This document discusses Bacillus thuringiensis (Bt), a soil bacterium that produces crystal proteins toxic to certain insect pests. It introduces Bt cotton, Bt brinjal, and Bt corn, which have been genetically engineered to produce these Bt crystal proteins, providing resistance against key insect pests like the cotton bollworm and brinjal fruit and shoot borer. The document discusses the mechanisms through which Bt proteins act selectively on insect pests while being safe for humans and other organisms. It also outlines the process of developing transgenic crops and highlights advantages like reduced pesticide use and increased yields.

2. MANOJ B.S
15MSABC005
M,Sc. AGRI BIOCHEMISTRY.
JSBB. SHIATS,ALLAHABAD.
SAM HIGGINBOTTOM INSTITUTE OF
AGRICULTURE, TECHNOLOGY AND SCIENCES

3. CONTENT
 INTRODUCTION ABOUT Bt.
 Bt. COTTON
 WORKING MECHANISM OF Bt.
 ADVANTAGES AND DISADVANTAGES OF Bt. COTTON
 Bt. BRINJAL AND ITS PRODUCTION TECHNIQUES
 ADVANTAGES AND DISADVANTAGES OF Bt. BRINJAL
 Bt. CORN AND ITS BENEFITS.

4. Shigetane Ishiwatari (1901), first isolated Bacillus
thuringiensis.
Bt is commonly abbreviated as Bacillus thuringiensis,
is a gram-positive, facultative aerobic, rod-like,
motile and sporulating bacterium.
Bt is a naturally-occurring soil borne bacterium that
is found worldwide
Ubiquitous in nature.
Produces crystals of endotoxin (Cry protien or delta
toxin) - toxic to insect mainly in their larval stage,
thus they act as insecticides.
Bacillus thuringiensis

5. These crystal proteins (Cry proteins) are insect
stomach poisons
Insects stop feeding within two hours of a first
bite and, if enough toxin is eaten, die within two
or three days
Important biological insect control agent.
Bt crystals, sometimes referred as insecticidal crystal
proteins (ICP), are protein crystals formed during
sporulation in some Bt strains coded by cry genes.

6. What is Bt cotton ?
• Genetically modified variety of cotton
that produces an insecticide.
• Marketed by Monsanto, USA.

7. HOW Bt WORKS ?
1. Ingestion
2. Solublization & proteolytic activation
3. Binding to target site
4. Formation of toxic lesions

8. Mode of action of Cry toxin

9. Epithelium
Dissolving of crystals and
activation of toxins
Pro-toxin
Activated ∂- endotoxin
Receptors
Toxins bind to receptors
Perforation of
gut membrane
Crystals
Hilbeck and Schmidt
(2006)
Fig 10: Mode of Action of Bt Toxin in Insect Gut

10. TECHNOLOGY OF PRODUCTION
• Main steps for developing transgenic crops :
1. Identification of effective gene(s).
2. Gene transfer
3. Regeneration from protoplast/callus/tissue
4. Gene expression to the desired level
5. Back cross to produce varieties
6. Field test
7. Approval for commercialization

11. METHODS OF GENE TRANSFER
• Agrobacterium mediated gene
transfer
• Bombardment of cells with
particle coated with gene of
interest

12. Transformation with Agrobacterium
• Agrobacterium contains a circle
of DNA (Ti plasmid) that carries
the desired genes
• Co-cultivation of the
Agrobacterium with plant pieces
transfers the DNA
Petri dish with leaf pieces & Agrobacterium

13. Bt cotton in India
• India is the largest cotton producer and consumer country
after China.
• In 2002 Bt cotton was introduced in India.
• India has the largest hectarage of cotton and accounts for
approximately one third of the total cotton are planted in
the world.
• Cotton yield increased from 308kg/ha in 2001-02 to
550kg/ha in 2014-15.

14. Advantages of Bt-cotton
• Yield superiority
• More profit
• Lesser need of pesticide
• Better quality
• Suitability for early sowing

15. DISADVANTAGES
• Higher cost of seeds
• Higher fertilizer and irrigation cost

16. Trade name Bt protein crop Company Insect pests
Bollgard Cry1Ac Cotton Monsanto Tobacco budworm,
cotton bollworm,
pink bollworm
Bollgard II Cry1Ac+Cry2Ab Cotton Monsanto Tobacco budworm,
cotton bollworm,
pink bollworm
Widestrike Cry1Ac+Cry1Fa cotton Dow Tobacco budworm,
cotton bollworm,
pink bollworm
List of transgenic cotton (Bt cotton)

17. Commercial release of different Bt cotton events in India, 2002
to 2009
No. Event Developer Status Date of approval
1 MON-531 Mahyco/Monsanto commercialized 2002
2 MON-15985 Mahyco/Monsanto commercialized 2006
3 Event-1 JK Agri-Genetics commercialized 2006
4 GFM Event Nath Seeds commercialized 2006
5 BNLA-601 CICR (ICAR) & UAS,
Dharwad
commercialized 2008
6 MLS-9124 Metahelix Life Sciences commercialized 2009

18. Future prospects of Bt cotton in India
• 5 new hybrid cottons are under biosafety assessment which will
be considered for commercial approval between 2013-15.
• . Other traits include drought and salinity tolerance, disease
resistance, sucking insect resistance, leaf curl virus resistance
and other traits related to cotton fiber quality.

19. Bt. BRINJAL
Brinjal is botanically known as Solanum melongena L. (2n =24) included under the genus Solanum
which is one of the largest genera having more than 1,500 described plant species.
The cultivated types are fit for human consumption and are divided into three main varieties based
on fruit shape.
S. melongena var. esculentum
(Round or egg-shape)
S. melongena var. serpentinum
(Long and slender)
S. melongena var. depressum
(dwarf brinjal plants)

20. MAJOR PROBLEMS
• Major problem in brinjal cultivation is brinjal shoot and
fruit borer (Leucinodes orbonalis).
• It is monophagous and attacks all aerial parts of plant
specially shoot and fruit.
• Damage the fruit and affect fruit quality badly.
• It causes yield losses about 60-70% even after multiple
insecticide spray.

21. EGGS
LARVAE
PUPAE
ADULT
25-43 days
Fig 6: Life Cycle of The Fruit and Shoot Borer

22. SHOOT DAMAGE FRUIT DAMAGE
Symptoms of Damage

23. Bt Brinjal is a transgenic brinjal created out of inserting a gene [cry IAc] from the
soil bacterium Bacillus thuringiensis in to brinjal.
The insertion of the gene into the Brinjal cell in young cotyledons has been done
through an Agrobacterium mediated vector, along with promoters, markers etc.
This is said to give the Brinjal plant resistance against lepidopteran insects like the
Brinjal Fruit and Shoot Borer (Leucinodes orbonalis) and Fruit Borer (Helicoverpa
armigera).
It is reported that upon ingestion of the Bt toxin by the insect, there would be
disruption of digestive processes, ultimately resulting in the death of the insect.

27. 1 INOCULATION
2 CO-CULTIVATION
3
4
5
6
SELECTION & REGENERATION
RE-GROWTH
MOLECULAR VERIFICATION OF GENE
PRESENCE & EXPRESSION
EVALUATION OF TRANSFORMED BRINJAL
PLANT FOR INSECT PROTECTION

28. • 60% of plant protection cost for controlling fruit and shoot borer is
reduced.
• In spite of the extensive use of chemical pesticides, larvae lead a
concealed life, it is difficult to control through insecticide sprays.
Arguments in Favour of Bt Brinjal

29. WHAT ARE THE BENEFITS OF Bt BRINJAL.?
1) non-infested, undamaged and good quality brinjal fruits.
2) Bt brinjal will significantly reduced level of pesticide residues,
Farmers are expected to benefit at multiple levels. Some of these include:
3) Saving on cost of insecticides and lower labor cost as a result of reduced
spraying.
4) Increase in yield per unit area by saving fruits from damage caused by FSB.

30. Non-Bt. Non-Bt.
Benefits to Farmers
Bt.

31. Bt. CORN
Why does corn need protection from corn
borers?
Each year, 40 million tons of corn never reach the
market due to damage.
If corn borers are not controlled, the larvae will
eventually turn into moths and the cycle continues.
Bt corn produces a protein that gives Bt corn built-
in resistance to the corn borer – offering protection
throughout the plant where the insect attacks.

32. HOW DOES Bt. CORN WORK?
Bt maize has built-in protection against corn borers, achieved through
modern biotechnology, where the Cry1Ab gene has been added.
The Cry1Ab gene produces a Bt protein (Cry1Ab) which protects the plant
from insect damage (Bacillus thuringiensis )
Stalk tunnel after infectionTunneling of borer

34. What are the benefits of Bt corn?
It represents an environmentally sustainable way
to control devastating insect pests and, therefore,
to ensure yield.
Also, grain from Bt corn is often of better quality
than grain from conventional corn hybrids, since
insect damage reduces grain quality.
Studies show that there is a significant economic
return from growing Bt corn, with yields protected
in years when there is a heavy outbreak of corn
borer.
There is also evidence that Bt corn provides a
form of protection to non-Bt corn by reducing the
overall population of corn borers

35. Expected benefits are based on the following
assumptions
• Bt corn (MON810, BT11) provides 96% average control
of European corn borer larvae,
• Bt corn (event 176) provides 96% control of first
generation corn borers and 75% control of second
generation corn borers.
• Insecticides provide 80% and 67% control of first and
second generation borers, respectively.

36. Does Bt corn affect beneficial insects and natural
enemies?
 Many studies have shown that Bt Cry proteins are highly selective in
killing larvae of moths.
 Bt corn, however, does not affect beneficial insects including honey bees,
lady beetles, green lacewing larvae, spiders, pirate bugs or parasitic
wasps .
 Indirect effects on natural enemies of European corn borer, however,
could occur.
 Predators, parasites and pathogens of the corn borer might decline as
corn borer populations decline.

37. 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

38. 1Hilbeck and Schmidt (2006).
2. Anonymous, 2009
3. Choudhary & Gaur, 2009
4. Bravo A., Gill S. S., & Soberon M. (2007). Mode of action
of Bacillus thuringiensis Cry and Cyt toxins and their potential
for insect control. Toxicon, 49(4), 423-435
5. Aronson, A. (2002). Sporulation and δ-endotoxin synthesis
by Bacillus thuringiensis. Cellular and Molecular Life
Sciences CMLS, 59(3), 417-425.