biosafety of gm crops
TRANSCRIPT
Biosafety of Genetically Modified Crops Biosafety of Genetically Modified Crops
Ekatpure Sachin Chandrakant
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Biosafety of GM Crops
Policies and procedure adopted to ensure environmental safety during the course of development and
commercialization of genetically modified organism
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Safety assessment approach for GM crops
335
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Elements of assessment
436
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Regulatory framework in India
537
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Risk of toxicity/ allergineicity
Addition of new genetic material may activate toxic pathways
Appearance of novel metabolites
Introduction of new protein
Non immunogenic protein could become immunogenic
6(Kaeppler, 2000)
Brazil nut allergy in soybean
A well-known case of a GM soybean allergy
2S albumin gene from Brazil nut to soybean (enhanced methionine)
(Julie et al,1996)
Allergen transferred unintentionally from Brazil nut to GM soybean
Investigations with GM soybean revealed immune reactions in people with Brazil nut allergies
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Antibiotic resistance
Marker gene could induce antibiotic resistance Would reduce effectiveness of antibiotics to fight diseases
Conditions for HGT (horizontal gene transfer) : DNA must be free from the cells Bacterial recipient must be competent Integration depends on sequence homology Acid environment of human stomach HGT of nptII gene can occur 1 in 10 billion Specificity of promoter
8(Redenbaugh et al,1994)
Eating of foreign DNA
DNA present in all living things and eaten by humans with every meal
Broken down during digestion process
Small amount absorbed in blood stream or excreted
According to WHO amount of DNA ingested- 0.1 to 1 g/day (novel DNA represents 0.0001%)
(Chawla , 2009) 9
Use of promoters of virus origin
Concerns expressed regarding human health
eg. 35S promoter of CaMV
It might be harmful if it invades human cells and turns on certain genes
Probability is very low and no such report so far
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Changes in nutrition level
Accidental changes in nutritional component of GM crop
Report spread in 1997 that Roundup Ready soybean produces large quantities of phytoestrogen (causes breast cancer) after glyphosate spray
Investigation revealed no such increase
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(SAG report, 1997)
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Gene Flow
Accidental cross between GM plant and traditional local varieties or weedy relative
Contaminate local variety with transgene (eg.superweeds)
Ryegrass highly resistant to glyphosate already found in Austrailia
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(Gaur et al.,2010)
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Report on corn contaminated by GM genes in Mexico
David Quist and Ignacio Chapela in Nov 2001 reported transgenic DNA construct 35s promoter sequence found in Creole maize at Oaxacan state of Mexico
CIMMYT amplified 28 accessions from Oaxacan landraces with CaMV 35s promoter primer
Samples did not show presence of 35s promoter
13(CIMMYT report,2001)
Strategies to prevent gene flow
Isolation zone
Trap crop
Male sterility
Chloroplast transformation
Clean gene technology
- Devoid of vegetation
- Use of non-transgenic variety
- Inactive pollens
- Gene construct introduced into chloroplast
- Markerless GM14(Chawla,2009)
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Resistance of target species
Insect/ virus population rapidly adapt to environmental pressure
Development of new strains
Gene pyramiding - Best solution
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Impact on biodiversity
Reduction in genetic diversity by development and global spread of improved varieties
Sustainable agriculture depends on mixed cropping and crop rotation
Not unique to GM but is relevant to all improved varieties
Bt protein is highly unstable rapidly degraded in stomach juices of vertebrates and in soil
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Monarch butterfly incidence
Monarch butterfly catterpillers died when fed on Bt maize pollen
It was a lab experiment Butterfly fed only on Bt maize pollen For toxic effect of Bt protein it should meet specific dose
requirement In nature it is not possible to meet that dose level
17(Losey et al,1999)
Warangal Attempt
Farmers of Warangal district of Andhra Pradesh reported cattle and sheep dying on consuming Bt cotton plants
No one has so far conclusively proved that Bt protein in the Bt cotton plants was the real culprit
Why do the cattle die eating Bt cotton only in the Telngana region of Andhra Pradesh ?
Clearly a mischievous and cheap attempt to denigrate and discredit the Bt technology
(Rao, 2007)58
Ethical issues
Unacceptable intervention in “God’s creation violating barriers in natural world”
Objections to consuming animal genes in plants and vice-versa
Demand for GM and Non GM food labelling
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