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Transgenic Plants

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What are Transgenic Plants?

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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.

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