genetically modified organisms - adam oliver...

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BIO 4101: Pesticides and the Environment BIO 4101: Pesticides and the Environment 1

Genetically Modified Organisms


Genetically Modified Organisms

!  Farmers have been genetically modifying plants for 1000s of years

!  Modern technology allows for the insertion of desirable genes into target organism genomes (transgenics)

BIO 4101: Pesticides and the Environment BIO 4101: Pesticides and the Environment

Agriculture and Agri-Food Canada/Canadian Food Inspection Agency

!  There is a continuum – Plant cultivation/animal husbandry – Selective breeding –  Intra-specific gene transfer –  Inter-specific gene transfer

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From Canadian Environmental Protection Act

!  Biotechnology: – The application of science and engineering in

the direct or indirect use of living organisms, or parts or products of living organisms in their natural or modified forms

– Very general, applies to all processes and products from microbes to humans

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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:


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.)


Why Modify Organisms? !  1) Agriculture

–  A) improve food quality/quantity –  B) expand food production –  C) resistance/tolerance to insects –  D) resistance/tolerance to herbicides

!  2) Public Health –  Production of vaccines or protein products (ex. Insulin,

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, microbial pesticides or fertilizers


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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Agricultural Use of GMOs !  Make better plants

–  Traits associated with yield (seed quality, early maturation, nitrogen fixation etc.) or with environmental tolerance (dessication, cold-hardiness etc.) are often multi-gene complexes, therefore molecular techniques are too complicated

!  Pesticide resistance: –  Traits for resistance are often associated with only one gene in

particular !  Pest control

–  Bacillus thuringiensis easy to insert through bacterial cloning (Agrobacterium tumefasciens)


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


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


Concern Over GMOs !  Neoliberal out-sourcing to

private market forced biotech into hands of multi-nationals in 80-90s

!  Public mistrust over incentives of companies for safety over profit

!  Blending of arguments between regulation of food products and scientific potential of biotech

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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?

–  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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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


!  1) Modification of the rhizosphere by gene transfer (lateral transfer common in bacteria)

Potential Risks of GMOs - Environment


!  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 seeds and crops

–  Herbicide resistance not really an issue in nature, other forms of tolerance could be problematic

–  HT plants could re-invade agriculture


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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!

– Contaminate non-target foods •  Monarchs on Asclepiad



!  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.)



!  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


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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.



!  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



!  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


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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


!  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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Target Species

Source: G Frisvold, University of Arizona


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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


!  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



Evaluation of GMO Risks

!  GMO plants must be exactly the same as cousin plant, all respects related to health and safety

!  Must be considered “Substantially Equivalent” – Agricultural, environmental

and public health parameters

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Global Trends in GMO Use

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USDA

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Recent Trends

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Recent Trends

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References

!  Stephenson and Soloman. 2007. Pesticides and the Environment. CNTC Press.

!  Leiss and Powell. Mad Cows and Mother’s Milk. McGill-Queens U Press

!  McHughen, A. 2000. Pandora’s picnic basket. Oxford University Press

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