The art of recognizing valuable traits is important in plant breeding. Breeders scrutinize their fields carefully and travel to other countries searching for domesticated varieties or wild relatives with desirable traits. Such traits occasionally arise spontaneously through mutation. While most breeders cross-pollinate plants of a single species, some breeding methods rely on hybridization between two distant species of the same genus. Less commonly, hybridization is carried out on members of two different genera.
Plant biotechnology has two meanings. In the general sense, it refers to innovations in the use of plants, or substances obtained from plants to make products of use to humans. In a more specific sense, biotechnology refers to the use of genetically modified (GM) organisms in agriculture and industry. Unlike traditional plant breeders, modern plant biotechnologists, using genetic engineering techniques, are not limited to the transfer of genes between closely related species or genera. In traditional breeding, breeders were not able to insert a desired gene into their domesticated plants through hybridization and cross-breeding methods. With genetic engineering, however, such gene transfers can be done more quickly, more specifically, and without the need for intermediate species.
The commercial use of transgenic crops has been one of the most dramatic examples of rapid technology adoption in the history of agriculture. These crops include varieties and hybrids of cotton, maize, and potatoes that contain genes from the bacterium Bacillus thuringiensis. These “transgenes” encode a protein called Bt toxin that is toxic to insect pests but harmless to humans, greatly reducing the need for chemical insecticides. Considerable progress has also been made in developing transgenic crops that tolerate certain herbicides. Cultivation of these plants may reduce production costs by enabling farmers to “weed” crops with herbicides without destroying the transgenic crop plants. Researchers also engineered plants with enhanced resistance to disease and improved nutritional quality. Scientists also concluded that the use of plant biotechnology could reduce fossil fuel dependency. By utilizing the polymers in cell walls and breaking them down into sugars by enzymatic reactions, these sugars would be fermented into alcohol and distilled to yield biofuels. The use of biofuels from plant biomass would reduce the net emission of carbon dioxide. Whereas burning fossil fuels increases atmospheric carbon dioxide concentration, biofuels crops reabsorb by photosynthesizing the carbon dioxide emitted when biofuels are burned, creating a cycle that is carbon neutral.
Much of the debate about GMOs in agriculture is political, social, economical, or ethical and therefore reaches beyond the scope of Biology. However, let us take a look at the biological concerns about GM crops. Many GMO opponents worry that genetic engineering may inadvertently transfer allergens, molecules to which some people are allergic, from a species that produces an allergen to a plant used for food. So far, there is no credible evidence that GM plants specifically designed for human consumption have adverse effects on human health. In fact, some GM foods are potentially healthier than non-GM foods. Nevertheless, because of health concerns, GMO opponents lobby for the clear labeling of all foods containing products of GMOs. Many ecologists are also concerned that the growing of GM crops might have unforeseen effects on nontarget organisms. One laboratory study indicated that the larvae of monarch butterflies responded adversely and even died after eating milkweed leaves heavily dusted with pollen from transgenic Bt maize. Recent studies, however, have shown that the spraying of pesticides on the Bt maize is much more harmful to the nearby monarch population that the Bt in the maize population. Although the effects of Bt maize pollen on monarch butterfly larvae appear to be minor, the controversy has emphasized the need for accurate field testing of all GM crops and the importance of targeting gene expression to specific tissue to improve safety. However, the most serious concern raised about GM crops is the possibility of the introduced genes escaping from a transgenic crop into related weeds through crop-to-weed hybridization. The fear is that the spontaneous hybridization between a crop engineered for herbicide resistance and a wild relative might give rise to a “superweed” that would have selective advantage over other weeds in the wild and would be much more difficult to control. Prevention of transgene escape, however, have already been strategized, although the likelihood of creating a new destructive species of plant is possible.
In my honest opinion, I believe that the benefits of GMO crops outweigh the concerns. As listed above, GMO crops have many beneficial uses in reducing world hunger, increasing productivity, reducing fossil fuels, and improving the environment. However, I believe we should still take into consideration with the concerns surrounding the development of GM crops. We should be ready for potential threats that may or may not arise from GMOs. I also believe that just because GM crops dominate the markets, there is no reason to stop our society from embracing traditional breeding. Preservation of traditional values is a good thing, allowing us to explore methods that we have used before the introduction of biotechnology.
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