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Bt brinjal
- 3. RISK TO HUMAN HEALTH •Risk of toxicity •Risk of allergies •Antibiotic resistance •Eating foreign DNA •Changes in nutritional level
- 4. Bt Technology •The use of Bacillus thurigiensis to control insect-pests is not new •What is new in Bt crops is that a modified version of the bacterial Cry gene has been incorporated into the plant's own DNA •Plant's cellular machinery produces the delta-endotoxin, as part of the plant's normal development.
- 5. INSECTICIDAL CRYSTAL PROTEINS PRODUCED BY INDIVIDUAL Bacillus thuringiensis STRAINS Bt strain Crystal protein kurstaki Cry1, Cry2, Cry11 aizawai Cry1, Cry9, Cry39, Cry40 entomocidus Cry1, Cry11 galleriae Cry1, Cry7, Cry8, Cry9 israelensis Cry10, Cry11 japonensis Cry8, Cry9 jegathesan Cry11, Cry19, Cry24, Cry25 kenyae Cry1, Cry2 kumamotoensis Cry7, Cry8 morrisoni Cry1, Cry3 tanebrionis Cry3 Tolworthi Cry3, Cry9 wuhanensis Cry1 Slater et al. (2003) Bacillus thuringienesis-A naturally occurring, Gram-positive soil bacterium Genetic engineering of crops with Bt gene(s)has now revolutionized the application of Bt for insect- pest management
- 6. Bt CRYSTAL PROTEIN GENE FAMILY Cry GENE FAMILIES PROTEIN SIZE (kDa) SUSCEPTIBLE INSECT PEST Cry1(A-K) 81-140 Lepidoptera Cry2A 70-71 Lepidoptera Cry3(A-C) 73-75 Coleoptera Cry4(A-B) 128-135 Diptera Cry5(A-B) 135-152 Nematodes Cry6(A-B) 44-53 Nematodes Cry7A 127 Coleoptera Cry8(A-D) 128-130 Coleoptera Cry9(A-D) 130-132 Lepidoptera Cry10A 78 Diptera Cry11(A-B) 72-81 Diptera Cry12-40 Various Various Slater et al. (2003)
- 7. Action of Bt on caterpillars 1) Caterpillar consumes foliage treated with Bt 2) Within minutes, toxin binds to specific receptors in the gut wall, and caterpillar stops feeding 3) Within hours, gut wall breaks down, allowing Bt spores and normal gut bacteria to enter the body cavity; the toxin dissolves 4) Within couple of days, the caterpillar dies as spores proliferate in its blood 1 2 3 4
- 8. Will insects become resistant to Bt toxins? • Bt has been used as a biological insecticide for over 30 years as a spray and there has been little opportunity for insects to evolve resistance • Plants containing a single insect resistance transgene planted commercially by growers • Bt ICPs will be produced continually in plant tissue • Creation of strong selection pressure on both economically important and unimportant insects • If genes conferring resistance to Bt become fixed in insect populations, both sprays and transgenic plants would become ineffective as insect control agents
- 9. Is Bt safe for humans • Toxicity vs allergic reaction • Agencies responsible for the regulation of transgenic plants in the U.S., ie. USDA, APHIS, EPA, FDA. Bt Registration Action Document EPA's review @ www.epa.gov/scipoly/sap: Human health assessment, environmental assessment, outcrossing, non-target species, fate in soils and indirect effects on soil organisms, pollen toxicity, shedding and movement. • Products derived from Bt cotton, corn and potatoes are safe for human and animal consumption (USEPA Biopesticide Safety Sheets; Betz et al., 2000)
- 10. RISK TO ENVIRONMENT • Persistence of transgene/transgene product • Interaction with nontarget organisms • Unprerdictable gene expression or transgene instability • Gene flow • Resistance/tolerance of target pests • Increased weediness • Loss of biodiversity • Changes in soil ecology • Generation of new viruses
- 11. Damage to environment • Crop to weed gene flow • Antibiotic resistance to soil micro-organisms • Leakage of GM proteins into soil
- 13. Regulatory frame work in India 1. Recombinant DNA Advisory Committee (RDAC) 2. Review Committee on Genetic Manipulation (RCGM) 3. Genetic Engineering Approval Committee (GEAC) 4. Institutional Biosafety Committee (IBSC) 5. State Biosafety Coordination Committee ( SBCC) 6. District Level Committees (DLC)
- 14. ...IBSC approval with a copy to RCGM... A. Greenhouse : IBSC approval with a copy to RCGM B. Event selection trial in field – RCGM approval Gene Discovery Cloning Construct Transformation INDIAN REGULATORY SYSTEM FOR DEVELOPMENT AND RELEASE OF TRANSGENIC CROPS Number of Events
- 15. RCGM BRL-1 Field trial:– with a permission from RCGM plus biosafety dossier (Protein thermal stability, pepsin digestibility, acute oral safety limit study, pollen flow study, agronomic evaluation)– To be approved by RCGM. GEAC BRL-11 – Field trial : With permission from GEAC plus subchronic feeding study in rodents + livestock feeding study (optional). Commercialization : Full dossier.