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Transgenic Plants Examples, Definition, Procedure, Application

The term"transgenic plants" refers to plants whose DNA has been altered by genetic engineering. This implies that the genes of another species...

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This article writter by MN Editors on November 22, 2021

Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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Transgenic Plants Examples, Definition, Procedure, Application
Transgenic Plants Examples, Definition, Procedure, Application

Transgenic Plants Definition

  • The term”transgenic plants” refers to plants whose DNA has been altered by genetic engineering. This implies that the genes of another species is introduced and then merged in the genome of the plants that alters the features of the genome originally.
  • Although horizontal gene transfer is observed natural in the environment (between plants that are growing close to one another).
  • Different artificial methods are used to add gene sequences into plants with the intention of increasing yields and making them more resilient of various environmental conditions as well as making them resilient to certain biotic stresses or other environmental stresses.
  • This is why transgenic plants are extremely useful in agriculture as well in other industries (e.g. within the industry of pharmaceuticals).
  • The first transgenic plant was created in the year 1982. It was a plant of tobacco that was resistant to antibiotics.
  • The genetic material that is inserted into the gene of the plant could be taken by a completely different species, or from an entirely different species.

Transgenic Plants Examples

Since 1983 Genetic engineering has been applied to various types of plants to create desired characteristics. Particularly, these techniques are used to enhance specific traits of tomato, corn, soybean, banana, and tobacco, among other species of plants and crops.

Although there are many instances of plants that have been transgenic there are three major methods that are used to introduce genes into the plant cell. This includes:

1. Vector-mediated gene transfer (also known as indirect gene transfer or vector-mediated transformation)

The name implies this method uses vectors to carry certain genes in the cells of the target to allow them to be replicated and expressed. This permits the plant to display the characteristics desired.

Although some viruses are utilized to accomplish this Two members of the family Agrobacterium are typically chosen for this process. This is because they have proved to be effective in a broad range of plant species. Particularly, this method is utilized in many monocots, including maize wheat and barley to name a few.

In normal conditions in normal circumstances, the bacteria Agrobacterium tumefaciens (which naturally occurs in soil) is able to sense a cut on the plant’s surface and transfer certain genes of the cell of the plant, causing the disease known as crown gall.

The same mechanism is responsible for the bacteria Agrobacterium is the culprit behind hairy root diseases in a variety of plants. If the plant is injured by a bacterium, it releases specific molecules which are recognized by bacteria via a protein known in the form of VirA (located within the surface of bacterial cells).

After they have been identified that the protein is activated, it activates another protein called VirG within the cell, which triggers gene Vir in the bacteria genome. The activation triggers genes to create endsonucleases (VirD1 as well as VirD2) which break off at 25 base pair on the plasmid, releasing only one T-DNA strand. When it is connected to the endonuclease, VirD2 the strand is then transported to the plant cell, which is then embedded into DNA of plants.

While the expression of genes in the strand leads to the creation of various products, the most significant ones are the hormones cytokinin and auxin that cause plants cells to multiply rapidly.

This is why an increase in the size of the gall on the crown occurs. Alongside both hormones the expression of these genes results to the creation of opines that are the carbon and nitrogen needed by bacteria to survive.

Utilizing this method Scientists first collect the T-DNA before introducing the plasmid so that it can be easily modified. This is crucial because it permits a small DNA sequence which is adjacent to that transcription device to be changed with the gene that are of interest. The genes of interest are introduced into the plants cells via infection of the plant with bacteria.

The genes are integrated into the genome of plants and then expressed upon replication. Because the those genes that are of interest have been included in the plasmid expression of these genes do not cause negative results like tumors or the opines.

The following diagram is a representation of gene transfer via vectors:

vector-mediated gene transfer
Diagrammatic representation of vector-mediated gene transfer. Credit: MicroscopeMaster.com

2. Particle-mediated transformation (particle bombardment or gene gun method)

In contrast to vector-mediated transformation, where it is initially placed into a plasmid prior to it is introduced to the cell of the plant particle-mediated transformation is the process of directly inserting genetic material that contains genes of interest into the cells to allow it to become part of the genome in the plant.

To accomplish this there are a variety of metal particles are able to be used to bombard the gene gun. This includes gold, rhodium and tungsten to name a few. In this method genes (DNA) is then transferred to the metal microparticles (microparticles could vary between 0.45 and 1.5um in size).

In this instance the metal particles function as microcarriers since they carry genetic material that is to get into the cell of plant. These carriers are then encased in plastic tubes. The tube is cut into small tubes (which serve as cartridges) approximately 1/2 inch in length by using an instrument for cutting tubes. If the tubes cannot be utilized immediately, they are kept at temperatures of 4 degrees C.

It is crucial to make sure that the cartridges are stored in a tightly sealed vial with an ingredient that keeps the vial from drying. When they are ready to use the cartridges are placed into a cartridge holder that can accommodate around 12 cartridges. The holder for the cartridge is put in the gun and then secured to the gun.

Once the trigger button has been activated, an helium gas impulse is used to force the microcarriers in a way they can be able to attack cells in the plant. This helium gas pressure provides enough force that allows the microparticles/microcarriers to punch holes through the cell wall and introduce the genetic material into the cells.

In cells there are particles that could be found within the the cytoplasm while others are located within the nucleus. However the location, the genetic material is separated from the carriers, allowing it to interact in the genome of the plant cells to create desired traits.

Gene guns allow you to introduce new genetic material containing desired genes into cells of plants by with force, this method is applicable to a variety of kinds of plants, including monocots as well as dicots.

In one instance, the technology was used to transform the DNA of

  • Soybeans
  • Maize/corn
  • Barley
  • Onions
  • Rice
  • Melon

In contrast to vector-mediated gene transfer particle-mediated transformation, it is very easy to do and has been proven to be extremely efficient. Additionally it can be utilized in the process of introducing new genes to various kinds of plant cells in an extremely short time. This is among the top and most effective methods for gene transfer.

gene gun in action
Diagrammatic representation of a gene gun in action .Credit: MicroscopeMaster.com
  1. The pressure of the gas moves down the barrel
  2. The disc is damaged by pressure.
  3. The macrocarrier that contains DNA coated particles is stopped by stopping the screen
  4. DNA-coated particles enter the plant cells

3. Direct DNA absorption (gene transfer through electroporation)

As with particle-mediated transformations, direct DNA absorption via electroporation can also be a method for the transfer of genes. It is due to directly inserting genes into the cell of the plant without the need for the aid of a mediator (vector). In this case, the main goal is to make pores on the surface of the cell (also called electropores) by which genetic material can be introduced into the cell.

To perform this procedure plants being used for this procedure are placed in a buffer that has some foreign DNA. This is also known as a DNA bath. It helps prepare the cell for the electroporation. The temperature range and duration of incubation are determined by the type of plant cell and also the kind of DNA that is introduced into the cells.

After incubation after which the buffer is exposed to electrical impulses which create temporary pores in the cell membrane of the plant cell. Since the cells are immersed in a buffer which contains an outside DNA source, that DNA will then be able to easily get into the cell through the pores, before closing.

Since the technique is typically employed for protoplasts, some researchers initially employ chemical treatments to make pores that are present on the outer surface (cell wall) of plant cells prior to placing the cells under electroporation.

Yet, this technique is seldom used to alter plants because of the difficulties created by the cell wall.

the impact of electroporation on the cell membrane
Diagram showing the impact of electroporation on the cell membrane. Credit: MicroscopeMaster.com

Applications of transgenic plants 

When it comes to transgenic plants There are two main areas of application. They include:

For Agriculture

  • Since these methods involve altering the genetic data of plant species, the agriculture sector is one of the most important agricultural areas.
  • Since 1982, this technology has been utilized to alter the properties of various varieties of plants, from barley and corn to tomato and onion.
  • In this case, gene transfer is employed for many purposes that range from improving yields (crops and animal feeds, etc.) and also to increasing crop and plant tolerance to various environmental and biological aspects.

Biopharming/Pharmaceutical Industry

  • Aside from the agricultural industry, the gene transfer process in plants has also been found to have numerous ways to be used in pharmaceutical research. 
  • Gene transfer is used to produce large quantities of various chemicals and proteins which plants cannot naturally produce naturally.
  • When compared with the other types of cells utilized in biopharmaceuticals and biotechnology, transgenic plants are thought to be more efficient in terms of cost. 
  • In addition, they put installed the technology which can convert molecules into specific structures that are able to perform the biological functions that are required.

Role of Transgenic Plants as Bioreactors or Biofactories

  • Like many other cells, plant cells possess biological mechanisms involved in different processes. In this case, the information (blueprint) necessary to carry out these processes is stored inside the gene material.
  • Through the introduction of fresh information, in terms of new genes it is now possible for scientists to make use of these processes to create a variety of proteins, including antibodies and vaccines in addition to others.
  • Although bacteria and different kinds of organisms have previously been utilized as bioreactors Transgenic plants are receiving greater attention over the last few times because they are more affordable and have the capability of post-translational changes that are involved in the creation complicated proteins.

Advantages of Transgenic Plants 

The methods and technology used to make transgenic plants are utilized across a variety of industries and sectors. The reason is that transgenic plants have many advantages when compared to natural plants. The main advantages of transgenic plants are:

They are resistant to various biotic and abiotic stress 

Biotic stresses are those caused by other living organisms ( bacteria, viruses, fungi and so on) while Abiotic stresses are those types of stresses that arise from the environment in which the plants are grown.

Through the introduction of certain genes, scientists have been able to create a variety of crops and plants resistant to these stresses. Through this process farmers are able to stay away from the high cost of crop damage that result from biotic and other stressors.

Increased yields

The benefit to transgenics is they offer higher yields than natural plants. In general there are two primary reasons for why these plants produce higher yields. The first is that it is possible for scientists to create genes that alter crops, which results in higher yields than natural crops or plants.

In addition, by introducing genes that enable the plant to resist environmental stressors both biotic and abiotic, the plant is able overcome different environmental conditions that could otherwise cause major harm to the plant.

High quality of yields

Quality of yields one of the main benefits of transgenic plants is that they yield higher yields of high quality. As previously mentioned, there are a variety of stressors found in nature that alter the growth of plants and yields. Furthermore, the different chemicals that are used for reasons to control pests, insects and weeds have also been found to have an effect on plants with sensitive sensitivity.

With gene transfer, researchers have successfully introduced new characteristics to different kinds of plants that allow them to resist the stresses. This is why the plants have high-quality yields since they aren’t significantly affected by the factors that affect other plants or their yields.

Although there are health and environmental concerns raised by the people, no conclusive evidence that these plants could be hazardous.

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Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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