Genetically modified crops are plants used for agricultural purposes in which the DNA of a particular trait in a plant is modified using genetic engineering techniques. The aim of this is to introduce a particular trait to a crop, which would not normally occur naturally in the species. Examples of genetically modified crops include resistance against pests, environmental conditions and diseases and increase yield production of the particular crop to accommodate for an ever-growing world population. (ISAAA Annual report, 2013).
In the early 1900’s genetically modified crops were referred to as biotech crop and were the high topic of the time as they could deliver improved products and make an impact at a very high level. There was even more skepticism when it came to talks about genetically modified crops being used in developing countries to help with food poverty and the growth of crops in areas of unfavorable conditions.Farmers in the modern era have widely used GM technology to increase their yield production and protect their plants from the number of changes within the world such as climate change and the resistance against pests and diseases.
In the past 20 years genetically modified crops have increase by a factor of 100, from 4.2 million to 432 million acres, which makes 10% of the world arable land inhabited by genetically modified crops. (Economic and Social Development Department, 2002)
The use of genetically modified crops are becoming ever more popular in developing countries, with about 18 million farmers growing 54% of the worldwide genetically modified crops by 2013 and have shown that this increase in genetically modified crops has reduced the amount of pesticides used by almost 37%. This use of genetically modified crops within developing countries means that the crops are able to grow in extreme conditions such as high temperatures, low temperatures, high salinity and drought and in which the crops would not be able to grow if not engineered. The growth of GM crops helps reduce starvation and food poverty and yield and profit gains are often higher in developing countries than in developed countries.
The potential impact of genetically modified crops on biodiversity has been a highlighted topic of interest for many organisations including the convention of biological diversity when it comes to growing and engineering these modified crop. Agricultural biodiversity has been defined ‘at levels from genes to ecosystems that are involved or impacted by agricultural production’. (Lombardo, 2015)
Advantages of genetically modifying crops
With an ever growing world population, and the increase of 3rd world hunger, the need for genetically modified crops is increasingly becoming more popular.
There are many advantages to genetically modifying crops, these advantages include creating plants which are better resistant to weeds, pest and other diseases to prevent the reduction in yield further more reducing profits for the farmers. This method has been used widely in corn species and is the most important and widely grown grain in the United States of America. (Fernandez-Cornejo and Wechsler, 2015). However corn cannot reproduce without the need for human intervention as corn is very susceptible to pests and diseases and also requires a lot of nutrients in order to grow to a sufficient size to accommodate a human’s appetite. The need to genetically modify corn would result in bigger yield to create more efficient land use and less need to use pesticides and herbicides for efficient growth, the food produced will be better texture, flavor and nutritional value, it can be modified so that it has a longer shelf life making it easier for produce to be shipped to other countries without it going off by the time it reaches its destination. (James, 2011)
Genetically modified crops also have a positive environmental impact, as soil salinity has become a major problem in today’s agricultural lifestyle, especially in areas such as San Joaquin Valley. This had made the natural crops less able to grow and in some cases have caused them to die off or not grow at all. The reason why the crops cannot grow in this area is due to high levels of salt, therefore to solve this problem; there is a possibility of using a salt tolerant gene, which would make the crops less susceptible to saline conditions. One method in which this has been used is in tobacco plants, tobacco plants are very susceptible to saline conditions therefore placing a gene from the grey mangrove (Avicenna marina) into the tobacco plants genome would make it able to tolerate salt stress as well as showing a tolerance to ionic stress. (Conner, Glare, and Nap, 2003)
Not all crops need to be genetically modified for food purposes but one big advancement in genetically modifying crops is the ability to produce edible vaccinations, the genetic engineering of plants has the potential to provide edible plants vaccines that can be used to vaccinate against a wide range of infectious diseases ranging from the flu to potentially AIDS. An example of where this has been used is in a transgenic potato plant in which the crop produces a pharmaceutical immunization against diarrhea. (Genetically Modified Foods, no date)
Disadvantages of genetically modifying crops
Among all the benefits of genetically modifying crops there are also a lot of disadvantages to this process.
Genetically modifying crops can cross contaminate with the natural plants, this can develop into the ‘super-weeds’ that have the same resistant properties as the crops have meaning that they will be more difficult to remove or destroy.
The rise of allergies in children has also risen since the introduction of genetically modified crops but there has not yet been an exact link to the crops being the reason but this could be due to the lack of research in this area.
Crops have also been genetically modified to have antibiotic properties put into them in order to withstand a number of bacterial infections and diseases but over use and exaggeration of these antibiotic can make them less effective. They can also be bio-accumulate within the human body when digested making many antibiotics less effective within humans causing the increase of diseases and resistant bacterial infections.
GM crop have had little testing and research done on them and the possibility of long term effects have not been discovered yet meaning that a lot of people feel anxious about the use of these scientifically corrected foods. (Mirabzade Ardekani, 2014)
GM crop engineering techniques
Adding or removing genes from a genome using genetic engineering techniques is the main process of creating genetically engineered crops. There are many methods in which crops can be modified, one method is a process known as biolistic; this is the use of gene guns, which ‘shoot’ high-radiated target genes into a plant cell. It is the most common method when it comes to genome transformation. The DNA is bound to tiny particles of gold and is shot into the plant cell under high pressure. This DNA separates from the metal and penetrates the cell wall and the membrane and integrates into the plants DNA genome within the nucleus. This method is commonly used in monocots like maize and wheat in which the method of using Agrobacterium has been less successful. The use of a gene gun does have a disadvantage; that is that the high radiation can cause serious damage to the plants tissues causing defects in the plant.
Another method of genetic engineering is the use of a bacterium known as Agrobacterium tumefaciens. This bacterium is a natural plant parasite and there natural process of transferring genes is a common method in this process.
For the bacteria to have a suitable environment to live in, they insert genes into plant hosts, resulting in a change in the genome and a proliferation of modified plant tissues near the top of the soil.
The genetic information is placed within a plasmid (circular DNA fragment), when agrobacterium infects a plant in the process it transfers the T-DNA of the plasmid to a random site but in the process of genetic engineering the T-DNA is removed and replaced with a foreign gene. The bacterium becomes a vector, which allows the transport of foreign genes across the cell wall and membrane enabling it to change it genome and change the properties, characteristics and function of the plant but introducing new genes to a sequence requires a promoter of a specific sequence where the gene is to expressed therefore finding this promoter can often be a difficult task. This method is more commonly used in dicotyledonous plants such as potatoes, tobacco and tomatoes and is less useful in monocots such as maize and wheat. (Shrawat and Lörz, 2006)
Another method but isn’t as commonly used as the above is electroporation. This is used when a plant does not contain a cell wall and the new DNA is inserted through tiny pores by electric pulses, one other way is by injecting the new DNA directly into the plants genome, this is called microinjection but these methods have shown to have more errors when trying to produce genetic modified crops therefore the use of Agrobacterium and the gene gun are more commonly used.
Types of genetic modification
There are three types of genetic modification methods these are;
Transgenic – these are plants that have had genes inserted in the DNA of the plants genome that have derived from another species. This species can be either from the same kingdom or between different kingdoms (animalia to plantae). The problem with using DNA from different kingdoms is that it has to be modified to efficiently fit the needs and requirements of the host cell it is being inserted into. Transgenic plants are often used to express proteins such as cry toxins from the gram positive stain soil dwelling bacteria B. thuringiensis, antibodies, herbicide resistant genes and antigens for vaccinations. (McKie, 2016)
Cisgenic – these are plants that are produced using gene, which are found within the same species or closely related, this method is commonly used for plant breeding for plants that are difficult to crossbreed such as potatoes. (MacKenzie, 2008)
Subgenic – these are wheat plant that have been genetically modified to become resistance to powdery mildew. The strain lacks the genes that produce the protein that repress defenses against mildew and therefore causes the plant to die, the strain is also beneficial to the environment as it prevents the over use of fungicides to control the disease. (Wang et al., 2014)