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BT Crops are genetically modified plants that have been created to protect them from insects, parasites, and other pests. They are also known as Bacillus thuringiensis.
- BT Crops will produce the same toxin material as that of the bacterium.
- It is a soil-dwelling bacterium which is most commonly used in biological pesticides worldwide.
- The bacterium in these types of crops secretes a special protein, which is called cry proteins.
- These proteins are harmful to insects and other animals.
- Japanese sericultural engineer Ishiwatari Shigetane first designed the crops.
- Tobacco was the first crop to benefit from BT Crops.
- These types of crops degrade within a week or sometime in one day.
Key Terms: BT Crops, Genes, Crops, Bacillus Thuringiensis, Genetic, Insects, Pesticides, Cells, Pests, Bacteria, Plants, BT Cotton, BT Brinjal, Genetically Modified Crops
What Are BT Crops?
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BT Crops are transgenic plants that have been created by the DNA of the bacterium Bacillus thuringiensis. It will produce the toxin in plant cells, preserving the crops from pests.
- When an insect feeds on transgenic plants, the cry protein present will crystallizes in the insect's digestive system.
- They will eventually lead to the killing of insects.
- It has no negative effects on the human digestive system.
These crops are resistant to pests because they contain bacillus thuringiensis endospore or crystal toxins. Humans can implant the BT gene inside plant seeds thanks to the power of transgenics.
- These crops block the digestive system of insects, thus starving those insects.
- They are applied in the form of spray or through genetic engineering.
- It has been observed that 185 million hectares across the world grew BT Crops.
- Eggplants, corn and cotton are some commonly used crops in this category.
BT Corn
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Bacillus Thuringiensis
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Bacillus thuringiensis is a gram-positive, spore-forming bacterium found primarily in soil. It produces proteins that are toxic to insects. Organic farmers spray this bacterium solution on their plants to protect them from pests.
- The use of Bacillus thuringiensis began in 1996 with small quantities of the bacterium's genes.
- This aided in the production of cry proteins in plant cells, which assisted in the killing of pests.
- It comes from a natural source named biopesticide.
Pests such as the European and Southwestern corn borer, tobacco and cotton budworm, pink bollworm, and Colorado potato beetle decimated crop yields. Bacillus thuringiensis shielded the crops from such pests.
- There are different types of BT Crops which affect different insect groups differently.
- The spores of this bacterium will damage the gut of insect larvae.
- It is determined that insect gut has a pH value of 9.0 to 10.5.
- The toxins will break the lining of the guts of insects.
What are Genetically Modified Crops?
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Genetically Modified Crops addressed the severe food scarcity that many developing and developed countries faced due to shrinking agricultural land and low harvest levels in the late twentieth century.
- The DNA of these crops are modified using genetic engineering methods.
- GM crops use transgenics ushered in a new era of agriculture, and BT crops are one such advancement.
- To produce a GM crop, new DNA is inserted into cells of the required plant.
- Cells are converted into grown tissue, which is transformed into plants.
- The most common method for the generation of Genetically Modified Crops is the gene guns method.
Types of BT Crops
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BT Crops are divided into two categories which are as follows:
BT Cotton
The BT cotton variety is genetically modified with the BT gene to protect the plants from bollworm, a major pest of cotton. Worms on the leaves of BT cotton become lethargic and sleepy, causing less damage to the plants.
- When the worms consume the plant, they consume the toxic proteins produced by the crops, killing them.
- Since 2014, India has been the world's largest producer of BT cotton.
- These types of crops will eliminate the need for large amounts of broad-spectrum insecticides.
- Monsanto and MAHYCO launched the product in 2002.
- The most common advantage of BT Cotton is an increase in the yield of crops.
BT Cotton
BT Brinjal
BT brinjal is also developed through the genetic transformation of the bacterium Bacillus thuringiensis crystal protein gene cry 1 Ac. It was created to provide insect resistance against lepidopterans.
- BT genes produce proteins that bind to receptors on the insect's membrane.
- It results in the formation of pores on the membranes.
- This disrupts the digestive process and causes the insect to die.
- However, this crop has created much debate in India.
- BT Brinjal will reduce the usage of pesticides for cultivation by 80%.
Varieties of BT Brinjal
BT Crops In India
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BT brinjal was one of the first genetically modified insect-resistant plants in India. The Maharashtra Hybrid Seed Company, or MAHYCO, was the first to introduce it.
- Monsanto, one of the world's largest and most contentious seed companies, assisted MAHYCO in developing the product.
- It also has a significant stake in this Indian company.
In India, eggplant or brinjal agriculture has frequently been hampered by a major pest: the eggplant shoot borer, Leucinodes, orbonalis. This risk and the amount of insecticide required to keep the borer at bay are two reasons why BT brinjal has been promoted in India.
- This brinjal seed contains a specific gene, cry 1 Ac, that protects it from pests.
- It will act as a resistance to antibiotics.
- This crop will lead to the extinction of species from the ecosystem.
Advantages of BT Crops
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The advantages of BT Crops are as follows:
- BT Crops aids in increasing crop yield and, as a result, farmer income will increase.
- They aid in the control of soil pollution by reducing the use of synthetic pesticides.
- BT crops aid in the protection of beneficial insects.
- Since yields are increased in a short period of time, it can easily feed an increasing population.
- As pesticides are reduced, it results in the production of disease-free crops.
- It increases productivity in a small area of land.
Disadvantages of BT Crops
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The disadvantages of BT Crops are as follows:
- BT crops are more expensive than naturally grown crops.
- It has the potential to disrupt the natural process of gene flow.
- Pests may develop resistance to the toxins produced by these crops, resulting in decreased crop production.
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| Vegetative propagation in plants | Small Intestine | Mitosis |
Things To Remember
- BT crops are genetically modified plants that have been engineered by inserting the DNA of the bacterium Bacillus thuringiensis.
- These types of crops are toxic to herbivorous insects.
- The protein produced by the crops will bind to the receptor of the insect's membrane.
- Using cry toxins, BT cotton can withstand mothball, beetle, and butterfly larvae attacks.
- BT Genes were first designed by the Belgian company Plant Genetic Systems in the year 1985.
Sample Questions
Ques. Why was BT cotton developed? What is transgenic bacteria? Use any one example to demonstrate? (3 marks)
Ans. Transgenic cotton was developed about ten years ago by inserting the BT gene into the plant DNA, which produces toxins that kill the caterpillar. Toxins released by the plant would paralyze the caterpillar's gut when it fed on the plants.
- Transgenic bacteria are bacteria that have a gene or genes from an unrelated organism incorporated into their genome.
- When the human insulin gene is introduced into an isolated plasmid of E.coli bacteria.
- This recombinant DNA is transferred into a fresh bacterium, the latter is said to be transgenic or transformed.
Ques. What exactly are Cry proteins? Identify the organism that produces it. How has man used this protein to his advantage? (3 marks)
Ans. Cry Protein (crystal protein) is a toxin that is poisonous to some insects and is encoded by the gene cry. As a result, the plants will be more resistant to insects.
- Cry protein is produced by Bacillus thuringiensis.
- To provide resistance against insect larvae, a cry protein producing gene is transferred to the plant.
- Man has created several transgenic crops by introducing bacteria genes into crop plants such as BT cotton and BT corn.
Ques. Identify the genes that make BT cotton plants resistant to bollworm attack. How do such plants develop resistance to bollworm attacks? Explain? (2 marks)
Ans. Cotton bollworm is controlled by the genes cry IAc and cryIIAb. In Bacillus thuringiensis, 'cry genes' code for toxic insecticidal proteins that exist as inactive prototoxins. These proteins confer pest resistance against cotton bollworms and prevent damage when expressed in cotton crops via genetic engineering. When these insects' larvae feed on cotton plant parts, the toxin activates in their gut, lysing their cells and causing death, making them pest resistant.
Ques. Explain how BT cotton is pest resistant? (4 marks)
Ans. Specific BT toxin genes were isolated from this bacterium and incorporated into a variety of crop plants, including cotton, to provide insect and pest resistance. As a result, cotton plants containing BT genes are referred to as BT cotton plants.
- Cotton boll worms are controlled by the BT toxin genes cry IAc and cry II Ab.
- The bacterium's genes are isolated and incorporated into cotton plants.
- In Bacillus thuringiensis, 'cry genes' code for toxic insecticidal proteins that exist as inactive prototoxins.
- These proteins confer pest resistance against cotton bollworms and prevent damage when expressed in cotton crops via genetic engineering.
- When the larvae of these insects consume cotton plant parts, the toxin activates in their gut, lysing their cells and causing death, making them resistant to pests.
Ques. Why do Bacillus thuringiensis' toxic insecticidal proteins kill the insect but not the bacteria? (2 marks)
Ans. Since it exists as an inactive protoxin, BT toxin does not kill bacteria. When an insect consumes BT toxin, the alkaline pH of the gut converts it into its active form. The activated toxin binds to the surface of the midgut epithelial cells, causing pores to form. Water enters the insect body, causing swelling and cell lysis.
Ques. Why is Bacillus thuringiensis thought to be suitable for the development of GM plants? Explain how it was used to create GM crops? (4 marks)
Ans. Bacillus thuringiensis produces a protein that is toxic to insect larvae such as bollworm, budworm, flies, beetles, and so on. The BT Toxin gene has been cloned from bacteria and expressed in plants to provide insect resistance without the use of chemical insecticides.
The following steps are involved in the development of GM plants:
- Using restriction enzymes, a cry gene coding for proteins was isolated.
- They are cloned in vectors and then introduced into crop plants of interest.
- CrylAc and cryllAb are two types of cry genes that code for insect-specific cry proteins that control cotton bollworm.
- Corn borer is controlled by crylAb.
- Transgenic plants, such as BT cotton, BT corn, and BT rice, produce the protein and exhibit insect pest resistance.
Ques. Define plasmid and ADA deficiency? How does gene therapy address this issue? Why isn't there a permanent cure? (3 marks)
Ans. A plasmid is a naturally occurring extrachromosomal, self-replicating, circular, double-stranded DNA molecule found in bacteria. ADA deficiency is caused by the deletion of the adenosine deaminase enzyme gene. This enzyme is essential for human immune system function.
- In gene therapy, lymphocytes from patients' blood are grown in a culture outside the body.
- A functional ADA cDNA is then introduced into the lymphocytes via a retroviral vector.
- After that, the lymphocytes are returned to the patient.
- Since these cells are not immortal, the patient requires infusions of genetically engineered lymphocytes on a regular basis.
Ques. Explain: (A) Which is the first transgenic plant
(B) Who discovered the BT gene? And when was it discovered? (2 marks)
Ans: (A) The first transgenic plant was an antibiotic-resistant tobacco plant produced in 1982.
(B) BT gene was discovered in 1911 by Ernst Berliner.
Ques. List out the disadvantages of BT crops? (2 marks)
Ans. Few disadvantages of BT crops are as followed:
- BT crops are more expensive than naturally grown crops.
- BT crops have the potential to disrupt the natural process of gene flow.
- Pests may develop resistance to the toxins produced by these crops, resulting in decreased crop production.
Ques. What is BT Brinjal? (3 marks)
Ans. The development of BT brinjal also involves the genetic transformation of Bacillus thuringiensis crystal protein gene cry 1 Ac. It was developed to offer protection from lepidopteran insects.
- Proteins produced by BT genes attach to membrane receptors on insects.
- The membranes develop pores as a result of it.
- The insect dies as a result of the digestive system being upset.
- But there has been a lot of discussion over this crop in India.
- BT Brinjal will result in an 80% reduction in the use of pesticides during cultivation.
Ques. What are BT Gene? (2 marks)
Ans. The bacterium Bacillus thuringiensis is a soil-dwelling bacteria that carries the Bt gene. It secretes a poison naturally that kills some herbivorous insects. It has been used as an insecticide spray in organic farming since 1920. It is also the source of the gene that is utilized to genetically alter a variety of crops, enabling them to generate the toxin necessary to eradicate different insect pests on their own.
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