Genetically Modified Crops - Dissertation Example

? A literature review of Genetically Modified crops Introduction A genetically modified or GM crop is primarily used for agricultural reasons where single or multiple genetic coding for desirable characters are inserted into a plant through the process of genetic engineering (King 2003). These genes may originate from species of the same plant or of different species, while they may also originate from organisms that have no connection to the recipient crop. Plant genetic engineering as a mode for creating GM crops was developed during early 1980s, and commercially available GM crops were first seen in the market during mid-1990s. In 2008, GM crops were planted on almost 9% of the available farming land in different parts of the world (James 2008). According to The World Health Organization or WHO, genetically modi?ed organisms are “derived from organisms whose genetic material (DNA) has been modified in a way that does not occur naturally, e.g. through the introduction of a gene from a different organism. Currently available GM foods stem mostly from plants, but in the future foods derived from GM microorganisms or GM animals are likely to be introduced on the market. Most existing genetically modified crops have been developed to improve yield, through the introduction of resistance to plant diseases or of increased tolerance of herbicides” (WHO 2013). The technology used for creating GM organisms allows selective genes to be relocated from one organism into another of the same species, and between species that are non-related. Such processes are used for creating genetically modi?ed plants, which in turn produce GM food crops. The crop characteristics marked as desired for GM crops and aimed by genetic engineering are from those that are targeted by processes followed during conventional breeding. However, genetic engineering gives scope for direct transfer of genetic codes across different species owing to which characters that were earlier difficult to breed through natural processes, is now created easily under controlled conditions. Currently there are three types of traits clearly distinguished in GM crops. These comprise of the first-generation GM crops displaying vast improvements in agronomic characters, as for example, better resistance to diseases and parasites. Second-generation GM crops tend to show improved quality characteristics, as for example, increased levels of nutrient contents in the resulting food products. Third-generation crops tend to show characters with special productivity aimed at industrial or medicinal purposes (von Braun 2007). The potential benefits of GM crops are diverse. In the current context, that shows decreasing natural resources, it is important to maintain an increase in productivity values within worldwide agriculture for ensuring enough food availability and raw materials for a persistently increasing population (von Braun 2007). Various environmental benefits are also associated with GM crops. Besides these, technologies associated with the new seed technology have played significant role for increasing rural income and alleviating poverty levels in developing countries (Fan et al. 2005). Furthermore, GM crops that have greater nutritional values would help in the improvement of overall consumer health (Unnevehr et al. 2007). Despite these potential benefits, the creation and use of GM crops have raised strong opposition, especially in parts of Europe, while also spreading over to other countries through media messages, trade regulations, and activism by the various antibiotech groups (Paarlberg 2008). The primary issues concern potential health and environmental hazards, while reservations are also expressed on the possible negative social ramifications (Altieri 2001). As for example, many of the activists feel that rampant use of GM technology in the developing nations could result in undermining the traditional agricultural practice that is based on knowledge setups. With rising privatization in the arena of researches related to crop improvement and the recent conceptualization of intellectual property rights, there are increasing concerns about possible monopolization of the GM seed markets and profiteering at the cost of minor farmers (Sharma 2004). However, another major problem associated with transgenic crops is related to the safety assessment of the outcome of these crops, which is the new food variety. This problem is primarily based on the concept of “substantial equivalence,” with the following principle: “if a new food is found to be substantially equivalent in composition and nutritional characteristics to an existing food, it can be regarded as being as safe as the conventional food” (SOT 2003). This principal allows for the distinguishing the potential differences between the existing and new food products, which can be further researched as regards their toxicological effect (Kuiper et al. 2002). Thus, here the main question regarding genetically modified crops is: are there any toxicological effects of GM crops? Discussion History and current position of GM crops The first GM crop was developed in 1982, which was a tobacco plant with antibiotic-resistant traits (Fraley, et al. 1983). The first scientific trials of GM crops at an agricultural level took place in the US and France in 1986, when tobacco plants were developed that were herbicide resistant in nature (James and Krattiger 1996). In 1987, a Belgium based firm known as the Plant Genetic Systems first developed a genetically modified crop (tobacco) that showed traits of insect tolerance, which was achieved by expressing genetic coding for insecticidal proteins from the organism Bacillus thuringiensis or Bt (Vaeck et al. 1987). China was the first nation to use commercialized form of transgenic crops in 1992 (a virus-resistant tobacco) (James 1997). The first GM crop available for sale in the market was in 1994 in the U.S., which was the Flavr Savr tomato, with a greater shelf life (Bruening and Lyons 2000).  In 1995, Environmental Protection Agency declared Bt Potato as safe, which made it the first approved GM crop in the US. In 1995 other GM crops like Bt cotton (Monsanto), canola with different oil composition (Calgene), bromoxynil (herbicide) resistant cotton (Calgene), glyphosate (herbicide) resistant soybeans (Monsanto), (Bt) corn (Ciba-Geigy), and squash that was virus-resistant (Asgrow) received marketing approval in the US. In 2000, after the scientists developed ‘golden rice,’ GM crops with increased nutrient value came into existence for the first time (Ye 2000). The commercial use of GM crops, which started around mid-1990s, rapidly spread across the globe, both in, developed and developing nations. Records revealed that in 2008, almost 125 million arable lands were growing GM crops across 25 nations, and the top five countries having the largest areas of GM crops included the US (50%), Argentina (17%), Brazil (13%), India (6%), and Canada (6%) (James 2008). However, amongst members of the European Union (EU), GM crops are grown extensively only in Spain. Commercial application of GM crops in the EU remains limited owing to public disapproval and antagonistic rules and regulations. Currently, only some of the first-generation technologies are commercialized, where the dominating technology is that of soybean herbicide tolerance (HT), where reports show that it forms nearly 53% of worldwide GM crop grown in 2008, and accounts for almost 70% of the global soybean production (James 2008). HT soybeans are seen in US, Brazil, Argentina, and other Latin American nations. The second most dominant GM crop is maize, and in 2008, it accounted for almost 24% of total crop yield worldwide and 30% of worldwide GM area (James 2008). GM maize shows traits that include insect resistance and HT (Romeis et al. 2008). Bt maize is grown primarily in South and North America, though seen to extensively in Philippines and South Africa. Other prominent GM crops with large area shares include canola and cotton. In developing countries Bt cotton showing resistance to budworms and bollworms are more relevant and in 2008, India was seen to have the largest area growing Bt cotton, followed by China (James 2008). Other GM crops, such as HT sugarbeet and alfalfa, and virus-resistant squash and papaya have received approval in other countries and are grown in very small areas. Methods for developing GM crops Genetically modified crops are plants, whose DNA  has been changed using the process of genetic engineering to create species that can withstand harmful agents and pests, thus helping in the improvement of overall growth and development of these plants and elevating agricultural efficiency. A genetically engineered plant is developed in laboratories where their genetic makeup is modified by adding single or multiple genes to the existing genome using different genetic engineering methods. A majority of the GM plants are developed by biolistic method (also known as particle gun) or by transformation (mediated by Agrobacterium tumefaciens). Agricultural scientists, claim that crops altered using GM techniques have fewer chances of showing undesired alterations than traditionally bred crops (Catchpole 2005). In research, tobacco is the favored choice for genetic modification and serves as a model organism in genetic modification of plants, owing to well-developed methods of transformation, easy proliferation and well-researched genomes (Koornneef and Meinke 2010). In biolistic method, a specific DNA is attached to small particles of tungsten or gold that is then shot into a plant cell or tissue under high pressure (Klein et al. 1987). The particles that enter at a great speed manage to pervade both the cell membranes and walls. The DNA, which becomes separated from the bound metal then, is unified with the genome located inside the nucleus. This process has used successfully for many monocot crops, such as maize and wheat where the process of transformation via Agrobacterium tumefaciens fails to produce the desired effects (Shrawat and Lorz 2006). A primary disadvantage of this process is that there are chances of the cells and tissues facing damage owing to the high-speed particles (Klein et al. 1987). Agrobacteria, which are plant parasites in their natural form, have a capability to transfer genes, which gives a scope for creating another method for developing GM plants. In order to form a favorable environment, the Agrobacteria transfer their genes into their plant hosts, which produce large-scale growth of plant cells (Shrawat and Lorz 2006). The genetic code for this tumor growth is located on a circular, mobile DNA fragment known as plasmid (T-DNA). When Agrobacterium infects a plant, the former transfers this T-DNA to any random site within the genome, and in genetic engineering this bacterial T-DNA is replaced with the desired gene. Thus, we find the bacterium acts as a vector, allowing the transfer of foreign desired genes into plants (Shrawat and Lorz 2006). This genetic engineering technique works successfully for dicots, such as tobacco, tomatoes and potatoes. Agrobacteria transformation is less successful in crops like wheat and maize. Safety concerns on GM crops and toxicity studies Despite potential bene?ts of genetic engineering in producing GM crops to improve quality and reliability of the global food supply, issues have been raised from both public and scienti?c groups, as regards food and environmental safety of GM crops. Taking into view these safety concerns, different legislations and regulations are being framed for controlling and monitoring the development of GM crops. Taking into consideration the fact that different GM crops comprise of different genes that are transferred via different methods, WHO has implied that safety of individual foods must necessarily be assessed in a case-by-case basis. From an overall viewpoint, the safety assessment of GM foods as per the WHO guidelines would investigate: “(a) direct health effects (toxicity), (b) tendencies to provoke allergic reaction (allergenicity); (c) specific components thought to have nutritional or toxic properties; (d) the stability of the inserted gene; (e) nutritional effects associated with genetic modification; and (f) any unintended effects which could result from the gene insertion” (WHO 2002: 2). A majority of the scientists claim that GM crops have the potential to rid starvation from the various developing and under developed nations, as transgenic crops could produce food in greater quantities that would be more nutritious. Yield would be higher as GM crops are pest and drought resistant, while containing greater nutrients, such as vitamins and proteins. Despite all the aforementioned advantages, however the anti-GM lobby are sceptical about the actual safety of GM crops. They claim that there may be issues concerning the presence of allergenic substances owing to the addition of new genes. Furthermore, it has been claimed that genetic engineering makes use of genes that are antibiotic-resistance in nature (selectable markers) which in turn would create bacterial strains that would be antibiotic-resistant to the currently used antibiotics leading to a public health issues. The GM crops also might have other toxic substances, as for example heavy metals, that could prove to be dangerous for human health. Another area of concern is that GM crops may actually be less nutritious; than the researchers claim, and might contain less phytoestrogens that safeguard against cancer and heart disease. While a detailed study of the literature suggests that the available GM crops used for human consumption are safe and cannot be associated with any kind of health issues, however, more research is required to ensure that GM crops produce food that is safe for human consumption. Although WHO has confirmed that all GM crops currently found in the global market are rightly assessed at a national level for food and environment related risks, a review of the literature review clearly shows the lack of scienti?c literature that gives correct information regarding such assessments (Domingo 2000). Especially there has been a serious dearth of scientific studies (toxicological) on the negative impact of GM crops on consumer health. Given below are some of the toxicological studies conducted on two popular GM crops, soybeans and maize. Soybeans Research by Padgette et al. (1996) on detailed compositional studies revealed that glyphosate-tolerant soybeans or GTS seeds were significantly similar to the parental soybean types that are available commercially. In another study, the safety of result of the modified gene, 5-enolpyruvylshikimate-3-phosphate synthase received via Agrobacterium sp. Strain CP4 that is highly resistant to blockage glyphosate, was experimented on mice (Harrison et al. 1996). Researches revealed that no negative impact in animals that were dosed with CP4 EPSPS protein (up to 572 mg/kg of the body weight). This dosage is significantly higher than the safety margin as regards the maximum potential for human consumption of CP4 EPSPS protein (taking into consideration that the protein is asserted through multiple crops. However, the researches revealed that CP4 EPSPS protein was safe for mammals when they faced exposure at acute levels. Although the compositional research showed the GM soybean crops similar to commercial soybean types, experiments were conducted into animal feeding patterns in order to give evidence for the new GM soybean. Feeding trials were experimented on broiler chickens, dairy cows and rats as part of a program related to safety assessment. Two GM varieties and a parental variety were used for feeding all animals and their gain-to-feed performance and growth were noted. No significant differences were observed between the GM and parental lines and there were no differences in the presence of essential nutrients (Hammond et al. 1996). However, while the protein administered was safe, the experimental period was too short [ranging from brief 4 weeks to 10 weeks period] to derive any strong evidences. Information about the composition of GM soybeans is necessary as this crop is popularly used for making soymilk and other health food products. In terms of composition, Cromwell et al. (2002) showed that GM soybeans were essentially similar in nutritional value and composition to the normal soybean meal given to pigs. However, other researchers feel that more research is necessary to arrive at a sound scientific conclusion in this regard (Cantani 2006). Maize The first plantings at a commercial level of GM maize hybrids, also known as Bt corn, took place in 1996. These hybrids were derived from a genetic modi?cation labeled as Event 176, where the genetic code allows the plants to create protein, Cry1Ab (insecticidal on characters), which is similar to that produced by a common soil bacterium Bacillus thuringiensis. To study whether the Event 176-derived GM corn had any negative impact on broiler chickens, Brake and Vlachos (1998) conducted a 38-day research on both male and female chicken. There were no signi?cant differences in body weight and survival rates between chickens that were fed GM corn and those that were fed parental corn, thus proving that transgenic corn produced no negative impact. Research with Bt maize on pig nutrition was performed by Reuter et al. (2002). In their studies, composition of GM (Bt) and parental varieties of maize grain and their nutritional values and digestibility values were studied (Reuter et al. 2002). From this research, it was derived that the GM maize used in this study was equivalent to the parental maize line. In another study by the same researchers, records were kept for 91 days of growing period where it was observed that pigs from both groups showed similar performances as regards weight gain, thus con?rming no substantial differences between GM maize or parental maize diets. In one of the few research conducted by a biotechnology firm involved in GM foods was Hammond et al. (2004). These authors performed a 13-week feeding experiment on rats that were fed with GM maize grains from Monsanto, (tolerant to glyphosate herbicide). The observations were then compared with these of rats, which were fed parental non-transgenic crops. According to the researchers, the study con?rmed that GM maize is as safe and nutritious as the current hybrids available commercially, however here the major drawback is the short period of 13 weeks, during which the GM corn was administered. Name of GM crops Animals used for research Result of the research Name of researchers GM Soybeans (Glyphosate-tolerant) rats, chickens, cows No signi?cant effects Hammond et al. (1996) GM Soybeans (Glyphosate-tolerant) Dairy cows No signi?cant effects Padgette et al. (1996) GM Soybeans (Glyphosate-resistant) mice No negative impact Harrison et al. (1996) Maize (Event 176-derived) Broiler chickens transgenic corn produced no negative impact Brake and Vlachos (1998) Bt Maize pigs no substantial differences Reuter et al. (2002) GM maize grains from Monsanto (tolerant to glyphosate herbicide rats No negative impact Hammond et al. (2004). Table 1: A brief review of some of the case studies on dietary administration of transgenic soybean and maize to different animals. The cases studies uniformly point to the single result that transgenic or GM crops have no adverse effects on animals they were used on, hence refuting the claims of the anti-GM crop lobbyists that transgenic crops are potentially harmful for human consumption. Conclusion With the GM crops being a relatively new subject there is a serious lack of data on both the benefits and adverse effects. In a majority of the cases, the opinions are based on assumptions and further research is necessary to arrive at any scientific conclusion. The current research conducted on food and environmental safety of GM crops is not sufficient, and for a safe use of GM food, mere analysis of chemical composition of the GM and conventional crops are not suf?cient. In vivo studies, along with relative studies of the nutritional similarities between GM and conventional crops must be undertaken. These are necessary to not only study the potential negative transgenic effects, but also have a basis on the consumer’s right to information on food and environmental safety. While conducting a literature review on potential negative effects on consumer health from genetically modi?ed crops, Bakshi (2003) claimed that from an overall view, it is generally safe to consume GM food as there no evidences of any serious health problems. However, the author has claimed that genetic engineering being a relatively new technology is still in its nascent stages. Thus, scientists lack a complete understanding of genetics, nutritional value and physiology of transgenic crops. This could create a failure to predict the negative effects of GM crops, including the risks that are yet to be identi?ed. Some experts claim that GM crops may have allergenic substances owing to the presence of new genes. There might also be the presence of other toxic metals (heavy metals) in GM crops, while they may fail to be ‘substantially equivalent,’ when compared to the parental crops. While conducting the literature review it was noted that there was a serious lack of experimental data on toxicity studies and most of the researches conducted were short-term experiments, which were mainly nutritional studies, with very little toxicological data. 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