“GMOs- genetically modified organisms are any living entity constructed by altering their genetic composition, without affecting their normal function.”
In other words, it can be stated as,
“Organisms whose genetic material is altered using the recombinant DNA technology or gene therapy is known as GMO or genetically modified organisms.”
Plant breeding is not new for us. We know the economic importance of plants. However, the versatility of the breeding techniques has improved within the last 100 years.
GMOs are those whose genetic material is changed using genetic engineering techniques. Significant improvement in plant hybridization is done after the introduction of various sophisticated genetics and genomics techniques.
The GMO stands for “genetically modified organism”, meaning that something from an organism’s genome (plant, animal or bacteria) is changed or modified. But why are we doing modification in one’s genome?
In the present article, we will try to answer this question with some of the potential applications of GMOs in various fields. Furthermore, I will give you some of the popular and best examples of GMOs.
The aim of constructing GMOs is to either change organisms’ characteristics or producing a new variation in nature. Those changes are actually beneficial to us- humans.
For example, the insulin a type of protein is now produced using the recombinant DNA technology through the genetically modified bacteria. The genome of those bacteria is altered in such a way that as they grew, they produced insulin as a byproduct.
GMOs have tremendous application in agriculture, medicine, human science and animal research likewise.
Starting from primitive prokaryotes to higher eukaryotes, any living organism’s genome can be altered using artificial means,
However, their consequences are unknown and therefore, genetic engineering, gene editing and genome alteration are restricted for animals, especially for humans.
Genetic engineering experiments on humans are banned in almost all countries. Still, It’s agriculture values are unmatched. Genetically modified plant species or bacterial strains are created for various applications.
What is Genetically Modified Organism?
In 1973, Cohen S and Herbert B had constructed the world’s first genetically modified kanamycin-resistant bacteria.
Notably, the era of genetic engineering and recombinant DNA technology was commercialized after Flavr Savr tomato was constructed.
Using the antisense RNA technology, the ripening genes for tomatoes were silenced which facilitated delayed ripening. The newly created tomatoes named as “Flavr Savr” made transportation easy without damaging tomatoes.
Broadly, the process of GMO construction is like this,
Genes from two organisms of the same species, different species or from different genera are linked or joined to construct the recombinant DNA.
Using artificial vectors or plasmid, the newly formed DNA is inserted into the host organism.
PCR, DNA sequencing and microarray are various techniques implemented to validate the insert.
Related read: Plasmid DNA- Structure, Function, Isolation And Applications.
“By unnatural means or through genetic engineering, changing or altering an organism’s genetic composition without affecting its normal function is Known as GMOs.”
“Either prokaryotes or eukaryotes whose genome is altered in the laboratory using artificial techniques are known as genetically modified organisms.”
GMOs are created by genetic engineering techniques such as gene transfer, gene knockout or knockin and recombinant DNA. We have covered an amazing article that contains all the information and the entire process of how the recombinant DNA is constructed.
You can read the article here: What is genetic engineering?
Anyway, for understanding the present topic, it is very essential to understand the process of GMO construction. So here we are briefly explaining the process.
Selecting donor and recipient species is the first step in the process. Usually, the donor is a microorganism whose gene is being inserted into the recipient.
In the next step, the gene of interest, what we wish to express is isolated from the donor.
Now we are going to insert it into the recipient organism, let’s say we are using some plant species.
Inserting foreign DNA in the recipient genome is not easy, here, for doing it we are using a special type of gene transfer vehicle known as ‘vector’.
Usually, plasmid- a smaller-circular bacterial DNA is utilized as a vector. The gene of interest along with one selectable marker sequence is inserted into the plasmid.
Besides plasmid gene guns, particle bombardment and electroporation are some of the well-known techniques applicable in inserting DNA.
The newly formed DNA is now known as recombinant DNA.
It is then inserted into the host bacterium to infect the plant species. Agrobacterium tumefaciens is the first choice for transfection. The plasmid is injected into the A. tumefaciens and then it infects plant cells, afterwards.
Through tissue culture, the transformed cells are cultured. The whole new plant is generated from a few cells during tissue culture.
But before that, the insert is validated. Bacterium carrying only selectable markers with the GOI can grow in the medium.
Now the newly formed plant species are sent to the field for various field trials.
In the last step, the newly constructed plant species undergo several testing.
For example, the first test is performed to find out the insert. A technique called DNA sequencing which reads the DNA sequence of a plant to validate the presence of insert.
Other biochemical tests are also done to understand the function of a new gene.
The plasmid DNA mediated gene transfer is more popular among all because of its high efficiency, accuracy and transfection capabilities.
The process of genetic modification is done using various ways. Some of them are enlisted here,
- Inserting a gene from other organisms or species to introduce a new trait or function.
- Removing a gene from the organism to suppress the function of a gene.
- Replacing the faulty gene with a healthy one to improve the normal function.
- Replacing a whole genome with the new one to create a new variety.
GMO is tremendously valuable in agriculture, production of therapeutic drugs and molecules.
In-plant biotechnology and agriculture, pesticidal, herbicidal, drought, temperature, insecticidal and other abiotic stress-resistant plant species can be created.
Furthermore, in the same field, genetically modified plants are created to increase the quality, yield and nutrient values. Thus the cost of the product can be decreased.
Various disease resistance GM- plant species are constructed to fight against plant infections and diseases.
Bioplastic and biodiesel production is made possible due to genetically modified organisms. Biodegrade and fuel-producing bacterial strains are now developed through the present technique.
One of the powerful applications of GMO is in the gene therapy experiments. Transgenic animals or GM-animals are created to carry a human gene or mutation or DNA sequence.
The aim of it, is to study the function or effect of DNA or some gene on human health. In addition to this, through gene knockout or knockdown, gene expression can also be studied.
Therapeutic drugs, proteins, hormones, antibodies and other biomolecules are produced artificially by genetic engineering and GMO research.
Take a look at some of the classical examples of genetically modified organisms.
Cotton is one of the greatest economical important plants. The Bt-cotton is a genetically altered or modified cotton plant having insect-resistance capacity. In comparison with the natural cotton plant, the Bt-cotton can fight against the bollworm attack.
A Cry gene from the bacterial Bacillus thuringiensis was isolated and inserted into the cotton genome. Once the transgene is expressed in the host plant when ingested by the bollworm, it causes the death of worms.
The protein expressed by the Cry gene dissolves the gut lining of worms.
Flavr Savr tomato
The Flavr Savr tomato is one of the best examples of GMO so far. Bulk transportation of tomatoes was the biggest problem until the development of FS-tomato. Natural tomatoes spoil more quickly during transportation. The Flavr Savr tomato was developed using the antisense RNA technology which prevents the softening of fruits.
The PG gene encodes polygalacturonase, induces fruit ripening. The antisense RNA is created for the enzyme having an activity to suppress gene function. The inactivation of the enzyme prevents softening of tomatoes. This facilitates easy transportation.
E. coli for therapeutic proteins
In 1978, Herbert and Boyer developed artificial insulin protein through recombinant DNA technology. A gene for insulin inserted into the E.coli genome for the production of insulin. The genetically modified bacteria, E. coli, produces insulin as a byproduct. It is used to cure the diabetic patient.
In 1985, the human growth hormone was produced artificially by inserting the gene of growth hormone in E. coli.
The vaccines generated using the recombinant DNA or genetic engineering technique is known as recombinant vaccines. DNA vaccines and recombinant proteins are two broad categories of it.
Bacteria, yeast, insects and mammals are used to develop and produce recombinant vaccines.
One of the classic examples of it is the vaccine against Hepatitis B virus developed using the genetically modified yeast, Saccharomyces cerevisiae.
The Saccharomyces cerevisiae- a baker’s yeast is used to produce vaccines against Hepatitis B virus. The vaccine is known as recombinant vaccines.
The yeast genome is modified in such a way to produce vaccines based on the hepatitis B surface antigen. Ever since it was made, it is used to prevent hepatitis B.
We will discuss DNA vaccines and other examples of recombinant vaccines in some other article.
Yet another classic and well-known example of the GMO is the golden rice. The genetically modified rice variety was developed to overcome vitamin A deficiency.
More amount of beta-carotene in a rice plant is generated which is converted into vitamin A once consumed by us. And therefore, our natural requirements of vitamin A are completed.
Beta-carotene encoding genes are more active in green leaves than grains. However, by inserting two genes in rice’s genome, more beta-carotene is produced.
The plant’s gene for phytoene synthase and bacterial phytoene desaturase gene are recombined and inserted into the rice. Once it is expressed, more beta-carotene is produced in grains as well.
The amount of beta-carotene is 23 fold increased in golden rice.
As we know, various species of GMOs are created to attain economic boost. Salmon is one of the highest consumed fish in the world.
In 1989, AquaBounty technologies had developed a new genetically engineered variety of salmon in order to grow faster in less time.
The growth-hormone regulating gene of an Atlantic salmon is replaced with the same gene of Pacific Chinook salmon. In addition to this, to achieve high expression, a promoter sequence from the ocean pout is inserted in it.
The newly created salmon can grow year-around instead of in some specific season. Thus the market requirement of salmon can be satisfied.
Besides these, Bt brinjal, Bt tomato, GM maize, Bt corn, Herbicidal tolerance soybean, Virus resistance in plum and glow in the dark animal for various research purposes are some of the other examples of a genetically modified organism.
Note: plant species labelled as “certified organic” are natural ones, it doesn’t contain any genetically modified elements in it.
Common microbes used in GMO construction:
Selecting the donor microbe or organism is as important as developing new varieties. Selecting the wrong microbes can cause experimental failure and thus increase the research cost.
This is the reason, scientists are using some of the common types of microbes in the first trials while doing research on GMOs.
Furthermore, microbes can be cultured easily and their growth rate is rapid. We can say, it is a type of renewable source for GMO experiments.
E.coli and yeast are commonest among other microbes. However, some other model organisms are Bacillus, streptomyces, Lactic acid bacteria, Aspergillus and Corynebacterium.
Notably, these microbes don’t always give success.
Only FDA approved GMO products are distributed
Risk and controversies
GMOs is one of the most controversial topics nowadays. The unacceptance of Bt brinjal in Indian society is the classic example of how people react to the transgenic plant or food products.
It is believed that some of the GMO products are harmful to humans and can cause health-related issues in us. However, the supporting documents for this controversy are less.
Even though we are actually creating human-beneficial organisms by altering the genomic composition, some think that it is unethical, actually.
Some scientists believed that some transgenic plant species are harmful to other organisms. For instance, Bt corn. The transgene of Bt corn spreads through pollen into the surroundings. This one is the possible reason for the death of monarch larvae. Although the effect is very low.
Till date, no side effect of any Genetically modified plant product or other organism is reported.
However, due to the religious concern and conservative mindset, people of some groups avoid GMOs.
For instance, in India, people avoid using Bt brinjal because they think it is constructed using animal genes, although it is not true but as the majority of Indians are vegetarian, they avoid the use of Bt products.
Besides these, The GMO or genetically altered plant production companies want to copyright their products. And thus restricted their unethical use. Consequently, tt inversely influences smaller farmers who are not capable enough to purchase GM seeds.
GMO and IPRs
IPRs- intellectual property rights are very important in the field of genetic engineering and the production of genetically modified organisms.
The IPRs reserves one’s right to use its product. Products might be some GM-bacterial strain, some novel plant, byproduct or anything.
Scientists, organisations or companies doing research for years to construct something valuable and new. Thus, a huge investment is required to do so.
Using, trademark, trade secret, copyright or geological indication either new research or GMO is protected.
It doesn’t mean that no one can use it. One has to pay some amount in the form of royalty to the original developer, creator or scientists to use it. And it is obvious because they had invested huge money and time.
Under the trade secret, original creators or scientists can protect their new findings, documents, protocols, SOPs or other trade-related documents.
Trademark is given to protect unauthorised use of the title, name of branding.
The geological indications protect the misuse of landmark information.
Notwithstanding, intellectual property rights also adversely influence other small farmers and distributors.
The IPR is a huge topic, in fact. So we are not discussing all of its aspects here. These are some of the basic information one should know about the IPR.
Altering an organism’s genome is ethically wrong and against nature’s law, some think so. If GMO inversely affects the environment then it is wrong but if we are doing it only to improve human life quality then it is fair.
For instance, a high nutrient valued genetically modified plant can increase our health. However, as its outcomes are unknown to us, it can not be used for humans.
Bawa AS, Anilakumar KR. Genetically modified foods: safety, risks and public concerns-a review. J Food Sci Technol. 2013;50(6):1035–1046.