This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.
Until today, genetic engineering has caught many attentions of people from all over the world especially those in agriculture field through genetic modified (GM). Genetic modified definitely bring great fortune to people in agriculture world. Through genetic engineering crops has been modified into insect resistant crops, disease resistant crops and also drought tolerant crops. However, this advancement leads people worries due the GM. People are concern whether or not the GM could bring any effects to surrounding.
Will insect develop resistance to bacteria toxin produced by transgenic insect resistant (Bt) crops? Will planting herbicide tolerant GM crops result in development of plant that resistance to herbicide? Will insect resistance crop lead to the death of non-target insect thus decreasing diversity of insect? Will the crop affect the soil organism? Also will GM crop lead to the extinction of the plant when its cross pollinate and will GM crop affect the plant biodiversity? Lastly the biggest concern are the GM crops can effect human health and it is environmentally safety?
Genetic modified being introduced to the world to help people minimize the use of herbicide thus cause less pollution.
Environmental problems was related to the term genetically modified (GM) plant that can be classified to three categories. Firstly, the GM plant in itself can be harmful to environment or agriculture. Secondly, cultivation of the GM plant can lead to environmentally unacceptable agricultural practices. Thirdly, the spread of the genetic material of the GM plant to other organisms can be harmful. To control this problem, plant biotechnology was focus on herbicide resistant plant because herbicide resistance is the most important genetic modification in crop plants.
Herbicide resistance is about an ability of a weed or crop biotype was inherited to survive a herbicide application to which the original population was susceptible. There have weed characteristics that favour resistance. Weeds have a diverse genetic background that give them the ability to adapt to many different environmental. For example, the repeated mowing of a lawn selects for low growing plants that avoids or are not affected by repeated cutting. As an herbicide resistant biotype become more predominant in the weed population that two factors increase in importance, there are weed reproductive capability and weed seed dispersal mechanisms. The greater the reproductive success of the resistant biotype, the greater its potential to spread and become a dominant part of the population. Due to the extended viability of most weed seeds, once it was established, a herbicide resistance biotype will be difficult to eliminate from the population, even if extensive corrective weed control measures are used. When to prevent the resistant biotype from developing on the land and prohibit the establishment of resistant weed biotypes spreading from adjacent lands, a farm manager must always use good herbicide resistant management strategies.
For minor use crops, it may be economical to breed herbicide resistance into a crop than to develop new selective herbicides for current crop varieties. While for major use crops such as corn, soybeans and wheat, herbicide resistant crop may be useful but difficult to control weed or environmental conditions dictate the use of specific herbicides to which the crop is normally susceptible. However, the use of herbicide resistant crop could enhance the potential for selecting for herbicide resistant weed unless careful management practices are followed.
Herbicide resistant crop varieties or hybrid need to be carefully evaluated for other performance characteristics and these characteristics should be compared to all other suitable hybrids or varieties in the marketplace, whether they have herbicide resistance or not. This will ensure that crop producers are getting the best overall agronomic value for their money. It will also be very important that accurate records be kept of the exact planting location of the herbicide resistant crops to avoid herbicide misapplication.
According to Nelson (2001) by US Environmental Protection Agency, the statistic on 1999 stated that 4.5 billion pounds of pesticides are applied to US field every year. The worldwide damage caused by pesticides has been estimated at $100 billion per years stated Myers (1998). This shows that harmful agriculture has been brought on largely unchecked industry in farming. Therefore, these industries have created unsustainable methods to solve these matters. They invented genetically engineered crops to solve these problems. From the invented genetically engineered crops, they have caused another problem from what they created. This causes the unpredictable effects of gene mixing such as Arabidopsis thaliana, the mustard plant family. Arabidopsis thaliana is a self-pollinating species with very low rates of cross pollination. The experiment was designed and the results showed that A. thaliana demonstrated very higher rates than a traditional breeding. The dramatic variation has great implication for biotechnology and controversy releasing transgenic crops to the environment.
The results of releasing many mixing of genes from many different sources can cause ecological risks. Bt crops is a genetically modified crops that have been engineered the traits to make the corn resistance to herbicide and insect pest. Bt corn were develop to deal with the crop damage from European corn borer, Ostrinia Nubilalis. The traits were achieved by incorporation of gene that codes for Bacillus thuringenis (Bt) which is toxic poisonous to the insect pest. According to Saxena et al. (1999), Bt corn released Bt toxin into the rhizophere soil from its roots. They concluded that many non-target insect, organisms and microbial communities could be affected by this toxin. When the corn planted in a large scale, the problems that could have is the corn may affected by fungus and European corn borer (ECB), an insect pest that eats and destroys corn stems. So, when these problems happens the yield of the corn will become lower than expected. It will affect the market of corn. To overcome this problem, corn is introduced to be transgenic. This transgenic crop receives a gene from an insect pathogen, Bacillus thuringiensis (Bt), which encodes a protein that toxic to the ECB, an insect that eats and destroys corn stems. Bt corn has proven that it is effective in reducing crop damage due to ECB. The other benefit is it reducing the toxin that produced by fungus. Bt has ability that It can reducing crop damage effectively. In public opposition, they are worried of human health and environmental risks that are associated with the production and consumption of Bt corn. At the earlier, the Bt grown in large quantities and sprayed on corn crops to prevent the ECB damage. There is no toxic effect of Bt on humans have been detected in its seventy years of use, and now, it is now considered and acceptable pest control measure for organic food industry. The success of spray is actually has problem where when it is sprayed on crop, the bacteria cannot survive for very long time on plant's space. The other problem is it is not effective sprayed on outside because the ECB is located in the corn crops. So, scientist promote the gene of Bt into the plant.
To solve the problems that is facing by the farmers, scientist come out with the idea that is by using herbicide. A few types of factors that come out that is competition of the farming with the grass-weed, the disease that being carried by the insect might be spread to the farming and the shape of the farming and the grass-weed might confused the farmer.
Herbicide is the chemical that kill or inhibit the normal growth of the plant. It's often used and most effectively with the good cultural practice in turf management program. The combination choices are depends on the agronomic, ecological and economic factor. If the herbicides are too expensive the farmer might be in big problems and might not use the recommended herbicide.
Herbicides have two types that are selective and non-selective. Selective herbicide kills or stunted the turf grass with little or no harm towards the turf grass. In other hand, kill only the unwanted grass leaving the desired. While the non-selective will kill or damage all plants when applied at adequate rates. Herbicide will be acts according to the time and methods applied, chemical formulation, environmental conditions, stages of the turf grass and weed growth and particular dosage of the chemical in the herbicide. Herbicide killing plants through contact action or systematic action, but the contact action is more effective compared with the systematic action. Contact actions are effective against the annual weed and kill only the parts that is deposited chemical substances.
First company which develops is in 1940s by the paint company Sherwin-Williams. This company was use 2, 4-dichloropheoxyacetic acid (2, 4-D). After being commercialized by this company, 2, 4-D was use widely until today due to the low cost to buy it.
Herbicides have the negative effect toward the grass crop if being use in high doses. Some of the effects if in acute toxicity from high exposure level the possible carcinogenicity while in long term will contribute the Parkinson's disease. All this effects are cause by the intentional or unintentional direct consumption, improper application (direct contact) and many more. But most of the herbicide was decompose rapidly in by microbial decomposition (hydrolysis, photolysis). This is due to the way to apply this herbicide by airplane or water-based spray using ground equipment that might be go to another places by wind.
After being analyze by the government the herbicide used are not as the recommended, so special communities are form to monitor the farmer activity. Another action that being taken by the government is by labeled the safe product for the user to identify. Example of plant that use herbicide is barley's farm.
Food Safety Considerations:
Usage of Selectable Marker gene:
Genetic engineering has been applied on agricultural crop to produce crops with favourable traits such as Insecticide resistance crop and also Disease resistance plant (Brooker, 2011). However, the techniques used in transferring of a new gene into a plant are rather inefficient. Very few of the cells actually take up the gene of interest. Hence, in order to differentiate and isolate the transformed plant crop cells for further propagation, selectable markers are needed.
Selectable marker most widely used currently is the antibiotic resistance marker gene. (Adrian et al, 2008).
These markers gene are integrated into the plasmid of agrobacteria along with the desired gene onto the T-region. Next, the crop tissues are grown together with the agrobacteria in a medium. Through infection on wound of the cut plant tissue, the desired gene and selectable marker will move into the plant tissue from the agrobacteria (Adrian et al, 2008).
The tissues are then incubated in growth medium consisting antibiotics. Crop tissues that do not contain the antibiotic resistance gene (the selectable marker) will be destroyed. Since only cells that contain the antibiotic resistance gene can survive, scientists can be sure those surviving plant cells also contain the desired gene. These crop tissues are then allowed to grow, producing crops with desired traits. The new crops are then propagated to produce more crops with the desired traits (Chawla H S, 2009).
Though the new crops produced show desired traits such as disease resistance or insecticide resistant, they also contain the selectable marker. Since the selectable markers used are mostly antibiotic resistance gene, the consumption safety of these transgenic crops has been questioned (FDA, 1998).
When scaled-up the usage, the consumers will face a higher level exposure towards the antibiotic resistance gene. It has been thought that accumulation of these genes, will eventually be transferred into a consumer's body. The result is that a certain antibiotic for treatment may no longer be effective in that particular person's body, thus leading to much serious diseases. This can be fatal since certain antibiotics are unique drug available to treat certain diseases. An example would be the staphylococcal infections which can only be treated with Vancomycin. Staphylococcal toxin are major cause of food poisoning and much severe staphylococcal infections such as wound infections and pneumonia may leads to death (FDA, 1998).
Apart from that, it has also into consideration whether the antibiotic resistance gene will be integrated into bacteria residing in human and also plants. This may cause some pathogenic bacteria to be resistance toward the antibiotic thus rendering some antibiotics to be ineffective towards the bacteria causing disease. Also, a high scale up usage of the antibiotic gene may result in selective pressure, producing a large population of highly antibiotic resistance pathogenic bacteria (Mahesh S, 2009).
In already to ensure that the transgenic crops are safe to be consumed, protocols are created on controlling and managing the production. Food and Drug Administration, United States stated that developers should evaluate the use of antibiotic resistance marker genes in crops on a case-by-case basis taking into account information on 1) whether the antibiotic is an important medication, 2) whether it is frequently used, 3) whether it is orally administered, 4) whether it is unique, 5) whether there would be selective pressure for transformation to take place, and 6) the level of resistance to the antibiotic present in bacterial populations(Adrian et al, 2008).
Apart from that several solutions had been taken to ensure that the transgenic plants are safe to be consumed.
Firstly, removal of the selectable marker gene from the tissue before growing on the field. This can be done by either co-transformation of two transgenes and excising selection marker by sexual crosses or the direct excision of the selectable marker gene out of the transgene in the plant genome after the selection procedure (Brooker, 2011).
Co-transformation methods are based on the principle that a proportion of transformed plants carrying the selectable gene will also have integrated the required trait transgene at a second unlinked insertion site. The selectable marker is then removed using sexual crossing. However, only a proportion of plant carrying the selectable marker will also carry the desired trait at an unlinked site and co-transformation methods cannot be used for vegetatively propagated plants (Adrian et al, 2008).
Apart from that, direct excision after selection procedure have also been used. The "cre/lox" marker gene removal system is a method which includes a number of techniques use genetic tools that act as "molecular scissors" that can actually cut certain genes out of the genome. The gene encoding these scissors is introduced along with the marker gene and the gene of interest. Once transformed cells have been selected, scientists activate the gene encoding the scissors by an external stimulus. The scissors then cut out the marker gene and the gene for the scissors themselves, making the resulting plant completely free of marker genes (Adrian et al, 2008).
Secondly, using resistance gene in which the antibiotic in concern have no medical value. Such antibiotic includes t. For example: The most widely used antibiotic resistance marker, npt II, confers resistance to the antibiotics kanamycin and neomycin. These antibiotics are no longer used to any significant extent in medical applications because they have severe side effects and many bacteria are already resistant to them(Mahesh S, 2009).
Lastly, by using alternatives other than antibiotic resistance gene. This includes the usage of Herbicide resistance genes. After treatment with an herbicide, only the plants having the herbicide resistance gene and desired gene survive. Another alternative is marker genes that enable the plant cell to use particular substances as food source: The extracted plant tissues are fed with only this type of substances, hence only the plants that have successfully incorporated the new genes will be able to grow. An example of this approach is the PMI gene which enables the plant cell to use mannose, a type of sugar, as a source of energy (Mahesh S, 2009). The new 3272 maize are developed using this technique. There also genes that enables the plant tissues to produce protein which bind to heavy metal. Apart from these markers that can't be seen, visible markers are also being used. These include gene for the green fluorescent protein (GFP) which makes genetically modified plant cells appear green when exposed to UV light, making the transgenic tissues clearly visible and easily recognized. The only major disadvantage to this technique is that modified and unmodified cells must later be visually separated, which can be very tedious compare do other alternatives (Adrian et al, 2008).
Jennifer A Thomson 2006. GM Crops The Impact and The Potential. Australia. CSIRO Publishing. 158 pages
- Robert J. Brooker (2011). Genectics Analysis and Principles 3rd edition.
The United State : McGraw Hill.
- Adrian Slater, Nigel Scott, and Mark Fowler (2008).
Plant Biotechnology the Genetic Manipulation of Plants
Oxford University Press.
- Chawla H S (2009). Introduction to Plant Biotechnology 3rd Edition.
The United State: Science Publishers,U.S.
- Mahesh S (2009). Plant Molecular Biotechnology. New Age Science.
- Food and Drug Administration (1998). Guidance for Industry
Use of Antibiotic Resistance Marker Genes in Transgenic Plants
Draft Guidance. The United State : Department of Health and Human Services.
Examples of Transgenic Crop