then see the difference." Certainly none of the GE foods in commercial production today would have any adverse effect; humans have been consuming them since 1995. The writer is likely referring to some tests that were conducted in the mid 1990's by a researcher in Europe, Arpad Puztai. In his study rats were fed potatoes engineered with a certain protein from Snowdrop plants. He claimed to show evidence that the rats developed wounds in their stomachs as a result of the consumption of the genetically modified potatoes. But the broader scientific community found this particular study to be conducted poorly with too few animals used and inadequate controls; it left researchers unable to draw firm conclusions. This particular food should be re-investigated but it should be noted that this was not a product in the market nor was it intended to be.
What Are the Issues? Environmental?
I would like to focus my attention on issues I think are of interest to Mendocino county residents.
Movement of Genes into Wild Relatives. SLIDE 25 Could the passage of genes from GE crops to weed species lead to the development of a "superweed", one that does not respond to herbicides? Certainly the passage of genes from plant to plant will happen. In the U.S. major crops like soy, corn and cotton do not have wild relatives, but other crops like canola, sugarbeet, sunflower, rice and oats do have wild relatives and in some cases these relatives are control problems.
So is it possible that a trait could escape? Yes, it is likely. Could this be a problem? It is dependent on the trait and the characteristic it confers on the wild relative.
Let's look at red rice, which can contaminate and reduce the value of cultivated rice. SLIDE 26 The movement of gene for Vitamin A enhancement from red rice to cultivated rice would have little effect. On the other hand, movement of herbicide tolerance would make it impossible to control red rice - with the herbicide used against the plant with the resistance gene. It would not create a superweed, one that would not respond to herbicides, but it would require that farmers return to practices used before the introduction of these varieties.
Should we be concerned about the use of genes from other organisms, like the bacterial Bt gene? Again it is dependent not so much on the source of the gene, but on what that gene will do. Can we be assured that no unintended effects will occur? No, just as we can't be assured that some insect and weed control methods used in conventional and organic farming will not have adverse effects. We need to be mindful of the consequences on the environment of what we do.
SLIDE 27 What about movement of genes in areas of plant diversity. Again the impact should be judged on a case by case basis. In areas of cultural diversity, crops with certain traits should not be released. Or the plants should be engineered to prevent passage of the trait to wild relatives. An example of genes escaping in an area of cultural diversity was raised by a report that Bt genes escaped into landraces of corn in Mexico, an area of cultural diversity for this important crop.
Movement of Engineered Genes into Organic Crops
SLIDE 28 Another possible impact of gene movement involves the passage of genes to organically grown crops. In the U.S. federal policy developed by organic farmers themselves states that GE crops cannot be designated as "organic". Therefore, although genes have moved from conventional crops to organic crops for years, movement of engineered genes from conventionally grown plants to organic plants can cause problems for organic farmers.
SLIDE 29 But will organic farmers lose their certification if pollen from GE crops drifts onto organic plants and cross-pollinates? According to the Organic Supervisor for the California Department of Food and Agriculture, the only time when an organic farmer will lose certification is if he/she intentionally grows GE crops and they contaminate his/her organic crops.
SLIDE 30 The National Organic Program regulations speak to the issue of "GMO contamination" of organic crops by genetic drift. "This regulation prohibits the use of excluded methods [which include GMOs] in organic operations. The presence of a detectable residue of a product of excluded methods alone does not necessarily constitute a violation of this regulation. As long as an organic operation has not used excluded methods and takes reasonable steps to avoid contact with the products of excluded methods, as detailed in their approved organic system plan, the unintentional presence of the products of excluded methods should not affect the status of an organic product or operation."
However, if a certifying agent suspects that an organic product came into contact with prohibited substances or were produced using excluded methods, the agent can call for testing, which under certain conditions could result in the product not being considered "organic." (National Organic Standards, subpart G, Administrative, sections 205.670 205.671). So, if a GE grape variety were grown near organically grown grape varieties, could this cause a problem? It is possible for pollen (male cells) from one plant to fertilize the eggs (female cells) of another plant, because of bees, and sometimes wind. But, according to the Organic Supervisor for the CDFA, if this occurs by accident, the grower will not lose his organic certification and can sell his product as organic.
Increased Herbicide or Pesticide Usage. Another environmental concern relates to the potential for GE crops to have detrimental effects on the environment by increasing herbicide or pesticide usage or creating long-lived residues in the soil. In the first instance, most current data suggest the opposite, that so far the new GE crops have not led to an increase in pesticide use in active ingredient per acre. Based on several years of data, a strong case can be made for decreased pesticide usage in cotton.
A recent report by Charles Benbrook states that there is an increase in herbicide use for some herbicide tolerant GE crops, but other studies differ, perhaps due to differences in calculation methods or to the particular situation analyzed.
Creation of Weeds Resistant to Herbicides Certainly it is true that the use of certain herbicides has increased, the ones to which the GE crops are engineered to resist. In general these are more environmentally friendly herbicides but the overuse of single pesticides is likely to lead to, and already has led to, the development of herbicide resistant weeds. Was this surprising? Perhaps to some, but I think it proves again that overuse of a particular herbicide can render a new chemical or technology useless. Will this situation create an ecological disaster? Not likely. Other perhaps less environmentally friendly herbicides can be used, but it will be a problem for companies developing the crops and farmers using them!
SLIDE 31 For more information, scientific references and a copy of the talk and slides, visit the Biotechnology Information, Scientific Database and Resources sections of ucbiotech.org
