Post on 23-Jul-2020
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BIO 4101: Pesticides and the Environment BIO 4101: Pesticides and the Environment 1
Genetically Modified Organisms
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Genetically Modified Organisms ! Farmers have been genetically
modifying plants for 1000s of years – Artificial selection propagates bad
traits with the good – Most recently, trying to eliminate
bad traits ! Modern technology allows for
the insertion of desirable genes into target organism genomes (recombinant DNA)
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Why Modify Organisms? ! 1) Agriculture
– A) resistance/tolerance to insects – B) resistance/tolerance to herbicides – C) resistance/tolerance to pathogens
! 2) Public Health – Production of vaccines (ex. insulin) or protein products
(ex. Growth hormones) ! 3) Forestry
– Production of tree varieties resistant/tolerant to pathogens or of increased quality (ex. Lignin production, pollution tolerance)
! 4) Other – Industrial biomaterials, environmental rehabilitation
organisms
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History of GMOs ! First products: bacterial gene insertions to create
human protein products – Insulin – Growth hormones – No societal resistance whatsoever
! First products intended for human consumption:
– Plants resistant to pesticides – GMO tobacco in field studies
from 1986-1989
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History of GMOs ! Pesticide resistance:
– Traits associated with yield (seed quality, early maturation, nitrogen fixation etc.) are often multi-gene complexes, therefore molecular techniques are too complicated
– Traits for resistance are often associated with only one gene in particular
! Bacillus thuringiensis: – Express toxins specific to pests
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Future GMOs ! Nutraceuticals
– Medicinal properties – Functional foods – Added value
! Transgenic animals – Milk with added nutrition/medicines – Less susceptible to disease – Limit pollution from manure – Faster growing, more hardy
! Plants tolerant to wider range of conditions – Dessication, salt, better PS
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Avantages of GMOs
! Increase yield/decrease losses ! Decrease external costs ! Increase value of crops ! Reduce environmental damage ! Improve quality of life by eliminating
deleterious genes (ageing, cancers etc.)
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Concerns over GMOs
! 1) Subjective – Ethical, political, theistic, social,
economic! ! 2) Rational/scientific
– A) poses no danger upon consumption • Ex. Human or animal food
– B) poses no danger to the environment • Ex. Perturb ecological processes • Ex. Resistance
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! Much confusion, ignorance and disinformation exists
! Most people lack the basic understanding required to discuss the topic – Ex. a UK poll demonstrated that 60% of
respondents did not realize that non-GMO tomatoes also contained genes
! Other problem: there is no consensus on the definition of a GMO
Concerns over GMOs
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Non-scientific Concerns ! 1) over the process
– Unnatural, ‘playing God’ – Due to molecular homology we already
share most of our genes across very distant taxa! what’s one more?
– Pork gene in a tomato • Can it be eaten by jews/muslim? • What if the gene already exists in tomatoes?
– For non-food GMOs (insulin or cystic fibrosis enzyme from bacterial gene insertion and cloning) • Most people are ok with this form of GMOs so
they are not inherently against the process itself
! 2) over the products (potential) – Creating ‘monsters’ – Haven’t yet seen any problems
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Genetically Modified Organisms ! Genetic modification = genetic
engineering = recombinant DNA (rDNA) – A series of technologies and processes – Ex. Molecular analysis, gene
identification, gene extraction and cloning, gene splicing and gene transfer
– Most people consider only the latter to be GM
– We end up by creating an organism with novel traits
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Genetically Modified Organisms ! In Canada, a GMO doesn’t exist:
– Organism with Novel Traits: All organisms with traits that do not exist in the natural varieties
– This applies to organisms created by traditional methods of selection
– Most of our food (microbes, plants, animals) are currently genetically different from their natural cousins
http://www.inspection.gc.ca/plants/plants-with-novel-traits/eng/1300137887237/1300137939635
See the Canadian Food Inspection Agency Website:
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National Evaluation of GMOs ! As a function of their inherent
properties – Ex. Canada – Control is based on the product, not the
process ! As a function of their mode of
production – Ex. USA – Process, not the product
! As something completely different – Ex. EU
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Confusion Surrounding Regulation ! Different processes are often
confused with one another – Ex. Herbicide-resistant Canola
coming from Canada (GMO) are banned in the UK, but not those coming from Australia (conventional)
– Ex. Whole organisms and derived products are often considered as equivalent - tomatoes (intact DNA) vs. paste (denatured DNA)
– Some refined products contain no genes or protein products (oils, sugars etc.)
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Conventional Genetic Modification Techniques
! Selection ! Crossings ! Emasculation
– Prevent paternity in non-desirable plants
! Genus crossings – Ex. Triticale: wheat and rye
! Haploid selection – Forcing double haploid embryos to
develop
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! Mutant selection – Expose plants to mutagens to see what is
created – >1400 cultivars from several spp.
! Somaclonal variation – Provoke genetic changes during micro-
propagation in cultures ! Cell selection
– Growth of cultured cells and mutants are selected for propagation
– Selection for resistance is based on applying noxious chemicals or poisons to remove normal cells
Conventional Genetic Modification Techniques
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Potential Risks of GMOs
! Risk: probability that something poses a danger
! To public health: – Increase in toxicity, allergens or
decrease in nutritional quality – Risk for toxicological profile is calculated
using a) biological activity of the product, b) the frequency, intensity and duration of exposure
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! 1) Modification of the rhizosphere by gene transfer
Potential Risks of GMOs - Environment
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! 2) Diffusion of GMOs into the environment – Super-Weeds could become invasive – In W Canada, natural populations of
Canola have become resistant to herbicides
– Margin of security: artificial selection has weakened hardiness of agricultural crops
– Herbicide resistance not really an issue in nature, other forms of tolerance could be problematic
Potential Risks of GMOs - Environment
http://www.cbc.ca/news/business/story/2012/01/12/super-weed-alberta.html
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! 2) Diffusion of GMOs into the environment – Gene flow between GMO populations and
natives – 12/13 of the most important plant crops are
grown in proximity of their wild cousins (ex. wheat, rice, corn, soya, cotton, barley)
– How to control? • Dispersal by pollinators, seeds!
Potential Risks of GMOs - Environment
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! 2) Diffusion of GMOs into the environment – Ex: Starlink Corn (B.t.) – Protein product Cry9C (similar to
many allergens) – Banned from human
consumption – Approved pour industrial non-
food uses, animal feed and the production of grain
– Contamination has been documented in food products (requires recalls, inquiries, compensations etc.)
Potential Risks of GMOs - Environment
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! 3) Risks of insects developing resistance to GMOs – Many species already show B.t.
resistance in laboratory – One case observed in nature:
Diamond-backed moth (Plutella xylostella) on crucifers in FLA and NY
! Selection pressures are more intense because expression is continuous in GMOs
Potential Risks of GMOs - Environment
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! Strategies to reduce the potential for resistance
– Mixed cultures – Non-GMO refugia
around GMO crops – EPA (2000): no more
than 80% of a crop can be GMO B.t.
Potential Risks of GMOs - Environment
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! 4) Negative effects on biodiversity – Agriculture is already among the human activities
that leads to biodiversity losses – UNEP: biodiversity loss has been accelerating
since 1600, has reached 100x the natural rate – A) genetic homogenization of parental stocks – B) effects on non-target organisms and up the
food chain
Potential Risks of GMOs - Environment
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! Pleiotropic effects – Genes rarely act in isolation – Many interactions exist
between genes and the genome • Ex. Regulators of the
expression of other genes (amplitude)
• Ex. Initiators or terminators of the expression of other genes
Potential Risks of GMOs
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! Reduction of pesticide use – Australia: noticed a reduction of 50% in 2 years
with B.t. cotton – USA (1998-1999): reduction of 21% with B.t.
cotton – USA: reduction of 10-30% with GMO soya – USA in general (FDA): pesticides were reduced in
7/12 regions, but not in the other 5/12
Potential Advantages of GMOs - Environment
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! Why no reduction in 5/12 regions? – Herbicide resistant GMOs created to be specifically
used with a particular pesticide – Ex. Monsanto “Round-up Ready” plants can only
be used with glyphosate
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Potential Advantages of GMOs - Environment
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Target Species
Source: G Frisvold, University of Arizona
Potential Advantages of GMOs - Environment
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! Proposed at the Rio Earth Summit in 1992
! Signed at the UN conference on the Environment and Sustainable Development
! “if an action or policy has suspected risk of causing harm to the public or to the environment, in the absence of a scientific consensus that harm would not ensue, the burden of proof falls on those who would advocate taking the action.”
Precautionary Principle
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Cartagena Protocol ! UN convention on biological
diversity in Montréal in 1993 ! Strategies aimed a maintaining biological
species and ecosystem diversity ! Addition to the PP in order to include the
risks associated with biotechnologies (GMOs)
! PP and CP: international guidelines for the evaluation and standardization of food products
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Scrutiny of GMOs ! GMO creation is under rigorous and
elaborate scrutiny at every step – Many more varieties are created by genetic
engineering than by conventional methods
– We have no idea what genes are created by mutation but we know exactly with gene transfer
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! Have been growing experimentally for 35-40 years – Thousands of generations of GMO plants
! GMO products have been consumed by humans since 1994
! No pronounced effect has been observed in public health or on ecosystem functioning to date
! When unintended effects have been discovered, those strains have been scrapped – Ex. Beans with nut gene
Potential Risks of GMOs
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Evaluation of GMO Risks
! GMO plants must be exactly the same as cousin plant, except for GM
! Must be considered “Substantially Equivalent” – Agricultural, environmental
and public health parameters
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Production of GMOs
GMO plants World cultivated surface (M ha) % of all GMOs
% of this plant’s production
globally
Soya 25,8 58,4 36
Corn 10,3 23,3 16
Cotton 5,3 12 11
Canola 2,8 6 7
Total 44,2 99,7 70
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Worldwide use of GMOs (M ha)
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The trend continues!
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GMO use by region in 2000 (# of varieties) USA Canada UK
Corn 12 15 1
Canola 7 15 5
Tomatoes 6 3 4
Cotton 5 5 0
Potatoes 4 4 0
Soya 3 1 1
Beets 2 0 0
Gourds 2 2 0
Radishes 1 0 0
Papaya 1 0 0
Linseed 1 1 0
Total 44 42 11
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Global GMO Use (M ha) Country 1999 2000 % change USA 28,7 30,3 +5,6
Argentina 6,7 10,0 +49,3
Canada 4,0 3,0 -25,0
China 0,3 0,5 +66,7
S Africa 0,1 0,1 +100
Australia 0,1 0,2 +100
Other <0,1 <0,1 -
Total 39,9 44,2 +10,8
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GMO Use in Canada (M tons) Canada Ontario Quebec
Wheat 20 695,3 1 222 116,9
Corn 7 550 4 750 2 800
Barley 11 103,3 387,5 485
Oats 2 838,3 74 210
Rye 201,5 54,6 3,2
Soya 2 040,1 1 660,1 380
Canola 4 788,8 31,3 10
Mixed Cereals 375,8 208,7 3,2
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Production of GMOs in 2000 (M $US)
Sales R&D Syngenta (Swiss) 5 888 745
Monsanto (USA) 3 885 588
Aventis (France) 3 701 469
DuPont (USA) 2 511 1776
Dow (USA) 2 271 892
Bayer (Germany) 2 252 2208
BASF (Germany) 2 228 758
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References
! Gouvernement du Québec. Conseil de la science et de la technologie. 2002. OGM et alimentation humaine: impactes et enjeux pour le Québec. 178p.
! McHughen, A. 2000. Pandora’s picnic basket. Oxford University Press, NY. 277p.