The document discusses Bt crops, which are genetically engineered crops containing genes from the soil bacterium Bacillus thuringiensis. These genes allow the crops to produce Bt toxins that are insecticidal against certain pest insects. Some examples of Bt crops mentioned include cotton, brinjal, and corn. The document also discusses the bacterium B. thuringiensis, how it produces cry proteins toxic to insects, and how genes from it were introduced into plants starting in 1996. Advantages of Bt crops include increased yields and reduced need for pesticides, while disadvantages include higher costs and potential for pests to develop resistance over time.

1. The Concepts and
Development of BT
Crops

2. What are Bt Crops?
• Bt crops are transgenic crops that are genetically
engineered from the DNA of bacterium Bacillus
thuringiensis.”
• Bt Crops are transgenic crops that produce the
same toxin as the bacterium Bacillus
thuringiensis in the plant cell, thereby, protecting
the crops from pests. The bacterium secretes
specific proteins known as “cry proteins” that are
toxic to insects. A few of the Bt crops include
cotton, brinjal, corn, etc.

3. Bacillus thuringiensis
• Bacillus thuringiensis is a gram-positive, spore-forming bacteria
which is mainly found in the soil. As stated above, it produces
proteins that are toxic to insects. Organic farmers use this bacterium
in a solution and spray it on the plants to protect them from pests.
• The practice of using Bacillus thuringiensis began in the year 1996
with small quantities of genes from the bacterium. This facilitated the
production of cry proteins in plant cells that helped to kill pests. Pests
like European and southwestern corn borer, tobacco and cotton
budworm, pink bollworm and Colorado potato beetle largely
destroyed the crop yields.

5. • Bt Cotton
• Bt Brinjal
• Bt Corn
• Bt Potato
Example of BT Crops

6. Bt Cotton
The Bt cotton variety is genetically
transformed with the Bt gene to protect the
plants from bollworm, a major pest of cotton.
The worms present on the leaves of Bt cotton
become lethargic and sleepy and thus, cause
less damage to the plants. When the worms
consume the plant, the toxic proteins
produced by the crops are ingested, thereby,
killing them.

7. Bt brinjal is also produced by genetic
transformation of a crystal protein
gene cry 1 Ac from the
bacterium Bacillus thuringiensis. Bt
brinjal was developed to provide
resistance against lepidopteron insects.
The proteins produced by Bt genes bind
to the receptors present on the insect’s
membrane, resulting in the formation of
pores on the membranes. This disrupts
the digestive process and leads to the
death of the insect.
Bt Brinjal

8. Bt-Corn
Bt-corn is a type of genetically
modified organism, termed GMO. A
GMO is a plant or animal that has
been genetically modified through
the addition of a small amount of
genetic material from other
organisms through molecular
techniques.

9. Bt corn is a genetically modified organism,
which means a small amount of genetic
material from a different, naturally occurring
organism was added to its genetic makeup.
The modified gene can control a pest or a
group of pests, thus preventing potentially
significant yield losses. One of the most
common pests Bt corn protects against is the
European corn borer.

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Flavr Savr Tomato

11.  Flavr Savr Tomato (also known as CGN-
89564-2) is a genetically modified tomato
with slow ripening and improved shelf
life,produced by Calgene Company,
California(1992).
 It is the first commercially grown
genetically engineered food to be granted a
license for human consumption.
FLAVR SAVR TOMATO

12. Fruit softening is promoted by an enzyme
Polygalactouronase(PG).
It degrades pectin
In the transgenic Flvr Savr Tomato,the
gene that synthesizes Polygalactouronase is
blocked and thus prevented it from softening,
while still allowing the tomato to retain its
natural colour and flavour.

13.  The transgenic variety ripens
normally but experiences less pectin
breakdown and, therefore, has
increased thickness and consistency
that benefits all stages of harvesting
and processing.

14. Advantages of Bt Crops
Following are the major advantages of Bt crops:
• It helps in improving the crop yield, thereby, raising the
farmer’s income. This results in increased farm production.
• They help in controlling soil pollution as the use of synthetic
pesticides is reduced.
• Bt crops help in protecting beneficial insects.
• It can easily feed an increasing population due to increased
yields in a short time.
• It leads to the production of disease-free crops owing to the
reduction of pesticides.
• It leads to more productivity in a small area of land.

15. Disadvantages of Bt Crops
Bt crops have a few disadvantages as well:
• Bt crops are costlier than naturally grown crops.
• It can disrupt the natural process of gene flow.
• The pests might become resistant to the toxins produced
by these crops and the crop production might decline.ke
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16. Bt has no toxic impact in higher animals
(HUMAN) because of…..
• Acidic stomach
• Very low pH (∽1.5 in humans)
• Absence of required receptors
Bt is safe to non-target organisms-
HUMAN