The Science of Transgenics

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The Science of Transgenics
The Sociological, Economic, and Ethical Impact of
Transgenic Organisms Workshop Fargo,
ND February 21, 2003
Phil McClean Department of Plant Science North
Dakota State University
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Transgenics are a Biotechnology Product
How about some definitions
Biotechnology - General Definition
The application of technology to improve a
biological organism
Biotechnology - Detailed Definition
The application of the technology to improve
the biological function of an organism by
adding genes from another organisms
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What About the Term Genetic Engineering?
Genetic engineering is the basic tool set of
biotechnology
Genetic engineering involves

• Isolating genes
• Modifying genes so they function better
• Preparing genes to be inserted into a new
  species
• Developing transgenes

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What is a transgenic?
Concept Based on the Term Transgene
Transgene the genetically engineered gene added
to a species
Ex. modified EPSP synthase gene (encodes a
protein that functions even when plant is treated
with Roundup)
Transgenic an organism containing a transgene
introduced by technological (not breeding)
methods
Ex. Roundup Ready Crops
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Why are transgenics important?
We can develop organisms that express a novel
trait not normally found in the species
Extended shelf-life tomato (Flavr-Savr)
Herbicide resistant soybean (Roundup Ready)
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Agriculture Transgenics On the Market

• Insect resistant cotton Bt toxin kills the
• cotton boll worm
• transgene Bt protein

Source USDA

• Insect resistant corn Bt toxin kills the
• European corn borer
• transgene Bt protein

Normal
Transgenic
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• Herbicide resistant crops
• Now soybean, corn, canola
• Coming sugarbeet, lettuce, strawberry
• alfalfa, potato, wheat (2005?)
• transgene modified EPSP synthase or
• phosphinothricin-N-acetyltransferase

Source Monsanto

• Virus resistance - papya resistant to
• papaya ringspot virus
• transgene virus coat protein

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• Biotech chymosin the enzyme used
• to curdle milk products
• transgene genetically engineered enzyme

Source Chr. Hansen

• bST bovin somatotropin used to increase
• milk production
• transgene genetically engineered enzyme

Source Rent Mother Nature
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Some Ag Biotech Products Are Discontinued
Why???

• Poor Quality
• FlavrSavr tomatoes (Calgene)
• Negative Consumer Response
• Tomato paste (Zeneca)
• Negative Corporate Response
• NewLeaf (Monsanto)
• Universal Negative Publicity
• StarLink corn (Aventis)

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Next Generation of Ag Biotech Products
Golden Rice increased Vitamin A content (but
not without controversy) transgene three
pathway enzymes
Sunflower white mold resistance transgene
oxalate oxidase from wheat
Source Minnesota Microscopy Society
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Turfgrass herbicide resistance slower
growing ( reduced mowing)
Bio Steel spider silk expressed in goats used
to make soft-body bullet proof vests (Nexia)
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Biotechnology is Not Just on the Farm
Disease Treatment Diagnostics   Environmental
Cleanup   Human Applications
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Human Applications

• Pharmaceutical products
• New solutions to old problems
•  
• Disease diagnosis
• Determine what disease you have or may get 
• Gene therapy
• Correcting disease by introducing a
  corrective gene

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Biotechnology and Health
Product Use
Insulin Diabetes
Interferon Cancer
Interleukin Cancer
Human growth hormone Dwarfism
Neuroactive proteins Pain
The genes for these proteins are

• Cloned
• Inserted into bacteria
• Product isolated using biofermentation

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Environmental Applications
Bioremediation - cleanup contaminated sites
uses microbes designed to degrade the pollution
Indicator bacteria contamination can be
detected in the environment
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Future Health-related Biotech Products
Vaccines herpes, hepatitis C, AIDS, malaria
Tooth decay engineered Streptococcus mutans,
the bacteria that destroys enamel
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Edible Vaccines Transgenic Plants Serving Human
Health Needs

• Works like any vaccine
• A transgenic plant with a pathogen protein gene
  is developed
• Potato, banana, and tomato are targets
• Humans eat the plant
• The body produces antibodies against pathogen
  protein
• Humans are immunized against the pathogen
• Examples
• Diarrhea
• Hepatitis B
• Measles

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A Popular Term We Need To Know
GMOs - Genetically modified organisms

• GMO - an organism that expresses traits that
  result
• from the introduction of foreign DNA
• Originally a term equivalent to transgenic
  organism

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The GMO Ruse

• Some claim any improved biological product is a
  GMO

• They feel this will

• ease the publics fear
• pave the way for product acceptance

• For example, some call plant varieties
  biotechnology products

• This is a false claim

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Lets Be Up Front

• Biotechnology adds traits not available in the
  species
•  Soybean does not have a gene to breakdown
  Roundup
• The gene comes from bacteria
• Breeding ? Biotechnology
•  Breeding only exchanges genes found in the
  species
• Breeding can transfer the transgene to other
  breeding materials
•  BUT this does not make it a biotechnology
  procedure

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Important Plant Improvement Methods

• Breeding
• Crossing two individuals from the same
  species
• produces a new, improved variety
• not a biotechnology procedure

Source USDA

• Transformation
• Adding a gene from another species the
• essential biotechnology procedure to produce
• transgenics

Source USDA
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Interspecific Cross
Wheat
Rye
X
Triticale
New species, but NOT biotechnology
products
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Mutagenesis

• A useful procedure to produce a new trait
• But the normal gene is modified
• A transgene is not involved
• The product of mutagenesis is not a GMO

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Mutagenesis Changes the DNA Sequence
Mutagenesis Treatment
Susceptible Normal Gene
ATTCGA
Resistant Mutant Gene
ATTGGA
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BASF Clearfield Products

• Herbicide resistance
• imidazolinones
• Mutant AHAS enzyme
• developed by mutagenesis
• Crops
• Canola
• Corn
• Rice
• Sunflower
• Wheat
• A Major Marketing Advantage
• but lost when stacked with a transgene

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The Roundup Ready Story

• Glyphosate is a broad-spectrum herbicide

• Active ingredient in Roundup herbicide
• Kills all plants it come in contact with
• Inhibits a key enzyme (EPSP synthase) in an
  amino acid pathway

• Plants die because they lack the key amino acids

• A resistant EPSP synthase gene allows crops
• to survive spraying

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Roundup Sensitive Plants
Glyphosate
X
X
Without amino acids, plant dies
X
X
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Roundup Resistant Plants
Shikimic acid Phosphoenol pyruvate
Glyphosate
RoundUp has no effect enzyme is resistant to
herbicide
Bacterial EPSP synthase
3-enolpyruvyl shikimic acid-5-phosphate (EPSP)
With amino acids, plant lives
Aromatic amino acids
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The Golden Rice Story

• Vitamin A deficiency is a major health problem

• Causes blindness
• Influences severity of diarrhea, measles

• gt100 million children suffer from the problem

• For many countries, the infrastructure doesnt
  exist
• to deliver vitamin pills

• Improved vitamin A content in widely consumed
  crops
• an attractive alternative

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?-Carotene Pathway Problem in Plants
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The Golden Rice Solution
?-Carotene Pathway Genes Added
Daffodil gene
Single bacterial gene performs both functions
Daffodil gene
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Introducing the Gene or Developing Transgenics
Steps
1. Create transformation cassette
2. Introduce and select for transformants
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Transformation Cassettes
Contains
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Transformation Steps
Prepare tissue for transformation
Introduce DNA

• Agrobacterium or gene gun

Culture plant tissue
Field test the plants

• Multiple sites, multiple years

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Delivering the Gene to the Plant

• Transformation cassettes are developed in the lab

• They are then introduced into a plant

• Two major delivery methods

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The Lab Steps
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The Next Test Is The Field
Herbicide Resistance
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Final Test of the Transgenic Consumer Acceptance
RoundUp Ready Corn