Bt cotton


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Bt cotton

  1. 1. Technology of Bt cotton Ditipriya Hazra 13BT60R18
  2. 2. What is Bt cotton ? •Genetically modified variety of cotton that produces an insecticide. •Marketed by Monsanto, USA.
  3. 3. 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.
  4. 4. Structure of Cry protein Domain I •7 α-helix •Helps in membrane insertion Domain II • β-prism of 3 antiparallel β- sheets •Helps in receptor recognition Domain III • β-sandwich of antiparallel β - sheeets Crystal structure of Cry protein
  5. 5. Timeline 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 parasporal crystal 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
  6. 6. 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)
  7. 7. Objective •To understand the general mode of action of Cry toxin •To understand the technology behind Bt cotton production. •To comprehend the current scenario of Bt cotton in India.
  8. 8. How Bt works ? 1. Ingestion 2. Solublization & proteolytic activation 3. Binding to target site 4. Formation of toxic lesions
  9. 9. Mode of action of Cry toxin
  10. 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. 11. Methods of gene transfer •Agrobacterium mediated gene transfer •Bombardment of cells with particle coated with gene of interest Two routes of gene transfer
  12. 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 Bacterial chromosomeTi Plasmid Petri dish with leaf pieces & Agrobacterium
  13. 13. Agrobacterium mediated gene transfer
  14. 14. 14 ‘Particle Gun’ DNA coated on pellets is forced down the barrel of a ‘Particle Gun’ by an explosive charge The particles are forced through the cell wall where the DNA is released Barrel Explosive Charge Vent Stop plate Petri Dish with cultures Projectile DNA coated pellets
  15. 15. Production of Bollgard® •Agrobacterium mediated transfer • CaMV35S promoter •Somatic embryogenesis.
  16. 16. Advantages of Bt-cotton •Yield superiority •More profit •Lesser need of pesticide •Better quality •Suitability for early sowing
  17. 17. Disadvantages •Higher cost of seeds •Higher fertilizer and irrigation cost •Higher harvest cost
  18. 18. 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.
  19. 19. •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.
  20. 20. 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
  21. 21. 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.
  22. 22. Reference • 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. 193-222. • 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