Bt crops are genetically modified crops. Bt is a gram-positive soil bacteria that produce insecticides naturally. The insect-resistance soil bacteria is known as Bacillus thuringiensis. The bacteria produce insecticides when oxygen and nutrients are insufficient for their vegetative growth. At this time bacteria, sporulates and spore contains one or more insecticides. Bt bacteria produces three types of insecticides proteins namely cry proteins, cyt proteins, and vip proteins. These three proteins' insecticides are effective against different types of insecticides. Although these three components are effective against insecticides cry protein is considered to be the most effective for commercial Bt formulation.
To produce these Bt crops advanced genetic engineering is used. In this technique, scientists insert the DNA of the Bt bacteria into the desired crops. So that Bt crops produce the same insecticides as Bacillus thuringiensis (cry protein) and are effective against pests.
In India, Bt cotton was introduced in the year 2002 with a joint venture of Mahyco and Monsanto companies. India generated the largest quantity of Bt Cotton in the year 2011. This cotton successfully destroyed the desired pests. While Bt Brinjal is generated after BT Cotton in the year 2008. It is introduced by Mahyco famous hybrid seed company located in Maharashtra. The Bt Brinjal was resistant to fruit and shoot borer that destroys about 90% of fruits.
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Bt crops are of various types. Some of them are described below
Bt Cotton − It is a genetically modified cotton plant. The Bt cotton is effective against insecticides and bollworms. Its genes are modified with Bt genes of the bacteria Bacillus thuringiensis so that they can produce their own microbial protein. The genes of Bt bacteria are inserted into the cotton plants. Bt Cotton also produce insecticide after inserting bacteria genome that generally they cannot produce. When the specific population of pests especially bollworms consumes the Bt cotton the worms become drowsy and sluggish and finally they lead to death. As the toxins generated by the crops are harmful to the worms.
Bt Brinjal − Bt Brinjal is generated by genetic modification. The Bacillus thuringiensis protein gene cry1 Ac is inserted into the brinjal plants. Bt Brinjal also becomes insect resistant after inserting the genome of bacteria. This brinjal crop is genetically modified to fight against Lepidopteron insects. When the particular insects eat the plants their digestive system is affected finally the insects die.
Bt Maize − The Bt maize is effective against the corn rootworm Diabrotica virgifera. This is popularly known as a billion-dollar bug. To produce Bt Maize same procedure is followed as Bt Cotton and Bt Brinjal. The genome of Bacillus thuringiensis is inserted into the maize plants. So they are effective against specific types of pests.
Bt Corn − It generates insecticides that effectively against pests. It can produce toxins continuously over a period of time so it extends its protective effects. It is the best alternative to using chemical insecticides. It is eco-friendly. Most of the Bt toxins are effective against a special group of caterpillars.
To produce the Bt crop following steps should be followed
Selection − To produce a Bt crop variety, scientists selected the genes for the specific Bt toxins.
Copy − They copy the desired traits genes. For example, if they want to produce Bt Cotton, they have copied the genes from soil bacteria that produce insect-resistance traits. The insect-resistance soil bacteria is known as Bacillus thuringiensis.
Insert − The third step is that scientists would insert the desired gene into the DNA of the plant at the embryo stage. As result, the cotton plant will be insect resistant as it contains the gene of Bacillus thuringiensis. Other characteristics of the plant will remain the same after inserting the desired traits.
Grow − The new cotton plant will be grown in a laboratory condition using the tissue culture technique. So that the cotton plants adopted the insect resistance traits. If this is successful scientists would allow the new Bt crop plants into greenhouses, small fields, and large fields accordingly.
Since the year 1996, the plants have been genetically modified with Bt (Bacillus thuringiensis). It is a soil bacteria that produce protein insecticides. By this method, the transgenic plants can produce their own insecticide protein. The Bt crops reduce the use of pesticides. Bt corn, potato, and cotton were grown across the world in the area of 29million acres across the world.
Bt microbial preparations are safe and effective but they are less effective than the Bt crops. These Bt microbial preparations have disadvantages like effectiveness is reduced in the sunlight and may be washed off during rain. They require considerable water, heat, and feedstock to produce, and must be manually applied, either by hand sprayer on small plots or by machine if applied to large tracts. These limitations of Bt microbial preparation lead to the introduction of Bt crops. The Bt crops can produce protein insecticides throughout the growing season. Most of the commercially approved Bt crops are corn and cotton.
Q1. What is bacteria?
Ans. Bacteria are unicellular microorganisms. They have a cell wall but do not have a definite nucleus like eukaryotes. The genetic materials are scattered in the cytoplasm. They are mainly found in soil, water, rock, etc. Bacteria have both positive and negative effects.
Q2. What do you understand by genes?
Ans. Genes are heredity material. Genes are constituted of deoxyribonucleic acid. In humans, genes vary in size. Rarely do the genes give instructions for protein synthesis. But most of the genes are not coded for protein synthesis.
Q3. What do you understand by bacterial spores?
Ans. Bacterial spores are small oval spherical in shape. The spores when produced internally it is known as endospores. The bacterial cell responsible for producing spores is known as a vegetative cell. In adverse conditions, bacteria produce spores that are resistant to unfavourable environmental conditions.
Q4. What is genetic engineering?
Ans. It is a laboratory process in which the genetic material of a species is altered with the desired traits.
Q5. What is fruit and shoot borer?
Ans. It is a type of insect (Leucinodes orbonalis) that affect mostly eggplants. The larvae of Leucinodes orbonalis damage shoots and fruits.
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