   Genetically Modified Crop Update - December 12, 2007 Jeff Schalau, Associate Agent, Agriculture & Natural Resources, Arizona Cooperative Extension, Yavapai County Scientists working on genetically modified crops are often vilified by the media for killing butterflies and creating Frankenstein-like plants that could take over the earth. While caution and ethical conduct are necessary components of scientific discovery, we may also consider some of the societal benefits these discoveries can produce. The ethical debate surrounding genetically modified organisms (GMOs) will undoubtedly continue, but each person should become informed and decide for themselves. Let’s look at two genes that originated from bacteria and have been “spliced” into plant genetic material. Bacillus thuringiensis (also called Bt) is a soil dwelling bacteria has been known since the early 20th century to control butterfly, moth, fly, and beetle larvae. It works by degrading the gut wall of the larval stage of the insect with little or no effect on humans, wildlife, pollinators, and most other beneficial insects. Many home gardeners and farmers use products containing Bt to control plant-eating insect larvae. These products work fairly well but are quickly degraded through environmental exposure and must be applied more often than other insecticides. More recently, crop researchers have isolated these toxin-making genes and inserted them into corn, cotton and other crop plants to make them less palatable to insects and also reducing the farmer’s reliance on synthetically produced pesticides. This technology was highlighted by the national media when it was reported that monarch butterflies would be killed by the “toxic” pollen produced by Bt corn plants. This research was found to be flawed and the claim was later refuted by subsequent research. Even so, this story persisted and seemingly provided ample fuel against developing and utilizing GMO crops. The ongoing concern about Bt-modified crops is that of pests developing resistance to Bt from continual exposure. Where Bt-modified crops are used, insects that feed on the genetically modified plants may survive exposure to the Bt toxin and breed with other potentially Bt-resistant individuals to create offspring that are even more resistant than their parents. The current practice used to minimize Bt resistance is to plant non-Bt-modified crops in adjacent fields so that insect breeding is less likely between Bt exposed survivors. This strategy still has a high probability of increasing Bt resistance in pest insects over time. Mexican researchers at the National Autonomous University of Mexico in Cuernavaca are collaborating with University of Arizona researchers to create a Bt toxin that works more efficiently therefore reducing the chances of pest survival and hence, a resistant population. This new Bt toxin has already been demonstrated to effectively kill Bt resistant pink boll worm populations. Whether you agree or disagree with the concept of GMOs, inserting Bt genes into crop plants reduces synthetic pesticide applications on these crops leading to improved environmental quality for all. Another more recent development in genetically modified crop research could potentially lead to increased drought resistance in crop plants. A gene called IPT, also borrowed from a bacterium, codes for an enzyme that can delay stress-induced leaf drop in plants. Eduardo Blumwald at the University of California, Davis has created tobacco plants genetically engineered to express IPT. These tobacco plants stayed green during a lab test when researchers stopped watering them for 15 days. The IPT plants also did well on skimpy rations, achieving at least 85 percent of the usual yield when the researchers cut the water supply to 30 percent of normal. Blumwald says the tobacco work shows that the idea has promise, and he hopes to see it tested in food crops such as wheat and tomatoes. The tradeoff comes when drought conditions are not present leading to a lower yield in the drought resistant varieties. I’m not trying to sell you on GMO crops. However, I do like to learn about recent scientific discoveries and share them with readers. Much of the above information was excerpted from the weekly magazine, Science News (more information at www.sciencenews.org). It’s a great way to keep current on scientific breakthroughs without having to wade through complex journal articles. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at cottonwoodmg@yahoo.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |