Genetically Modified or GM Crops are that type of plants whose DNA has been modified through genetic engineering for embedding a new trait to the plant which does not occur naturally in the species.
Crops produced from or using genetically modified organisms are often referred to as genetically modified crops.
History of GM crops
The genesis of DNA modification technology can be traced back to 1944. Several hallmark papers paved the way to the modern science of molecular biology. In 1954, Watson and Crick discovered the double helix structure of DNA.
Then established a concept that DNA transcribed to mRNA and this translated to protein in central dogma. Nobel Laureate Marshal Nirenberg and others had deciphered the genetic code by 1963.
In 1973, Cohen et al. developed DNA recombination technology, in which it was described that DNA molecules can be transferred among different species.
The history really begins with Charles Darwin’s notions of species variation and selection. Antibiotic resistant tobacco and petunias (first genetically modified plants) were produced by three independent research groups in 1983. Scientists in China first commercialized genetically modified tobacco in early 1990s.
In 1994 the US market saw the first genetically modified species of tomato. Since then, several transgenic crops have received FDA approvals, including “Canola” with modified oil composition, cotton and soybeans resistant to herbicides, etc. Genetically modified foods that are available in the market include potatoes, eggplants, strawberries, carrots, and many more are in pipeline
Do we need genetically modified crops?
Before starting discussing the merits and demerits of genetically modified foods, it is important to set forth why there is such great effort to develop them. There are three major challenges we are facing that motivate our resort to the new technology for help.
- Expansion of population
- Decrease in arable land
- Bottleneck of conventional and modern breeding
Generation of genetically modified crops
In order to generate GM foods, researchers need to introduce the genes coding for certain traits into a plant cell. Then regenerate a plant through tissue culture. When and where the transferred gene is expressed is usually inherent in the scheme. There are three ways to modify genes in the cells.
1. Directly transfer DNA
The most widely used technique for delivering exogenous DNA is microparticle bombardment. Sanford developed the technique in 1980. Naked, engineered DNA is coated on gold or tungsten microparticles. Which, in turn, are delivered at high velocity into targeted tissues, such as embryonic tissues from the seed or meristems.
There are other ways to deliver DNA into plant cells. Including electroporation in which letting the negatively charged DNA move down an electric potential gradient into protoplasts, microinjection, chloroplast transformation, silicon-carbide slivers, mesoporous silica nanoparticles, etc.
However, particle bombardment remains more effective at transferring large DNA fragments even whole chromosomes simultaneously.
2. Indirectly using bacterial vehicle
The use of Agrobacterium tumefaciens opened a new era for inserting exogenous genes into plant cells. The soil bacterium A. tumefaciens infects plants, forming a gall at the crown. The bacteria alter the genome of the plant, not only causing proliferation of the plant cells. But also enabling the plant to produce modified amino acids as a specialized food source for themselves.
The bacteria possess a tumor-inducing plasmid (Ti-plasmid), which enable them to accomplish gene-insertion; researchers hijack the plasmid by inserting “designer gene’s” into the T-DNA (transfer DNA) section of the Ti-plasmid.
3. Direct editing of genomic DNA
CRISPR-Cas9 system was developed in 2012. It constitutes a revolutionary genome editing tool, and provides another method to alter genes in various type of cells.
This technique increases the efficiency of genetic engineering and make it much easier to work with plants. Cas9 is a DNA endonuclease originally found in bacteria. Where it protects the host bacteria from invading DNA molecules.
The endonuclease is guided to the invading DNA by a special guide RNA. Whose sequence is complementary to the invading sequence to be removed. Thus guided by the offensive, Cas9 utilizes its two active sites to cleave both strands of the double-stranded DNA.
The newly formed DNA double-stranded breaks are then repaired by two different mechanisms inside cells. The non-homologous end joining mechanism can cause a small deletion or random DNA insertion, leading to a truncated gene or knockout.
Are genetically modified crops safe to eat?
GM crops are tightly regulated by several government bodies. The European Food Safety Authority and each individual member state have detailed the requirements for a full risk assessment of genetically modified plants and derived food and feed.
Therefore in the USA, the Food and Drug Agency, the Environmental Protection Agency and the US Department of Agriculture are all involved in the regulatory process for genetically modified crop approval. Consequently, GM plants undergo extensive safety testing prior to commercialization.
Hundreds of millions of people across the world used up genetically modified crops since 15 years. And with no reported ill effects (or legal cases related to human health), despite many of the consumers coming from that most litigious of countries, the USA.
There is little documented evidence that genetically modified crops are potentially toxic. Rats fed with genetically modified potatoes expressing the gene for the lectin suffered damage to gut mucosa. The presence of foreign DNA sequences in food poses no intrinsic risk to human health. All foods contain significant amounts of DNA and RNA, consumed in the range of 0.1–1.0 g/day.
Advantages of Genetically Modified Crops
Food supplies become predictable.
When crop yields become predictable, then the food supply becomes predictable at the same time. Therefore this gives us the ability to reduce the presence of food deserts around the world, providing a greater population with a well-rounded nutritional opportunity that may not have existed in the past.
Nutritional content can be improved.
Genetic modifications do more than add pest resistance or weather resistance to GMO crops. The nutritional content of the crops can be altered as well, providing a denser nutritional profile than what previous generations were able to enjoy. This means people in the future could gain the same nutrition from lower levels of food consumption.
Genetically modified foods can have a longer shelf life.
Instead of relying on preservatives to maintain food freshness while it sits on a shelf, genetically modified foods make it possible to extend food life by enhancing the natural qualities of the food itself.
We receive medical benefits from GMO crops.
Through a process called pharming, it is possible to produce certain proteins and vaccines, along with other pharmaceutical goods, thanks to the use of genetic modifications. This practice offers cheaper methods of improving personal health.
It creates foods that are more appealing to eat.
Genetically modified foods improve the colors of the food to make it more attractive to eat. Deeper red colors make food seem to be sweeter, even if it is not. Better nutrition and enhanced flavors found in brighter foods.
Genetically modified foods are easier to transport.
Because GMO crops have a prolonged shelf life, it is easier to transport them greater distances. This improvement makes it possible to take excess food products from one community and deliver it to another that may be experiencing a food shortage. Genetically modified foods give us the opportunity to limit food waste, especially in the developing world, so that hunger can be reduced and potentially eliminated.
Herbicides and pesticides are used less often.
Herbicides and pesticides create certain hazards on croplands that can eventually make the soil unusable. Farmers growing genetically modified foods do not need to use these products as often as farmers using traditional growing methods, allowing the soil to recover its nutrient base over time. Because of the genetic resistance being in the plant itself, the farmer still achieves a predictable yield at the same time.
Disadvantages of Genetically Modified Crops
GMO crops may cause antibiotic resistance.
When crops are modified to include antibiotics and other items that kill germs and pests. Then the effectiveness of an antibiotic or other medication is reduces when it is needed in the traditional sense.
Farmers growing genetically modified foods have a greater legal liability.
Cross-pollination is possible between GMO crops and non-GMO crops as well, even when specified farming practices are followed. Farmers that do grow GMO crops could also face liabilities for letting seeds go to other fields or allowing cross-pollination to occur.
Genes go into different plant species.
Crops share fields with other plants, including weeds. There are different genetic migrations that usually occur. Interactions at the cellular level could create unforeseen complications to future crop growth where even the benefits of genetically modified foods may not outweigh the problems that they cause. One example: dozens of weed species are already resistant to atrazine.
Independent research is not allowed.
6 companies control most of the genetically modified foods market at the core level. Over 50% of the seed producers that have created the GMO foods market prohibit any independent research on the final crops as an effort to protect their profits.
Some genetically modified foods may present a carcinogen exposure risk.
A study showed that crops tolerant to commercial pesticides greatly increased the risk of cancer development in rats. The information from this research study, though limited, has been widely circulated and creates the impression that all GMO foods are potentially hazardous.
How does GM technology differ from other plant breeding techniques?
The era of scientific crop improvement date bake to around 1900, when the impact of Gregor Mendel’s studies on trait inheritance in peas became widely recognized. Since then, a broad range of techniques has been developed to improve crop yields, quality, and resistance to disease, insects, and environmental stress.
Most plant breeding programs rely on manual cross-pollination between genetically distinct plants to create new combinations of genes. The progeny plants are intensively evaluated over several generations and best one is selected. An example is a tomato variety.
Other techniques included within the conventional plant breeding toolbox are development of hybrid varieties by crossing two parental strains to produce offspring with increased vigor; and induced mutations to create useful variation.
Genetically modified technology is much more precise in that it transfers only the desired gene or genes to the recipient plant. Another branch of agricultural biotechnology distinct from genetically modified technology associated with favorable traits such as higher yield or disease resistance.
Despite the current uncertainty over GM crops, one thing remains clear. This technology, with its potential to create economically important crop varieties, is simply too valuable to ignore. There are, however, some valid concerns.
If these issues are to be resolved, decisions must be based on credible, science-based information. Finally, given the importance people place on the food they eat, policies regarding GM crops will have to be based on an open and honest debate involving a wide cross-section of society.