How is Transgenic Plant (BT Cotton) produced? (Science Exhibition 2016) (English) (1080p HD)

Bt cotton is a genetically modified organism (GMO) cotton variety, which produces an insecticide to bollworm.

Strains of the bacterium Bacillus thuringiensis produce over 200 different Bt toxins, each harmful to different insects. Bt toxins are insecticidal to the larvae of moths and butterflies, beetles, cotton bollworms and ghtu flies but are harmless to other forms of life.

The gene coding for Bt toxin has been inserted into cotton as a transgene, causing it to produce this natural insecticide in its tissues. In many regions, the main pests in commercial cotton are Lepidoptera larvae, which are killed by the Bt protein in the genetically modified cotton they eat.

Bt cotton is ineffective against many cotton pests such as plant bugs, stink bugs, and aphids; depending on circumstances it may be desirable to use insecticides in prevention.

Bt cotton was created through the addition of genes encoding toxin crystals in the Cry group of endotoxin. When insects attack and eat the cotton plant the Cry toxins are dissolved due to the high pH level of the insect's stomach.

In 2002, a joint venture between Monsanto and Mahyco introduced Bt cotton to India.

Advantages of Bt cotton over non Bt Cotton

Bt cotton has several advantages over non-Bt cotton.

• Insects belonged to Lepidoptera (Bollworms) are sensitive to crystalline endotoxic protein produced by Bt gene which in turn protects cotton from bollworms.
• Reduction in insecticide use in the cultivation of Bt cotton in which bollworms are major pests.
• Reduction in environmental pollution by the use of insecticides.
• Bt cotton exhibit genetic resistance or inbuilt resistance which is a permanent type of resistance and not affected by environmental factors. Thus protects crop from bollworms.
• Bt cotton is eco friendly and does not have adverse effect on parasites, predators, beneficial insecticides and organisms present in soil.
• No health hazards due to rare use of insecticides (particularly who is engaged in spraying of insecticides).

Bt cotton has some limitations.
• High cost of Bt cotton seeds as compared to non Bt cotton seeds.
• Effectiveness up to 120 days, after that the toxin producing efficiency of the Bt gene drastically reduces.
• Ineffective against sucking pests like jassids, aphids, whitefly etc

How Bt cotton is developed?

Once identification of bollworm inhibiting genes has been achieved, molecular biologists have step by step solved the problems to achieve perfect transgenics. In case of cotton, Agrobacterium-mediated gene transfer technique has been essentially used.

There are four important methods of foreign gene (DNA) transfer in crop plants viz. plasmid method, particle bombardment, direct DNA uptake and micro-injection. These methods are also known as systems of DNA delivery for genetic transformation.

There are two main advantages of Agrobacterium mediated DNA transfer method. Firstly, this method has some control over the copy number and site of integration of transgene which is not possible in particle bombardment method. Secondly, this is a cheaper method of genetic transformation than particle bombardment method.

The particle bombardment method in which the foreign DNA is delivered into plant cells through high velocity metal particles, has some advantages over the Agrobacterium mediated method of DNA transfer. This method does not exhibit host specificity. Hence, it can be effectively used for the development of transgenic plants in various plant species. Moreover, this method is technically simple than Agrobacterium mediated DNA transfer method. In this method, there is no need of isolating protoplast.


Single gene traits cause least disruption of the existing plant genome and are much easier to develop in subsequent breeding efforts. Two components are required to accomplish genetic engineering. The first is the knowledge of plant genomic structure and the structure of a single gene, and the second is the ability to develop a complete plant from a single cell (regeneration).

Note :

1) In 2011, India grew the largest GM cotton crop at 10.6 million hectares. By 2014, 95% of cotton grown in India was GM.
2) India has bred Bt-cotton varieties such as Bikaneri Nerma and hybrids such as NHH-44.
3) Plants with the Bt toxin gene produce their own toxin and thus can kill caterpillars throughout the season without being sprayed with insecticide. Because the toxin is lethal to caterpillars, but harmless to other organisms, it is safe for the public and the environment.

Consideration :

1) Punjab Agricultural University (PAU) has successfully developed the country’s first Bt cotton varieties.
2) ICAR has identified three varieties namely PAU Bt 1, F1861 and RS 2013 for cultivation in Punjab, Haryana, Rajasthan. It is a cheaper alternative to Bt cotton hybrid seed.

Bt insect resistance technology can bring many benefits to crops, farmers, and consumers alike.