Bt corn is a genetically modified maize which has been developed by using the techniques of biotechnology. This corn is poisonous for the insects because a special kind of protein is expressed in its genome which is derived from a bacterium Bacillus thuringiensis. Bacillus thuringiensis is a soil bacterium which increases the soil fertility. The expressed protein is harmful and poisonous for the microorganisms but is useful for the humans and animals. The protein is able to code for a toxin which is when eaten by an insect, it crystallizes in the digestive tract of insect larvae and results in the starvation of the organism. It is also able to produce many insecticidal compounds which are also called as Bt toxins. These toxins reduce the use of pesticides in corn plants.

Method to develop Bt Corn:-
To make the corn genetically modified, a bacterium bacillus thuringiensis is used as a donor organism. The gene of interest that Bt delta endotoxin is taken from it which codes for a protein. This protein has the ability to kill the larvae of the insect. When a gene of interest is inserted in some other organism to see particular traits, it is necessary to insert some additional components also, so that the function of the desired gene can be observed properly. When we talk about the Bt corn, then the gene of interest is inserted in the following way.

Protein Gene:-
The gene of interest which codes for a particular protein in inserted in the genome of the corn. Bt genes produce Cry proteins in the corn.

Along with the Bt gene, a promoter is also inserted into the corn. The function of the promoter is to control the Cry protein and it also sees that how much protein is produced by the plant. Sometimes, the protein produces in some particular parts of the plant such as leaves, pollen or tissues but in some cases the desired protein produces in the whole plant.

Genetic Marker:-
Genetic markers are used by the seed companies to see the transformation of the protein in the plants. Some genetic markers include antibiotic resistance or herbicide resistant markers.

All the three components are inserted into the plant through various biotechnological techniques. Gene gun is one technique which is used for this purpose. The site where the whole package is inserted may affect the production of protein and it may be able to affect the plant's other functions. For this reason, the scientists have to carefully insert the Bt protein and should ensure the its sufficient production.

Mode of Action:-
When the corn plant grows along with new protein expressed in it, now it is able to attack the insects which eat it. It is during the larval stage of the insect, that most of the damage occurs to the corn crops. When the insects eat a particular part of the plant which contains the Bt protein, it attaches to the wall of the gut of the insect. As a result, the insect is unable to feed itself because due to the Bt protein, the gut wall breaks down and the normal gut bacteria attacks the body cavity of the insect. The insect starves due to the multiplication of the bacteria in its blood and dies ultimately.

Though Bt corn is harmful for the insects but it is beneficent for the humans and other animals like fish and birds. It is also environment friendly.

Benefits of Bt Corn:-
Due to the presence of a protein in the Bt corn from Bacillus thuringiensis, it is able to kill many insects which are harmful for the plant. The productivity of the corn crops increases and it can be beneficent economically. It is not toxic to humans and provides nutrients which are useful for their health.

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