Genetically Engineered Crops - Essay Example

Genetically Engineered Crops Introduction Over the last two decades, the life sciences industry has made enormous investments in biotechnology research and development; thrown tremendous energy into getting its genetically engineered (GE) crops approved, patented, and commercialized; and lobbied U. S. farmers and food producers to use them. For their part, the U. S., British, and other governments that envision the biotechnology sector as the wave of the future, and as a means of augmenting their national competitiveness, have strongly supported the industry and its efforts to commercialize (and normalize) these new technologies. They have devoted considerable sums of money to biotechnology research (Gottweis 1998), taken significant strides to deregulate the industry (Wright 1994), and sought to promote the spread of U. S.-style intellectual property rights in the World Trade Organization. The U. S. government in particular has also promoted the dissemination of agricultural biotechnology in developing countries through the U. S. Agency for International Development. With so much economic and political muscle propelling them, it is not surprising that GE crops hit the ground running when they came onto the scene in the mid-1990s. But what is surprising is that the rapid growth in GE crop deployment has been matched by an equally remarkable (and perhaps historically unprecedented) proliferation of citizens voices challenging the biotechnology industry on economic, environmental, cultural, and moral grounds. Indeed, long before transgenic crops made their way to the market, individuals and groups concerned about the dissemination of these new technologies were already questioning their safety, utility, and necessity. Advances in genetics have reached a stage where breeding schemes can now be augmented with the use of a number of technologies. Commercial breeding programs have and will continue to evaluate and invest in research that considers the prospects to either change or refine the in situ gene-to-phenotype system. From the 1990s, transgenic methods have been applied to key traits. Commercial transgenic hybrids have been developed for traits where there is a simple gene-to-phenotype relationship. At this early stage of technology development it is tempting to conclude that transgenic solutions will only be applicable for trait targets under simple genetic control. However, this view is not accurate. Conventional genetic improvement of resistance to insect pests was viewed as a traditional complex trait problem before the widespread use of trans-gene sources of resistance to insect pests. Organization of Genomics Efforts Only over the last decade has the scientific community developed and had access to the range of molecular tools that provide the technological foundation that will be necessary to understand (i) the genetic architecture of the trait combinations we seek to manipulate, (ii) the nature of the genetic changes that were brought about by phenotypic selection, (iii) the power that can be attained in a breeding strategy (molecular and conventional) to achieve directed genetic changes that manipulate the trait phenotypes we seek to improve, and (iv) the limits that will ultimately be faced in using genetic technologies to make robust changes to plant phenotypes that improve the sustainability of agricultural systems. Much of the genomic technological advancements used in plants were developed to meet the needs of the human genome effort. In most cases the application of these DNA-, RNA-, and protein-based technologies to study plant genomes has been straightforward. To take advantage of the opportunities that these genomic technologies provide to plant breeding, plant genomics efforts over the last decade have been heavily focused on plant specific gene discovery, gene function knowledge creation, and organization of the heterogeneous data sources that have emerged across the scientific community. Creating a Molecular Breeding Focus Today the concept of commercially successful molecular breeding is multifaceted and should be viewed as such. At its current stage of development as a proven breeding methodology, the term "molecular breeding" is a collective descriptor of the heterogeneous efforts, challenges, and opportunities being investigated to enhance the short-term and long-term success of the systematic procedures used to improve trait phenotypes by directed manipulation of the genotype at the DNA sequence level. At this time, molecular breeding is not an identifier of a single general breeding approach in the same way that "pedigree breeding" is such an identifier. Thus, many different breeding approaches are considered under the title of molecular breeding. Two major components are in use today: (i) direct movement of genes between individuals by a range of transgenic approaches and (ii) development of associations between inter-individual DNA sequence variation and trait phenotypic variation in combination with the design of DNA based prognostics that can be used in high throughput systems as a component of a breeding program. The feasibility and the range of successful outcomes from both approaches are being enhanced for a range of traits by greater fundamental knowledge of plant genome organization and the functional properties of genes (Wright 1994). Improving a Breeding Strategy The concept of evaluating alternatives and building on the strengths of an incumbent strategy is not new to plant breeding. The overriding motivation for considering molecular breeding strategies in place of conventional phenotypic-pedigree-based breeding strategies is that molecular-based selection does or with appropriate development will provide advantages over phenotype-based selection. Often many hidden assumptions are made in the theoretical discussions of the advantages that can be realized from molecular breeding strategies. One assumption that is often difficult to consider fully is the complexity of the genetics that the current strategy faces. Overly simplified genetic models can often give an associated overly optimistic assessment of the benefits, or in some cases lack of benefit, to be expected from an alternative strategy. Ultimately, validation by measuring realized benefits in situ are necessary. Because of the complex stochastic nature of the genotype-environment systems that breeding programs operate within, it has been resource intensive and difficult to demonstrate the advantage of one breeding strategy over another. A major difference between academic and commercial evaluations of molecular breeding strategies is the greater need by the commercial programs to make as many of the hidden assumptions that underlie the potential advantages and disadvantages as visible as possible for direct consideration. These advantages may come in the form of (i) reduced costs for achieving a given level of phenotypic improvement, (ii) improvements in the accuracy and precision with which we can make phenotypic changes, (iii) step-change improvements in phenotypes that were not previously accessible with comparable research investments into conventional breeding methods, and (iv) the identification of industry game-changing technologies for complex genotype-environment systems. By emphasizing the need for a demonstrable advantage at the level of the commercial viability of breeding program outcomes, the criteria for success are set at a much higher level than would be the case if all that was required was a demonstration that genotype-based improvement of the phenotype, via manipulation of DNA sequence, was feasible. This is much the same process that was used by previous Pioneer breeders in judging the merits of alternatives to and refinements of the conventional pedigree-breeding program. Ultimately, for commercial breeding programs, the success of any alternative breeding strategy is based on the value that can be gained by all stakeholders from the improved phenotypes and the costs of attaining and maintaining these improved phenotypes. Therefore, the challenge is to outperform the current breeding strategy for a wide range of situations. The range of approaches must work for the important traits, which will inevitably differ in genetic complexity. It is difficult to conduct comprehensive empirical evaluations of alternative breeding strategies for a large number of scenarios. An alternative approach is to use computer simulation (Mann, C.C., and M.L. Plummer. 2002). The more effective the current breeding strategy the more difficult will be the challenge to outperform the incumbent strategy and demonstrate the advantages. As with most difficult challenges, the paths to improvement are many and any commitment to molecular breeding strategy development will be an iterative process. The commercial molecular breeding strategies we see today represent first or second cycle iterations of some of the potential paths to implementing molecular breeding strategies. These may be more accurately referred to as molecular enhanced breeding strategies, which apply molecular technologies around what are still predominantly large pedigree breeding strategies. Not content to tinker only with traditional agricultural crops and domestic animals, bioengineers are venturing farther a field to genetically alter a variety of plants and animals from forests, meadows, and aquatic habitats. Some of these GMOs blur the distinction between cultivated and uncultivated, or between domesticated and wild, but these transgenic creatures and organismal clones, however categorized, represent further evidence of the wide range of taxa, as well as traits, that can be genetically manipulated using recombinant DNA methods. The extension of genetic engineering beyond factories, croplands, and barnyards raises many additional hopes and fears, especially with regard to the environment. Might genetic engineering experiments “in the wild” invite ecological disasters? Or, at the other possible extreme, could some of the new genetic discoveries and GM products actually help the planet to recover from insults of earlier technological endeavors (such as energy extraction, mining, farming, and commercial fishing) that often generated toxic wastes or otherwise damaged natural ecosystems? Most of the contemplated GM projects relating to the environment are only in the early phases of research and development, so definitive answers to such questions will take some time to emerge from direct experience. In the meantime, given the general dearth of critical scientific evidence in this neophyte field, plausible arguments pro and con can be made regarding many prospects for outdoor genetic engineering. As is typical of GM technologies applied to nature, simple solutions can be elusive, and case- by -case analyses are required. Trees provide greater scientific challenges for bioengineering than do most herbaceous plants. First, the genomes of most tree species are poorly characterized at present, leaving open many basic questions about their gene structures and functions. Second, relatively few trees proliferate clonally in nature, so even if an individual tree is engineered successfully, subsequent propagation of its trans-genes remains problematic. Third, trees usually take at least several years to mature, making it harder to monitor the multigenerational effects of any genetic tinkering (Dinus, Payne, Sewell, Chiang, & Tuskan. 2001). Undaunted, some forest scientists are forging ahead with plans to redesign trees for a variety of genetic features of potential commercial significance. By the year 2002, the Animal and Plant Health Inspection Service (APHIS) of the USDA had received (and often approved) nearly 150 applications for outdoor field tests of GM trees, while dozens more such experiments are being conducted in at least 15 other countries. Many of these are private-industry ventures, proprietary, and rather secret. At the APHIS website, for example, the phrase “confidential business information” is all that commonly appears in the column listing the gene and the species of tree being studied (National Research Council. 2002). Other preliminary GMO ventures have received wider publicity. A case in point involves attempts to genetically alter the lignin content of pulpwood trees. Lignin is a hydrocarbon substance that helps give tree trunks their stiffness, and industries must go to great lengths to remove it during the conversion of wood to pulp and paper. During the process, paper mills use huge amounts of highly toxic chemicals that are a serious source of environmental pollution. A 1988 study from North Carolina State University estimated that even a 5% reduction in the lignin content of pulpwood trees would appreciably lessen the need for these harsh chemicals and also save the paper industry about $100 million annually in processing costs (National Research Council. 2002). Clearly, the economic and environmental incentives to engineer pulpwood trees for reduced lignin content are considerable. Toward that end, researchers produced a transgenic strain of aspen trees with 45% less lignin than their wild brethren. They manipulated genes in a biosynthetic pathway in such a way as to partially block the trees natural lignin-making capacity. Remarkably, the GM trees remained sturdy and actually grew faster than normal. The structural integrity of the trees seemed to be maintained in part by a compensatory increase in cellulose, another carbohydrate that contributes to the natural tensile strength of aspens cell walls. Similar attempts now are underway to genetically engineer reduced lignin content in pine and eucalyptus trees, two traditionally popular sources of pulpwood. Critics point out potential drawbacks to genetically engineered trees such as these, especially if they someday were to be planted on commercial scales. Trees live far longer than most biotech food crops, so any negative long-term ecological impacts will be harder to assess and counter. Additional ecological questions arise: With such genetically altered features, how will the trees themselves fare in nature? For example, might low lignin trees be more susceptible to insect attacks? Might the trans-genes transfer via hybridization to other forest species and genetically modify them in undesirable ways? More generally, might not the introduction of GM trees further promote monocultural tree plantations that are little more than biological deserts? Already, vast uniform stands of non-transgenic pulpwood pines, planted, for example, in coastal regions of the eastern United States, are biotically impoverished, containing few other forms of life. On the other hand, in a recent analysis of transgenic poplars grown experimentally for four years at sites in France and England, researchers concluded that lignin-altered trees remained healthy and interacted normally with insects and soil microbes. These GM trees also grew at standard rates, required smaller amounts of pulp-processing chemicals, and still yielded high-quality pulp (National Research Council, 2002). Genetic engineers argue that in addition to reducing papermill use of caustic chemicals, GM trees can provide other environmental benefits. They suggest, for example, that forests engineered for higher productivity will enhance the efficiency of wood-product industries and thereby lessen harvesting pressures on native stands. Globally, timber products support an annual $400 billion industry, with demand for pulp and paper alone estimated to increase by about 50% in the next two decades (Mann, & Plummer. 2002). Some analysts contend that bioengineered trees offer the best way to meet growing demands for wood products without further decimating bio-diverse natural woodlands. For economic and biological reasons, forest genetic engineering has not yet proceeded in the frenzied, profit-driven atmosphere that accompanied the promotion of faster growing GM crops. This may be a blessing. Without the overwhelming pressure and capacity to make a fast dollar from slow-growing trees, societies and the sciences they support will have more time to process wise judgments about how GM pulpwood forests might affect both the economy and the environment. Conclusions “Genetic engineering” can be a misleading term if taken to imply undue analogies to physical engineering. When geneticists tinker with the genetic makeup of plants, animals, or microbes, the outcomes can be far less predictable than when a mechanical engineer builds a house, a bridge, or a dam. Each individual organism changes continually during its development, thus posing an ever-shifting physiological milieu for genetic manipulation. At the population level also, nothing remains static, but rather evolves, often in partial response to any genetic alterations themselves. So, too, will other species evolve with whom GMOs interact. The net results are ever-changing and varied responses to genetic manipulations and levels of temporal unpredictability that far surpass what physical engineers encounter. The first three decades of genetic engineering often have been characterized by inappropriate linear thinking in several regards. First, near-term profits have driven much of the commercial enterprise, with limited regard for diffuse or longer term societal and environmental ramifications of genetic manipulations. Indeed, some companies have shown a remarkable disregard for public sensibilities, and a general hubris has hurt their own cause. Second, a common tendency has been to suppose that a given trans-gene will affect only the specific organismal trait in question, such as insecticide resistance, or the capacity to produce a pharmaceutical drug. But living creatures are complex beings with multitudinous metabolic and physiological demands underlying successful survival and reproduction. Biological intuition predicts, and empirical experience confirms, that specific genetic traits seldom can be altered without precipitating collateral effects. Cascades of ancillary or compensatory impacts on the transgenic organisms often become apparent only after the fact. The phenomenon of yield drag in transgenic crops is one familiar example. Side-impacts of inserting growth-hormone genes into fish are another. The prospect of unanticipated side effects must also be borne in mind by anyone contemplating the genetic modification of humans. Third, a frequent tendency has been to underemphasize, if not neglect, the extended consequences of releasing GMOs into environments. Just as a trans-gene inserted into a genome can have unforeseen effects on the GM organism itself, a transgenic strain introduced into the environment can have unintended impacts on the ecology and evolution of interacting species. Due to such community-level responses, plausible outcomes and contingency plans should be considered a priori, as well as monitored after a GM strain has been unleashed into nature. Seldom have either been done with full vigor and effectiveness, despite various regulatory procedures in some countries. A great irony is that many of genetic engineerings greatest promises lie in correcting problems created by the cutting-edge technologies of earlier eras. For example, GM microbes and plants someday may be used widely to decontaminate toxic waste sites, rejuvenate tainted soils, and cleanse polluted waterways of poisonous chemical effluents from manufacturing. The promise of genetic engineering also differs from that of nuclear physics in important ways. Whereas the primary commercial use of nuclear energy lies in power generation, genetic engineering can find application in a vast range of activities, from agriculture and manufacturing to medicine and environmental remediation. Furthermore, whereas nuclear fission is inherently dangerous to life, many, but certainly not all, of the contemplated uses of genetic engineering are quite safe and benign. Thus, over the longer term, genetic engineering may yet blossom in additional directions that will bring huge and lasting benefits to mankind. Reference: Dinus, R.J., P. Payne, M.M. Sewell, V.L. Chiang, and G.A. Tuskan. 2001. Genetic modification of short rotation popular wood: properties for ethanol fuel and fiber productions. Crit. Rev. Plant Sci. 20:51–69. Mann, C.C., and M.L. Plummer. 2002. Forest biotech edges out of the lab. Science 295:1626–1629. National Research Council. 2002. Environmental Effects of Transgenic Plants. National Academy Press, Washington, DC. Gottweis, H. 1998. “The Political Economy of British Biotechnology.” In Private Science: Biotechnology and the Rise of the Molecular Sciences, ed. A. Thackray. Philadelphia: University of Pennsylvania. Wright, S. 1994. Molecular Politics: Developing American and British Regulatory Policy for Genetic Engineering 1972–1982. Chicago: University of Chicago Press. Read More