Genetic
Engineering
Pros and Cons
Is
Biotechnology Good?
What is biotechnology?
l Office
of Technology Assessment (Congress)
Any technique that uses living
organisms, or substances from these organisms, to make or modify a product, to improve
plants or animals, or to develop microorganisms for specific uses
Genetic Engineering
l Recombinant
DNA technology
Process of inserting new DNA into a new DNA strand
Involves cutting and splicing of genes
Assisted by restriction enzymes specific to one
specific chromosomal site
Selecting the right enzyme is the key to cutting and
splicing
Restriction Enzymes
l
Protein enzymes that recognize
specific nucleotide sequences and cleave both strands of the DNA containing
those sequences.
l
Commonly used restriction enzymes always cleave the
DNA strands at a fixed position relative to the recognition sequence.
Restriction Enzymes
l Restriction enzymes and
the fragments produced by them have been powerful tools of molecular genetics.
They are used
to map DNA
molecules physically,
to prepare molecular probes,
to analyze the modification
status of the DNA,
and other applications.
How Is It Done?
l Mediated
by a Agrobacterium tumefaciens vector
Natural soil born bacteria that causes crown gall
Able to transmit DNS into infected cells
Used to place Bt delta endotoxin producing gene into
cotton, tobacco, and potato
Doesnt work well with cereal crops
How Is It Done?
l Gene
gun technique
Shoots tiny gold covered genetic material thru plant
cell walls
Done with a helium blast
Done with Bt Cry1Ab and Cry1ac genes
Successfully placed into field and sweet corn
Comparison With Traditional Breeding
l Speed
of incorporation
l Addition
of more that one toxin or resistance factor
l Size
of research program
l Protection
of intellectual property
Specific Examples
l 80
million acres grown in U.S
Cotton
Field Corn
Potato
Sweet Corn
l Eggplant
Bt Cotton
l Introduced in 1996
l Good against cotton bollworm, tobacco budworm, and
pink bollworm
l Resistance already occurs
Bt Potatoes
l Introduced in 1997
l Effective against Colorado potato beetle
l Grown in most areas impacted by CPB
Bt Field and Sweet Corn
l Introduced in 1996
l Effective against European corn borer, corn earworm,
and Southwestern corn borer
l Not widely grown
Bt Eggplant
l Developed here at Rutgers
l Effective against CPB
l Looking at homeowner market
l Not yet released
Problems
l Gene flow to other organisms
l Impacts on non-targets
l Pest resistance
l Loss of traditional Bt products
Gene Flow to Other Organisms
l Has
been demonstrated in weeds
Safflower
Create super weeds
l Not
yet demonstrated with Bt varieties
Could create a major problem
Elevate non-pests to pest status
End the plant-insect arms race
Impacts on Non-targets
l Bt Corn pollen impact on monarch butterflies
l Bt corn pollen killed larvae in laboratory
l Not yet demonstrated in field
l Not considered really a problem
Pest Resistance
l Could
rapidly generate resistance in pest populations
Extremely high selection pressure
Monogenic vs. polygenic traits
l Already
happened in cotton
l How
to prevent it from occurring
Loss of Bt Products
l Could
impact certain vegetable crops
l Could
impact organic agriculture
l Bt products
make up a substantial part of homeowner markets
l Could
impact Gypsy moth control
l Could
impact mosquito control
Current Theory
l Expression
only in the plant part needing protection
l Stacking
of two or more genes in a variety
l Sublethal
doses used in conjunction with natural enemies
l Create
refugia
l Mixed
planting of susceptible and resistant plants
So what do you think?
RETURN
