The World Health Organization defines genetically modified foods (GMO) as “organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally”. It involves technology often referred to as gene technology, modern biotechnology or genetic engineering. The process allows for selective transfer of genes from one organism to another. The transfer of genes can be done between organisms of the same species or of different species. Genetic engineering has been practiced for many years. We often hear of cases where a specific gene is selected from an animal or plant and introduced into a different organism to express the desired traits. For example, in the production of sweet corn, gene recombinant viruses, and herbicide tolerant soybeans. This technology has majorly been applied in the agricultural field to increase the production of food and pharmaceutical substances of value.
A lot of resources and time are channeled to research and production of genetically modified foods because of their perceived benefits. In agriculture, the benefits of this technology include increased yields of crops, reduced costs of food production, enhanced food quality and composition of nutrients and increased resistance of crops to pests. In the medical field, the technology is used to produce vaccines through the process of gene recombination. An example of a vaccine produced by this process is the hepatitis B virus vaccine.
The major reason behind the application of genetic technology on the production of plants is to enhance crop protection. Research is, therefore, done to produce plants that are more resistant to diseases caused by viruses and insects, and tolerant to herbicides. To increase resistance to insects, the gene that produces the toxin for the bacterium Bacillus thuringiensis is introduced into the desired plant. The toxin is an insecticide that when produced by the plant, kills disease causing insects. This method has been shown to reduce the amount of insecticides used on plants in places where pests are endemic. The resistance to a viral disease is increased by introducing a gene from the virus. To produce plants resistant to herbicides, a gene is removed from a bacterium expressing some resistance to herbicides. This technic has, particularly, been beneficial in farms with weed problems. It reduces the amount of herbicides used to control the weeds, hence reduced production cost.
Genetic technology is also used in animal production. Genetically engineered animals have shown more resistance to diseases. It is used to produce bigger animals with a faster rate of maturity than the normal animals. For example, genetically engineered salmon are bigger and mature faster. Cattle have been genetically modified to express increased resistance to mad cow disease..
The main drawbacks linked to genetically modified organisms are allergenicity, outcrossing and gene transfer. Allergenicity is the ability to induce an allergic reaction. It may result from the transfer of a gene from an allergenic food. To prevent allergenicity, the Food and Agricultural Organization came up with a set of protocols, which ensures GMOs are tested for allergens. Gene transfer can be of concern when a gene transferred from the GMO to the cells of the body causes adverse health effects. Gene transfer may also affect human health when a gene is transferred to a pathogenic bacteria present in the gastrointestinal tract. The result is that the bacteria can become resistant to antibiotics used against it. Outcrossing describes the process by which genes from genetically modified plants are transferred to other plants in the wild, or to crops grown together with GM crops. For, instance a gene may be transferred to a weed crop making it more resistant to herbicides. This effect pauses a big threat to food security.
In 2007, the International Food Information Council (IFIC) conducted a survey to assess the public’s opinion to genetically modified organisms. Of the 1,000 American adult respondents, 33% were of the opinion that GMOs were of benefit to them and their families, 23% had no idea that GMOs were in the food market, and 5% said they would make changes in their choices of food due to the perceived adverse effects of the GMOs. The acceptance of modern biotechnology by the public is varied depending on the level of education of the person or their personal beliefs. While most people readily welcome the idea of genetically modified plants, few entertain the application of the technique on animals. Still there are people who refuse to accept GM foods even after their safety have been thoroughly tested. Their reasons may be personal or religious. Religious debates against GMOs question the ethics behind the technology. The argument raised is that we assume the “role of God” by modifying His creation to satisfy our desires. In addition, religious antagonists are against the idea that gene transfer may involve a plant or animal that the religious group abstains from. Other people are of the opinion that it is morally wrong to interfere with nature, and that transfer of genes between organisms is not right. Due to the variant opinion on GMOs, it is important to clearly label GM foods from non-GM foods in order to give the public an easy time to choose. The assessment of the constituents of GMOs is also vital to ensure they are universally accepted.
Agricultural biotechnology has resulted into the production of commercially approved genetically modified organisms. One example is the production of herbicide tolerant soybean. Herbicides are used to control weeds in farms. However, most herbicides cannot differentiate between weeds and crops and may end up killing both. The farmer, therefore, has to use only selective herbicides to fight weeds. The use of herbicide resistant crop allows the farmer to apply non-selective herbicides to his farm. This reduces the amount of time and cost of spraying the farm. GM soybean is made glyphosate herbicide (Roundup) tolerant by introducing a gene that codes for a glyphosate tolerant enzyme, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). The gene is removed from the bacterium Agrobacterium tumefaciens, strain CP4. The soybean produce the plant form of the enzyme, which neutralizes glyphosate herbicide when applied on it.
Insect resistant corn to reduce the losses incurred when insects attack corn in silos, and increase corn quality. It is estimated that each year, insects destroy up to 25% of food crops globally. One major organism identified with the ability to destroy up to 20% of a maize cob is the Ostrinia nubilalis’ larvae. Insect resistant corn is produced by the use of a gene from the bacterium Bacillus thuringiensis. The bacteria produces a toxin that kills herbivorous insects. The inactive Bt toxin is activated to a delta endotoxin when consumed by an insect. It kills the insect by damaging its gut. This technique is specifically used on the European corn borer. The gene from the bacterium is introduced in the corn which in turn produces the protein toxin.
Gene technology has also been used to develop crops with enhanced nutritional contents and of high quality. This is normally aimed at meeting the needs of the consumer. Crops with modified fatty acid content have been produced. For instance, canola can be modified to have high levels of the fatty acid, laurate. The process involves the introduction of a gene from Umbellalaria californica, California bay tree. Golden rice, which is enriched with pro vitamin A is a product of gene technology. Three genes that code for beta-carotene are present in the rice endosperm and prevent the removal of the vitamin (husks) when milling is done. Naturally, rice contains very little amounts of beta-carotene. This technique has come in handy in areas where vitamin A deficiency is widespread.
Infectious agents such as bacteria, fungi, and viruses can cause disease in plants. Fungi causes diseases like blight, and mildew. Fungal resistant crops can be produced by introducing genes, that code for enzymes such as gucanase, from bacteria. Viruses, for example, Beet necrotic yellow vein virus, affects sugar beets causing them to have smaller roots, hence reduced yields. Virus resistant genetically modified plants can be produced by introducing a viral gene, which encodes for coat protein, into the plant. The plant in turn produces this protein and when the virus infects the plant, the protein prevents it from replicating.
References
foodinsight.org. (2009, October 29). Food Biotechnology: A Study of U.S. Consumer Attitudinal Trends, 2007 REPORT. Retrieved from Food Insight: http://www.foodinsight.org/Resources/Detail.aspx?topic=Food_Biotechnology_A_Study_of_U_S_Consumer_Attitudinal_Trends_2007_REPORT
Phillips, T. (2008). Genetically Modified Organisms (GMOs): Transgenic Crop and Recombinant DNA Technology. Retrieved from Scitable by nature education: http://www.nature.com/scitable/topicpage/genetically-modified-organisms-gmos-transgenic-crops-and-732
who.int. (2013). 20 questions on genetically modified foods. Retrieved from World Health Organization: http://www.who.int/foodsafety/publications/biotech/20questions/en/
