Technology of Bt cotton
What is Bt cotton ?
•Genetically modified variety of cotton that
produces an insecticide.
•Marketed by Monsanto, USA.
What is Bt ?
•Bacillus thuringiensis discovered by
Ishiwatari in 1901.
•Bacterium produces insecticidal crystal
protein (ICP) also known as Cry protein
•They are a class of endotoxin – δ endotoxins.
Structure of Cry protein
Domain I •7 α-helix
•Helps in membrane insertion
Domain II • β-prism of 3 antiparallel β-
•Helps in receptor recognition
• β-sandwich of antiparallel β -
Crystal structure of Cry protein
1901 Shigetane Ishiwatari first isolated the bacterium Bacillus thuringiensis as
the cause of the sotto disease
1915 Berliner reported the existance of a crystal within Bt, but the activity of
this crystal was not discovered until much later
1956 Researchers Hannay, Fitz-James and Angus found that the main
insecticidal activity against lepidoteran (moth) insects was due to the
1958 In the US, Bt was used commercially
1961 Bt was registerd as a pesticide to the EPA
1996 Bt cotton was introduced into US agriculture
Trade name Bt protein crop Company Insect pests
Bollgard Cry1Ac Cotton Monsanto Tobacco
Bollgard II Cry1Ac+Cry2Ab Cotton Monsanto Tobacco
Widestrike Cry1Ac+Cry1Fa cotton Dow Tobacco
List of transgenic cotton (Bt cotton)
•To understand the general mode of action of
•To understand the technology behind Bt
•To comprehend the current scenario of Bt
cotton in India.
How Bt works ?
2. Solublization & proteolytic activation
3. Binding to target site
4. Formation of toxic lesions
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
Methods of gene transfer
cells with particle
coated with gene of
Two routes of gene transfer
Transformation with Agrobacterium
contains a circle of
DNA (Ti plasmid)
that carries the
Co-cultivation of the
transfers the DNA
Petri dish with leaf pieces & Agrobacterium
DNA coated on pellets is
forced down the barrel
of a ‘Particle Gun’ by an
The particles are forced
through the cell wall
where the DNA is
Production of Bollgard®
•Agrobacterium mediated transfer
• CaMV35S promoter
Advantages of Bt-cotton
•Lesser need of pesticide
•Suitability for early sowing
•Higher cost of seeds
•Higher fertilizer and irrigation cost
•Higher harvest cost
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.
•For 11th year Bt cotton was planted in India in
10.8 mil hectares .
•Decline in insecticide use was from US$160
million in 2004 to US$25 million in 2010 –
an 85% decrease
•Cotton yield increased from 308kg/ha in
2001-02 to 500kg/ha in 2011-12.
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,
6 MLS-9124 Metahelix Life Sciences commercialized 2009
Future prospects of Bt cotton in
•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.
• Aronson, A. (2002). Sporulation and δ-endotoxin synthesis by Bacillus thuringiensis. Cellular and Molecular Life
Sciences CMLS, 59(3), 417-425.
• 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.
• Dulmage, H.T. (1981) Insecticidal activity of isolates of Bacillus thuringiensis and their potential for pest control.
In Microbial Control of Pests and Plant Diseases 1970-80 (Burgess, H.D., ed.). New York, NY: Academic Press, pp.
• English, L. and Slatin, S.L. (1992) Mode of action of deltaendotoxin from Bacillus thuringiensis: a comparison with
other bacterial toxins. Insect Biochem. Molec. Biol. 22, 1-7.
• Perlak, F.J., Deaton, R.W., Armstrong, T.A., Fuchs, R.L., Sims, S.R., Greenplate, J.T. and Fischhoff, D.A. (1990)
Insect resistant cotton plants. Bio/Technol. 8, 939-943