Transgenic Plants

In this article, I will explain to you what are Transgenic Plants and the common methods of transferring a gene to a plant. These methods allow genes with our desired and useful traits will be incorporated into the plant. You will also learn about the applications of transgenic plants in 2023 which have made a big impact on the agricultural and medical sectors.

Transgenic Plants

Transgenic Plants are those plants that have foreign DNA inserted in them by another specie through the process of genetic engineering. The foreign gene incorporated into the plant is known as a transgene. The most common transgenic plants are potatoes, corn, rice, cabbage, maize, wheat, etc.

How transgenic plants are produced?

Plants can be modified genetically by inserting DNA into their genome to develop a new trait. The new DNA gets incorporated into the genome creating a GM plant.

These transgenic plants are produced when the DNA is inserted into the plant cells. This specific DNA segment is transferred to the plant through a variety of methods.

There are two main types of methods: direct gene transfer, which can be performed through a gene gun, and electroporation. The other method is indirect gene transfer which is carried out through vector-based gene transfer known as Agrobacterium-mediated gene transfer

Direct Methods of gene transfer

Biolistic / Gene Gun

This is the most popular technique in which DNA and protein molecules are treated with gold and tungsten particles and then projected to target cells using a gene gun. The genetic material which contains the desired gene is directly inserted into the plant genome.

The target DNA segment whose surface is coated with metal particles serves as a microcarrier and is blasted into plant cells using a gene gun. The DNA is precipitated onto a metal microcarrier during this process. The metal particles are placed inside a plastic tube. The microcarriers are propelled by helium gas and then bombarded onto plant cells.

There is sufficient pressure of helium gas that enables it to make holes in the cell wall and insert genetic material containing the desired genes into the cell wall of plant cells. In this way, DNA coated with metal particles enters the plant. This technique is applied to both monocots and dicots. This is the most effective method of transferring the new genes of interest into many kinds of plants.

Electroporation

This is the direct method of transferring genetic material by electric current. This process operates by creating pores in the cell membrane from where the genetic material will pass to the cell.

First, the plant cells are treated in a medium containing foreign DNA. These cells are treated with specific chemicals to break the cell wall of the plant before applying an electric impulse. Then cells are prepared for electroporation by incubating at room temperature. After incubation, cells are imposed into the electrical field which helps to create holes in the cell membrane of plants. The target DNA can enter the plant through these pores.

The indirect method of gene transfer

Agrobacterium mediate gene transfer

One way of transferring DNA is taking a bacterium or virus and inserting DNA into the host cell by passing through various stages of the bacterial life cycle. The most common bacteria among transgenic plants are known as Agrobacterium tumefaciens. Agrobacterium is basically a soil bacterium. The technique applies to a variety of plants such as maize, wheat, and all the monocots.

In this method, we use a bacterial vector and insert the desired segment of DNA into the host. The particular gene is introduced into the bacterium cell and the bacterial cell transfers the transgene into the plant genome. The plants which have incorporated the genome allow it to propagate and develop into a new plants.

Its mechanism works when a plant is infected, Agrobacterium can detect any wound on the surface of a plant, which causes crown gall disease. At the same time, wounded plants emit chemicals that are detected by a bacterium that stimulates Vir proteins in the bacterial cell which produces Vir genes. These Vir genes break the DNA into a single strand producing T-DNA. T-DNA is a DNA that contains a gene of interest along with auxin and cytokinin present in the Ti plasmid.

This T-DNA strand is then carried by the plant cell and incorporated into the plant genome. Auxins and cytokinin, two plant hormones allow the plant cell to grow and propagate which results in crown gall tumor growth. Thus, by infecting plants with bacteria, DNA is transferred to plant cells. This is the first technique to take T-DNA from a tumor-inducing plasmid and produce recombinant T-DNA. This T-DNA carrying the foreign gene is inserted in the plant cell.

Transgenic Plants|Methods of gene transfer

Agrobacterium Mediated gene transfer

Applications of Transgenic Plants

Agriculture Sector

Applications of transgenic plants have played a significant role in the agricultural industry. Gene transfer is allowed for a variety of purposes such as enhancing agricultural production, providing resistance to insects, and pests, and developing crop tolerance.

Resistance against abiotic and biotic stresses

Disease-resistance genes are added to plants to develop resistance against those pathogens, bacteria, and viruses which induces stress in crop and also improve crop quality. Crops produced have improved resistance against biotic stress which includes insect-resistant crops, virus-resistant crops, and bacterial-resistant crops. Insect resistance crops provide resistance against pests such as Bt.

Abiotic stresses are caused due to environmental factors such as soil type, humidity, temperature, and water level. All factors changed due to climate change. Plants are given stress-tolerant genes to develop resistance against these climatic factors. Transgenic plants have been developed to provide resistance against herbicide which helps kill weeds and other unwanted plant parts for example the most common herbicide is glyphosate.

Increased Nutritional value

All the underdeveloped Nations are suffering from malnutrition. Plants are genetically modified undergoing a process of bio-fortification to produce crops that are rich in nutritional value such as golden rice, sweet potato, maize, etc.

Medical Industry

Transgenic plants have many uses in the pharmaceutical industry. Gene transfer in plants has been developing to manufacture proteins and compounds that could not be produced naturally. Transgenic plants have been able to produce recombinant proteins and edible vaccines.