What Makes Transgenic Plants Important in Modern Biology?
Transgenic plants definition includes those plants which have one or more genes from another species introduced into their genome through genetic engineering processes. The biolistic method, in which a heavy metal coated with plasmid DNA is shot into cells, and Agrobacterium tumefaciens-mediated transformation is two techniques.
Transgenic plants include maize, rice, brinjal, cabbage, cauliflowers, potato, and tomato. The goal is to give the plant a new characteristic that does not arise naturally in the species. In this article, we will study more about the development of transgenic plants and various methods used for their development.
Transgenic Plants
Transgenic plants are those that are created by inserting foreign DNA into a cell and regenerating a plant from the cell.
Genetic engineering techniques are used to change the DNA of transgenic plants.
The goal of introducing a gene combination into a plant is to increase its productivity and usefulness.
This technique offers benefits like extended shelf life, increased yield, improved quality, pest resistance, heat, cold and drought tolerance, as well as resistance to a range of biotic and abiotic challenges.
Additionally, foreign proteins of commercial and medicinal value can be expressed in transgenic plants.
Golden rice is one of the transgenic plants. The rice plant, which makes beta carotene, is given the beta-carotene gene. The most common source is carrots, which when added to rice plants begin producing beta-carotene. Golden rice is fortified with vitamin A to increase its nutritional value because beta carotene is one of the precursors of vitamin A.
Bt-cotton is an additional form of the transgenic plant. The Bt-gene originates from bacteria and can be inserted into the cotton plant. The Bt-toxin, which is produced by this gene and is not hazardous to people, kills the bugs that feed on cotton plants.
Development of Transgenic Plants
In a lab, the genetic makeup of a plant is changed, typically by adding one or more genes from its genome, to create genetically modified plants. The new transgenic DNA is intended for the plant cell’s nucleus. The biolistic method (particle gun method) or Agrobacterium tumefaciens-mediated transformation method is used to create the majority of genetically modified plants.
1. Biolistic Method
Gene gun delivery of macromolecules DNA, RNA and proteins to the target cell involves the coating of macromolecules with micro-carrier particles such as gold and tungsten. They are then introduced into the target cell with high velocity, using an electric pulse or pressurised helium pulse. Such technique involved with the delivery of microprojectile is referred to as biolistic.
The major limitation of this technique is that the DNA is randomly introduced into the target cell.
2. Agrobacterium Mediated Transformation Method
The “agrobacterium” approach is the following technique for creating genetically modified plants. Agrobacterium tumefaciens, a soil-dwelling bacterium, is used in this process. It has the capacity to spread a piece of its DNA into plant cells. Through a tumour-inducing plasmid, the DNA fragment that infects the plant gets incorporated into a plant chromosome (Ti plasmid). The plant’s cellular machinery may be controlled by the Ti plasmid, which can then exploit it to produce numerous copies of its own bacterial DNA. A sizable circular DNA particle called the Ti plasmid replicates separately from the bacterial chromosome.
This plasmid is significant because it has areas of transfer DNA (t DNA) where a researcher can introduce a gene that can be transferred to a plant cell using a method called “floral dip.” A floral dip entails dipping flowering plants into an agrobacterium solution that contains the desired gene and then harvesting the transgenic seeds straight from the plant.
This strategy is advantageous since it is regarded as a more acceptable technique due to its natural manner of transfer. Additionally, “agrobacterium” is extremely effective at moving big DNA pieces. The fact that not all significant food crops can be infected by these bacterias is one of the agrobacterium’s main drawbacks. This approach works exceptionally well for the dicotyledonous plants like potatoes, tomatoes and tobacco plants.
Importance of Transgenic Plants
Insecticidal Resistance: A number of insect pests are harmful to the bacterium Bacillus Thuringiensis. It creates a protein toxin that is the mediator of its fatal impact. The toxin gene can be delivered directly into the plant’s genome using recombinant DNA techniques where it is produced and protects the plant from insect pests.
Virus Resistant Plants: By adding viral coat proteins, TMV-resistant tomato and tobacco plants can be created. Other viral-resistant transgenic plants include:
Potato virus-resistant plants
Rice that is resistant to RSV
Black gram that is resistant to YMV
Green gram that is resistant to YMV; among others
Herbicidal Resistance: Herbicide-resistant plants are those that can withstand herbicides. Many broad-range herbicides contain glyphosate as an active component. To produce glyphosate-resistant transgenic tomato, potato, tobacco, and cotton, the aroA gene from Salmonella typhimurium is inserted into a glyphosate EPSP synthase. To create tobacco plants resistant to E. coli sulphonylurea, the mutant ALS (acetolactate synthase) gene from Arabidopsis is transformed. To create atrazine-resistant transgenic plants, QB protein of photosystem II from mutant Amaranthus hybrids is introduced into tobacco and other crops.
Nutritional Benefits: Every year, 500,000 kids lose their vision completely or partially due to vitamin A deficiency. For a sizable portion of the world’s population, milled rice serves as their main source of nutrition.
Crops with a high concentration of vitamin A cannot be produced using traditional breeding techniques. Three genes, two from daffodils and one from a microbe, have been inserted into rice by researchers. Transgenic rice has yellow-coloured seeds and produces more beta-carotene, which is a precursor to vitamin A. Such golden or yellow rice may be an effective remedy for the issue of vitamin A insufficiency in young infants living in tropical regions.
Conclusion
Genetic Modification is a technology that involves inserting DNA into an organism's genome. New DNA is transferred into plant cells to create a genetically modified plant. Typically, the cells are grown in tissue culture and eventually develop into plants. The new DNA will be passed down to the seeds produced by these plants. Transgenesis allows for the enhancement of nutrients in animal products, including their quantity, overall quality, and specific nutritional composition. Transgenic technology could be used to transfer or enhance nutritionally beneficial traits.
FAQs on Transgenic Plants: Process, Benefits & Examples
1. What are transgenic plants? Provide some common examples.
A transgenic plant is one that has been genetically modified using recombinant DNA technology to introduce a new, desirable trait. This involves inserting a specific gene from another organism (like a bacterium, virus, or even another plant) into the plant's genome. Examples include:
- Bt cotton, which is resistant to bollworm pests.
- Golden Rice, enriched with Vitamin A.
- Flavr Savr tomato, with delayed ripening.
- Herbicide-tolerant soybean, which can withstand specific weed-killing chemicals.
2. What is the main importance of developing transgenic plants in agriculture?
The primary importance of transgenic plants is to improve agricultural productivity and food quality. This is achieved by introducing traits that:
- Increase crop yield by making plants resistant to pests, diseases, and environmental stresses like drought.
- Enhance nutritional value, as seen in Golden Rice, which helps combat vitamin deficiencies.
- Reduce reliance on chemical pesticides and herbicides, leading to more sustainable farming practices.
- Improve food processing qualities, such as delaying the ripening of fruits to extend shelf life.
3. How does a Bt cotton plant protect itself from bollworms?
A Bt cotton plant protects itself from bollworms because it contains a gene from the bacterium Bacillus thuringiensis (Bt). This gene, called the cry gene, produces an inactive crystalline protein (protoxin). When a bollworm ingests parts of the plant, the alkaline pH in its gut activates the protoxin. The active toxin then binds to the surface of the bollworm's midgut cells, creating pores that lead to cell swelling, lysis, and ultimately, the death of the pest.
4. What is Golden Rice and why is it considered a significant transgenic crop?
Golden Rice is a genetically modified variety of rice (Oryza sativa) that is engineered to produce beta-carotene, a precursor to Vitamin A, in its edible grain. It is significant because it was developed as a public health tool to combat Vitamin A deficiency (VAD), a widespread issue in many developing countries that can lead to blindness and other health problems, particularly in children.
5. What was the first commercially grown transgenic plant?
The first genetically modified crop to be commercialised was the Flavr Savr tomato, which was approved for sale in 1994. It was engineered to have a longer shelf life by slowing down the ripening process. The gene responsible for producing the softening enzyme, polygalacturonase, was suppressed using antisense RNA technology.
6. How does RNA interference (RNAi) work to create pest-resistant transgenic plants?
RNA interference (RNAi) is a natural cellular process that silences specific genes. To create pest-resistant plants, scientists introduce a gene into the plant that produces a double-stranded RNA (dsRNA) complementary to a vital mRNA sequence in the target pest (e.g., the nematode Meloidogyne incognita). When the pest feeds on the plant, it ingests this dsRNA. Inside the pest's cells, the dsRNA is processed and triggers the RNAi pathway, which finds and destroys the pest's own complementary mRNA. This prevents the translation of a crucial protein, leading to the pest's death.
7. What is the difference between a genetically modified plant and a hybrid plant?
The key difference lies in the method of genetic alteration. A hybrid plant is created through traditional cross-pollination between two different but related parent plants, combining existing genes from the same or closely related species. In contrast, a genetically modified (GM) or transgenic plant is created in a lab using recombinant DNA technology, where a specific gene from an entirely different species (e.g., a bacterium) is inserted into the plant's genome to introduce a new trait that could not be achieved through conventional breeding.
8. Can transgenic plants be used as 'bioreactors' to produce pharmaceuticals? Explain with an example.
Yes, transgenic plants can be used as 'bioreactors' or 'molecular farms' to produce valuable proteins, enzymes, and pharmaceuticals. This concept is known as molecular pharming. For example, efforts have been made to produce the anticoagulant hirudin (originally from leeches) in the seeds of the transgenic plant Brassica napus (oilseed rape). The plant is engineered to synthesise and accumulate the desired protein, which can then be harvested and purified for medical use, offering a potentially cheaper and more scalable production method.
9. What are some of the ethical concerns and potential risks associated with transgenic plants?
The main ethical concerns and potential risks of transgenic plants include:
- Impact on Human Health: Concerns about potential allergens or unexpected toxic compounds being produced in GM foods.
- Environmental Risks: The possibility of gene flow from GM crops to wild relatives, creating 'superweeds', and the potential harm to non-target organisms (e.g., pollinators).
- Loss of Biodiversity: Over-reliance on a few GM crop varieties could reduce genetic diversity in agriculture.
- Socio-economic Issues: Dominance of large corporations in the seed market and issues related to patenting life forms.
10. What is the advantage of creating herbicide-tolerant crops?
The primary advantage of creating herbicide-tolerant crops is to simplify weed management. These genetically modified plants are resistant to a specific broad-spectrum herbicide. This allows farmers to spray the herbicide over their entire field to kill weeds without harming the actual crop. This method can reduce labour costs, decrease the need for tilling (which helps conserve soil), and allow for the use of more effective and often less environmentally persistent herbicides.
