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Agricultural Biotechnology:
Genomic Approaches to Monitoring
the Effects of Genetically Modified
Crops
Uwe Stolz
NERL Postdoctoral Research Fellow
Genomics Workshop, Chicago, IL
April 29, 2005
Agricultural Biotechnology:
Genetically modified crops
Current and Future GM
Crop Traits
1. Insect Resistance (Plant Incorporated
Protectants) – ex: BT corn & cotton
2. Herbicide Tolerance – ex: Glyphosate Resistant
Corn & Soybeans (i.e. Roundup Ready)
3. “Value Added” Crops – ex: Golden Rice
containing vitamin A
4. Stress Tolerance – ex: drought, salt resistant
varieties
5. “Biopharming” – Production of drugs, chemicals
on agricultural scales
Major environmental and health
concerns regarding GM crops
• Non-target effects
• Gene flow /
Transgene Escape
• Insect Resistance
• Allergenicity
Issues for Regional
Monitoring Efforts
• Non-target Effects
 Species, Communities, Ecosystems
• Beneficial species, threatened / endangered
species
• Gene Flow / Transgene Escape
 Crop to Crop, Crop to Wild Relative,
Crop to distant relative
• Insect resistance genes, herbicide tolerance
genes
• Future – vaccines, chemicals, drugs, etc.
Non-target effects of GM corn
1. Bt corn and non-target effects:
Yieldgard Corn
2. ORD/NERL research approach /
rationale
3. Research progress
4. Monitoring Applications
Agricultural Pesticides:
Intended and unintended effects
Unintended
Environmental
Impact
Targeted
Insect
Pest
Human Health
Effects
80 million acres of corn planted per year
(20% of total crop acreage)
Western Corn
Rootworm (WCR) is
major pest of corn.
Conventional insecticides
applied to 14-18 million
acres per year.
WCR
damage
WCR responsible for 1
out of 7 insecticide
applications for all
agricultural crops
CRW will continue to be a problem…
Infested acres of CRW expected to
increase: 39 million acres by 2013
CRW have adapted to crop
rotation with soybeans and
have evolved resistance to
several chemical
insecticides
EPA identified 10 insecticides used
in agriculture as the most toxic to
birds - 3 currently used to control
corn rootworm (carbofuran,
phorate and methyl parathion).
Bt-corn reduces the need for
conventional pesticides:
Bt-corn
Non
Bt-corn
The Evolution of Bt-Resistance is an
Environmental Problem
?
Current Research of ORD NERL in Cincinnati
• Monitor resistance genes in pest populations
-Identify resistance/tolerance genes
-Develop molecular techniques for rapid and cost
effective screening
• Monitor non-target species for effects of Bt
exposure
-Identify gene expression markers for Bt exposure
in target pests
-Develop assays to test for effects in related nontargets
Advantages of Genetic Monitoring
Complements ecological monitoring by
adding another level of analysis and
increases the amount of information that
can be gathered about the status and health
of species
Non-Target-Monitoring
• What is a non-target species?
• How do we choose non-targets?
• Molecular genetics to monitor
non-targets
 Gene Expression
• Benefits of molecular genetic
techniques
Non-Target Effects: The Agricultural
Landscape
Non-economic
?
?
?
Economic
Non-Targets
• Economic non-targets
 Non-target pests
 Beneficial predators
 Other beneficial Insects
• Non-Economic non-targets
 Threatened/endangered species
 Species of public concern
 Species whose primary habitat is not
agricultural
Gene Expression
•
•
•
•
•
Detects exposure to pesticides/PIP
Detects biologically meaningful exposure
Detects non-acute effects
Permits study of non-lab species
Highly sensitive - ex: EDCs in streams
1
Bt Corn
DIET +ROOT
STD DIET
WCR
2
DIET +ROOT +BT
bt
3
4
5
6
Gene Expression Changes
Results from QPCR for six clones
identified through differential display.
Effect of Bt-corn diet on gene
expression
Relative Gene
Expression
9.00
cnt
8.00
7.00
bt
6.00
5.00
4.00
3.00
2.00
1.00
0.00
7A(1.21)
7D(4.23)
4A4(6.85)
4B1(6.18)
clone name
6A1(2.82)
6A2(1.82)
Once Gene Expression
Markers Confirmed
•Non-target species can be
monitored for exposure to PIPs
and/or pesticides (QPCR, RTPCR)
•Several closely related species
can be monitored at the same
time to detect ecosystem level
patterns
Proof of Concept Research
•We are examining ground beetle species
across corn growing areas
•Examine several species communities
•Look at exposure to Bt corn
-ELISA assays using beetle guts to check for
presence of Bt toxin
-Gene expression assays
Gene Flow / Transgene Escape
Major Issues of Transgene
Escape / Gene Flow
•
•
•
•
Contamination of food supply
Creation of “super-weed” crops
Transgene escape to native relatives
via hybridization, creation of superweeds
Genetic pollution
Keys to Prevention of
Transgene Flow
• Use GM crops with few wild relatives (ex:
Corn in the USA, Canada, Europe)
• Use GM crops with no weedy relatives (ex:
Sorghum and Johnson Grass)
• Provide sufficient physical and physiological
barriers to gene flow (ex: plant isolated
patches, have appropriate borders, sterility)
• Monitor for the escape and movement of
transgenes
Case Study of EPA work on
Transgene Flow
• Herbicide
(Roundup)
resistant bent
grass
• Considered for
turf management
• Improve golf
courses
CD = managed
bentgrass field
Sentinel plants =
potted plants
Resident = naturally
occurring
In addition to PCR, also used Elisa
(checks for protein product of transgene)
and used seedlings from sentinel plants to
check for RoundUp resistance (phenotype
of transgene).
Ultimate Goals
• Apply molecular monitoring methods to
conserved, threatened, and endangered
species (i.e. difficult to study in the lab).
• Apply strategy to species / populations /
communities that are most at risk to
changing crop practices.
• Ensure the safety of biotech crops by
monitoring potential environmental
problems.
Acknowledgements
Ecological Exposure Research Division/
Molecular Ecology Research Branch
Mark Bagley
Jim Lazorchak
Sobran Inc.