Bioagriculture: Transgenic Plants and Genetically Modified Organisms

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Bio-agriculture Transgenic Plants and
Genetically Modified Organisms

• E124Spring 2005

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Goals of Bio-agriculture

• Increase resistance to pests (e.g. Bt-cotton).
• Raise tolerance to pesticides (e.g.
  Herbicide-tolerant soybean).
• Increase market value.
• Reduce dependence on pesticides.
• Herbicides (e.g. Atrazine)
• Fungicides (e.g. Alachlor, Aldicarb)
• Insecticides (e.g. Lindane, Parathion)

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GMOs in the U.S.

• 75 of the cotton crop.
• 50 of the soy bean crop.
• 20 of the corn crop.
• Other crops (canola, cherry tomatoes, squash,
  sugar beets, potatoes).

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Some GMO Products

• Kelloggs Corn Flakes
• Heinz Baby Cereal
• Nestle Carnation Infant Formula
• Quaker Chewy Granola Bars
• Ultra Slim Fast
• Aunt Jemima Pancake Mix
• Alpo Dry Pet Food
• McDonalds McVeggie Burger
• Old El Paso Taco Shells

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Environmental Ecological Hazards

• The movement of the transgene itself with
  subsequent expression in a different organism or
  species.
• The transgenic plant itself.
• Non-target hazards associated with the transgene
  product outside the plant.
• Resistance evolution in the targeted pest
  population.

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Hazards Associated With Gene Movement

• Seed dispersal due to spillage during travel or
  from the plant itself .
• Horizontal transfer the nonsexual transfer of
  genetic material from from one organism to the
  genome of another.
• Pollen dispersal to other varieties of that crop,
  related crops and wild relatives.

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Hazards Associated With the Whole Plant

• The transgenic plant itself may become an
  environmental hazard because the traits it
  receives may improve its fitness and ecological
  performance.
• The addition of a single transgene that improves
  some ecological characteristic could increase the
  weediness or invasiveness of the species.

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Non-target Hazards

• These are species that are not the direct target
  of the transgenic crop
• Beneficial species, including natural enemys of
  the pests.
• Non-target pests.
• Soil organisms.
• Species of conservation concern.
• Biodiversity, includes species richness.

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Hazards of Resistance Evolution

• Resistance evolution can occur in pests that are
  targeted for control by or associated with a
  transgenic crop.
• Insect resistance to Bt crops is considered
  inevitable.
• Virus resistance has not been used extensively,
  but many viruses have evolved resistance to
  conventional crop resistance.
• Fungal and bacterial resistance is not yet
  commercially available, but have evolved
  resistance within 5 years for conventional
  approaches.
• Herbicide tolerant transgenic crops are designed
  so that weed control is easier, however as weeds
  evolve resistance the benefit is lost.

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Potential Risks to Human Health

• Allergic reactions.
• Compromise human immunity (antibiotic
  resistance).
• Removal of valuable nutritional substances in
  food.

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Ethical Issues

• Cultural shifts in farming due to the
  introduction of terminator seeds.
• The anecdotal evidence of allergies to
  genetically modified crops.
• The lack of an adequate risk assessment
  methodology to quantify unintended ecological
  consequences.
• Resistance of intestinal bacteria to antibiotics.
• The preservation of natural genetic crop-lines.

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Substantially Equivalent

• Some of the ethical dilemmas concerned with GMOs
  are a result of treating genetically modified
  crops as being substantially equivalent to
  conventional crops.
• This has led to issues such as product labeling,
  patents, and regulation.

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Uncertainty theory, in a nut shell

• As we know,
• there are known knowns.
• There are things we know we know.
• We also know
• there are known unknowns.
• That is to say,
• we know there are some things
• we do not know.
• But there are also unknown unknowns,
• the ones we don't know
• we don't know.
• Donald Rumsfeld, U.S. Secretary of Defense
  , Iraq Weapons of Mass Destruction Press
  Conference

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The Precautionary Principle

• 1992 Rio Declaration, Where there are threats
  of serious or irreversible damage, lack of full
  scientific certainty shall not be used as a
  reason for postponing cost-effective measures to
  prevent environmental damage.

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The Precautionary Principle (PP) Vs. Science
Based Risk Assessment (RA)

• Type I errors the probability of erroneously
  rejecting a valid hypothesis (false negative).
• Type II errors the probability of accepting an
  invalid hypothesis (false positive).
• The PP tries to protect against type I errors and
  RA tries to protect against type II errors.