   Transgenic Technology in Crop Plants - February 10, 1999 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Human beings have been genetically altering plants for at least 10,000 years. When one crop variety had a desirable trait, it was crossed with another variety with a desirable trait and the resulting seed often showed improved characteristics. Today, plants are genetically altered by inserting genes from completely different species. A gene is a segment of a DNA molecule that codes for a specific protein. These proteins can express themselves in many different ways: flower color; oil content in seeds; cold tolerance; disease resistance; etc. The first successful gene transfer was from a human to a fertilized mouse egg. It soon progressed from transgenic mice to transgenic cattle, sheep, pigs, and crop plants. Bacillus thurengiensis (Bt) is a naturally occurring bacterium that is produced in large quantities and commonly sprayed on crops as an "organic" insecticide. When a hungry butterfly, moth, or beetle larva feeds upon a treated plant, the bacteria destroys its gut and death follows. In the early 1980's, scientists cloned the first (Bt) gene. This created the potential for the gene to be inserted into any crop plant and for natural resistance. Bt crop plants are now commonplace on many farms. Last year, 2.8 million acres of Bt cotton were grown in the United States. I think that most people would agree that the use of transgenic technology has societal benefits. Transgenic Bt crops can greatly reduce amounts of chemical pesticides entering the environment. However, control is not usually 100% effective. Corn earworms and bollworms are serious cotton pests and show some resistance to Bt. Additional pesticides are often needed to control these pests. Some environmental groups also fear the Bt gene could accidentally be introduced into native plant species. If this occurred, it could potentially take away an insect=s native food sources. Bt-transgenic varieties of corn and potatoes are also commercially grown. Numerous others are currently under development including rice, soybeans, broccoli, lettuce, walnuts, apples, and alfalfa. There are also transgenic genes for herbicide resistance. Millions of acres have been planted to Roundup Ready corn, cotton, soybeans, and potatoes. Monsanto (the manufacturer of Roundup) developed these transgenic crops. The overall purpose is to maximize production and minimize competition from weeds by allowing spraying of both weeds and crop plants with Roundup. The weeds are killed and the crop is left undamaged. By the way, Monsanto is also the world's second largest seed company. Transgenic seed is much more expensive to produce than non-transgenic seed. Conversely, we enjoy, either directly or indirectly, the benefits that these advanced technologies bring. There are some that argue that by transferring genes we are decreasing the natural diversity that exists in crop plant populations. Others argue that we are increasing the genetic diversity far beyond what nature could without human assistance. The latest technological advance is not transgenic, but an antibiotic that is sprayed on seeds prior to delivery. The resulting plant grows and produces a crop, but all of the embryos within the seeds produced by that crop are killed by the treatment. It is being called "Terminator Technology." It was designed by a partnership between USDA and Delta & Pine Land (a major cotton seed producer) specifically to protect proprietary products. Patents for the product are currently being applied for in 78 different countries. A Canadian organization, Rural Advancement Foundation International (RAFI) is working to inform the public and block the usage of Terminators. They argue that Third World countries need to have the ability to collect, save, and replant seeds for subsistence farming. They estimate that 1.4 billion people worldwide are reliant on their ability to save seed and breed their own crops. Some scientists also fear that the Terminator trait can be carried by pollen making seeds of non-target species sterile also. I think we all owe it to ourselves to become better informed about these issues. On a lighter note, I think the Backyard Gardeners will still plant their old reliable vegetable varieties, use Bt to control cabbage worms (applied directly to plants not transgenically), and maybe even save some seed for next year. The University of Arizona Cooperative Extension has publications and information on integrated pest management and vegetable varieties that are successful in Yavapai County. If you have gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |