Bt Corn as GMO - Essay Example

? Bt Corn TEACHER                 Bt Corn Bt corn is a genetically-modified organism or GMO, which means that its genes have been altered in some way in order to produce a better variety and that its genetic material is derived from another organism (Peel, 2001). As a set of nucleotides, the corn gene is a “specific sequence of nucleotide bases” that encode for constructing proteins, and this corn gene is where the Bacillus thuringiensis or Bt gene will be transferred (Peel, 2001). Before the Bt gene is transferred to the corn gene, it has to be “identified, isolated and cloned,” and its mRNA is isolated and used as a template to replicate the DNA and synthesize a complementary DNA or cDNA strand of the Bt bacterium (Peel, 2001). This cDNA strand is then isolated and cloned or duplicated for the purpose of transformation into another species and this transformation process is made possible with the help of the bacterium known as Agrobacterium tumefaciens (Peel, 2001). This particular bacterium infects specific woody dicotyledonous plant species, where certain parts of the Agrobacterium circular DNA known as Ti plasmid can insert themselves into the host plant’s cell (Peel, 2001). The host plant, which is the corn plant in this particular experiment, then expresses the Bt gene (Peel, 2001). If this particular transformation process is not opted for, then the gene gun can be utilized. The other transformation process is the use of gold particles and coating them with target genes, such as Bt genes in our example (Peel, 2001). Using a gene gun, the genes are shot into the single cells of the corn plant without the help of the Agrobacterium in a process known as particle acceleration (Peel, 2001). Now that the Bt genes are already incorporated into the corn plant, a series of tests should confirm the potency of the bacterial gene. Plant tissue culture is the next step. Individual cells of the corn plant are obtained for culture and are subjected to the transformation process, which basically involves the elimination of non-transformed cells using a method that involves the use of selectable marker genes (Peel, 2001). The cultured corn plant cells are then treated with herbicide or antibiotic, and whole corn plants called Bt corn plants are then grown from the seeds of those cultured cells that eventually survive (Peel, 2001). If the Bt corn plant expresses the trait even after several generations using laboratory techniques, then it is believed to be stable and can now be bred using conventional agricultural methods and the final test would be for it to be able to stand environmental conditions (Peel, 2001). The process of transformation of the corn gene into the Bt corn gene involves a crucial intermediate step where, before the Bt gene is inserted into the corn plant, it is first modified with promoters that would later on be recognized by the corn plant itself (Peel, 2001). This step and particularly these promoters is most crucial to the development of the toxic properties of the Bt corn plant. Because of these promoters, Bt corn “encodes crystalline proteins from the bacteria that are responsible for larvae toxicity” (Peel, 2001). Upon the Bt corn being eaten, these crystalline proteins, or Cry proteins, will bind to the insect’s midgut and cause a water imbalance that will eventually burst the cells and kill the pest (Peel, 2001). There are currently two types of promoters used in developing the Bt corn plant – the CaMV35S promoter and the PEP carboxylase promoter. The former expresses the toxicity of the Cry proteins in all plant tissues including the photosynthetic parts as well as the ears, roots and tassels, thus killing all insects that subsist on any part of the plant (Peel, 2001). On the other hand, the PEP carboxylase promoter, due to its exclusive affinity to cells that actively manufacture photosynthetic proteins, expresses the toxic properties of the crystalline proteins only in the photosynthetic parts – the stems and the leaves, thus not killing insect pests that subsist on the tissues of the roots, tassels or ears (Peel, 2001). Moreover, multiple Bt genes can target different species of insect pests in different types of crops, including corn (Peel, 2001). Bt corn, due to its toxic properties, has successfully eliminated huge populations of the European corn borer, which is the number one insect pest that infests corn, thus offering a “sound economic return” in the United States from 1988 to 1995 (Witkowski et al., 2002). Moreover, agricultural experts believe that “if 50% of the corn acreage is planted to Bt corn, then the corn borer population in the area could be reduced by 50%” (Witkowski et al., 2002). This means that Bt corn is indeed effective in reducing the population of the European corn borer and thus protecting even naturally grown corn. Moreover, Bt corn does not affect beneficial insect species such as honey bees, pirate bugs, spiders and parasitic wasps (Witkowski et al., 2002). However, the impact of the Bt corn plant on the individual agricultural ecosystem has not been without controversy. Despite the benefits that the Bt corn plant has had in eliminating huge numbers of the European corn borer, there is always the question of whether this particular species of insect pest can eventually develop resistance to the toxin of the Cry proteins (Witkowski et al., 2002). The solution is simply proper agricultural management and one that involves killing all European corn borer larvae that have no genes for resistance or those with only one copy of the resistance gene, in case these types of larvae develop (Witkowski et al., 2002). Another principle of the resistance management plan involves producing “an overwhelming number of susceptible moths to every resistant moth” (Witkowski et al., 2002). Eventually, the interbreeding of these two subtypes of moths, on the condition that at least 20% to 30% of the moths are susceptible, will eventually yield the susceptible variety (Witkowski et al., 2002). Another issue facing Bt corn is its suspected harmful effect on the monarch butterfly species, although it is confirmed that the transgenic crop does not produce any “significant risk” to these beautiful butterfly species (“Q&A: Bt Corn,” 2004). Nevertheless, one Bt corn variety known as event-Bt 176 was found to have a “negative” effect on the monarch caterpillars even with pollen concentrations of as little as 10 grains per square centimeter, but this variety has been replaced with other less harmful types (“Q&A: Bt Corn,” 2004). In the broader ecological ecosystem which involves human beings, Bt corn still has a questionable reputation as there are “fears of human health” although experts have already considered Bt corn “potentially safe for human consumption” (Hall, 2011). Nevertheless, there is a “lack of conclusive evidence” as to the long-term effects of Bt corn on human health (Hall, 2011). Thus, there is indeed a great necessity for long term research when it comes to this aspect. Since the broader ecological ecosystem also concerns the environment, the role of Bt corn is also questionable since there is but insufficient information on the actual ecological risks posed by the genetically modified crop (Hall, 2011). Long-term research is therefore indispensable in order for experts to be able to come up with conclusive evidence regarding the true benefits of Bt corn as well as to dispel fears and concerns associated with its production. References Hall, H. (2011). “Bt Corn: Is it Worth the Risk?” Retrieved Nov. 19, 2011 from the Science Creative Quarterly: http://www.scq.ubc.ca/bt-corn-is-it-worth-the-risk/ Peel, M. D. (2001). “A Basic Primer on Biotechnology.” Retrieved Nov. 19, 2011 from North Dakota State University: http://www.ag.ndsu.edu/pubs/plantsci/crops/a1219w.htm “Q&A: Bt Corn and Monarch Butterflies.” (2004). Retrieved Nov. 20, 2011 from the United States Department of Agriculture Agricultural Research Service: http://www.ars.usda.gov/is/br/btcorn/ Witkoswki, J.F., Wedberg, J.L. & Steffey, K.L. (2002). “Bt Corn and European Corn Borer.” Retrieved Nov. 19, 2011 from the University of Minnesota Extension: http://www.extension.umn.edu/distribution/cropsystems/dc7055.html Read More