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Genetically Modified Organisms
Image: www.ars.usda.gov
GMOs: Genetically Modified Organism
Any organism that has had it’s genetic material changed
or manipulated in some way, usually as a result of
human intervention.
Image: www.life.uiuc.edu
This is the ancestor of what crop?
Image: www.aggie-horticulture.tamu.edu
Strawberries with fish genes?
Anti-freeze proteins in strawberry
and tomato plants
http://www.geo-pie.cornell.edu/media/fishberries.html
Trait targets of traditional plant breeding
• Increase size (yield) of
fruit or grain
• Height of plants (taller
OR shorter)
• Flowering time to
increase the number of
crops in a year (rice)
• Drought or cold
tolerance
• Appearance for
ornamentals
Image: www.news.cornell.edu
Image: http://faculty.etsu.edu/mcdowelt
Image: www.dlc.fi
Image: www.jacksonandperkins.com
Traditional breeding is limited to available genetic material in
closely related species
Traits for genetically engineered organisms
• Increase nutrient content (example:
Golden Rice)
• Delay ripening of tomatoes for
better shipping (example: Flavr-savr)
• Resistance to naturally occurring
pests (example: Bt cotton)
• Resistance to otherwise harmful
herbicides
(example: RoundUp Ready
soybeans)
Image: www.scidev.net
If there is a gene out there, it can be used,
regardless of the source.
GMO Labelling
• Currently, only two
products on the
market are “labeled”
for altered nutrient
content:
• High laurate canola
• high oleic soybean
http://www.carleton.ca/catalyst/2005/s9.html
Agrobacterium tumefaciens: transfer of DNA into plants
• Naturally occurring soil
bacterium that causes
crown gall disease
• Bacteria contains the Ti
(tumor-inducing) vector- a
plasmid we can
manipulate!
Image: www.arabidopsis.info/students
Ti vector: modified for genetic engineering
• Remove the tumorinducing genes
• Replace with gene
of interest and
promoter
• Anything between
the R and L border
will be transferred.
Bt: example of genetic modification
• Bacteria called Bacillus
thuringiensis makes a protein with a
crystal structure
• The protein, when eaten by
lepidoptera (caterpillars), sticks to
the gut wall of the insect
• Causes starvation and the
dissolving of the internal organs
• Purified protein has been used by
organic farmers for years as a spray
(is this a pesticide or herbicide?)
Images: www.deh.gov.au
GMOs in the Market
At least 70% of processed foods contain
genetically modified ingredients:
• Corn- in packaged foods (corn
syrup, corn starch, etc.)
• Cotton- Cotton isn’t just clothing:
cottonseed oil is present in many
food items
• Soy -in packaged foods and animal
feed
• Canola- the healthy oil
http://www.ers.usda.gov/data/biotechcrops/
Genetically modified foods: Others
• Papayas
• Radicchio
• Potatoes
• Flax
• Tomatoes
• Rice
• Sugarbeets
• Squash
Image: www.ebfarm.com
Image: www.seedexseed.com
• Cantaloupe
• Wheat
• Banana
• and more...
While these have been modified and approved,
you are most likely not eating these
Modifications currently approved
• Herbicide tolerance (soy, cotton, corn, radicchio,
sugarbeet, flax, rice, bentgrass, wheat, alfalfa)
• Pesticide production (cotton, corn, potato,
tomato)
• Disease resistance (papaya, squash, potato,
plum)
• Delay in ripening (tomato, cantaloupe)
• Improved (healthier) oil content (canola,
soybean)
• Reduced nicotine content (tobacco)
• Increased amino acid content (corn)
On the SF
bart…
What do
you think?
Genes for which we are testing: RuBisCo, Bt, 35S
•
RuBisCo- 599 bp- found only in plants. An
enzyme that converts carbon dioxide into sugars
and carbohydrates for the plant. This is our
internal control. Most abundant protein found in
nature.
•
Bt- 421 bp cry gene (toxin gene) will indicate
that the plant is genetically modified
•
35S promotor of the cauiliflower mosaic virus
(CaMV 35s 221 bp -promoter element common
in most transgenic plants. Its the “start” of a
gene. Also indicates the plant is genetically
8/07
modified)
NHM
Testing for GMOs in the field or pantry
ELISA uses a color-change system to signal the
presence of a protein. Limits: protein must not be
denatured, as is often the case in processed foods.
www.ilcrop.com
PCR uses gene-specific primers to detect the presence of
the transgene itself. Limits: expensive, not able to do in
the field.
* Enzyme-Linked ImmunoSorbent Assay
Golden Rice
• Staple food world-wide is deficient in Vit. A
• Ingo Potrykus, et al. developed rice that
produces beta carotene, precursor to Vit. A
• Still not available for human consumption
www.goldenrice.org
Hawaiian papayas
• Papaya ring spot
virus found in
Hawaiian crops
• Cornell and Univ.
Hawaii researchers
developed papaya
that produces viral
coat protein
www.ctahr.hawaii.edu
DNA cassette
PROMOTER
GENE OF INTEREST
SCREENABLE/ SELECTABLE MARKER
Genetically modified foods: Corn
• Bt to protect from European
corn borer
• RoundUp Ready (or other
herbicide tolerance), to allow
spraying of herbicides
Image: msucares.edu
• Stacked varieties
• Corn and corn derivatives are found in almost all
packaged foods (corn syrup, corn starch, etc.)
• In 2009, 85% of U.S. corn planted was genetically engineered
Genetically modified foods: Soy
• Herbicide tolerance is the only
modification of soy
• Soy and derivatives are found in
most packaged foods
• Important as animal feed
• In 2009, 91% of soy planted in
the U.S. was engineered
Image: cropwatch.unl.edu
Genetically modified foods: Cotton
• Both Bt and herbicide
tolerant varieties
Image: ipm.ncsu.edu
• Cotton isn’t just clothing:
cottonseed oil is present
in many food items
• In 2009, 88% of U.S. cotton planted was engineered
3. There are 2 sequences of DNA that are most
associated with GMO’s.
1. 35 S promotor of the cauiliflower mosaic
virus (CaMV 35s)
2. Terminator of the nopaline synthase (NOS)
gene of Agrobacterium tumefaciens.
5. We will look for either or both of these
sequences in the food that we test.
6. PCR will allow us to isolate those segments of
DNA and copy them.
7. An electrophoresis will give us a visual of the
segments.
Genetically modified foods: Canola
• Herbicide tolerant varieties
• Canola is touted as one of
the “healthiest” oils
• In 2005, 80% of Canadian
canola was engineered
Image: canola-council.org
8/07
NHM
DNA
sequence
based on
a known
gene
gene
of
interes
t
(goi)
Plasmid (circular DNA from bacteria)
+ ligase and
open plasmid
Host DNA
Electroporate into
Agrobacterium tumefaciens
gene
of
interest
selectable
marker
plasmid
leaf disks
Transfer to shoot and root
growth media
Screen for transformants
using selectable marker
Incubate leaf disks
with Agrobacterium
Each cell of the plant contains
the new gene of interest
Agrobacterium injects the
gene of interest into the plant cell
nucleus
Pot transformed plants
and propagate
The gene of interest is
inserted into the
chromosomes of the plant
with helper proteins
PCR is a method to amplify
DNA
Transfer genes by transformation- what do
you need? A plasmid
The bacteria Agrobacterium has a Ti
plasmid (tumor inducing plasmid) that
allows you to insert new genes (foreign
DNA) regardless of size). Normally Ti
causes tumors
Scientist have engineered a cassette
(sequence of genes) and are able to insert
new genes much more easily.
Bt gene confers resistance to insects
B. GMO PCR product
Check plant pcr: is there a 455 bp band
from GMO + (lane 5)?
Check GMO PCR: is there
a 203 bp band from GMO +
(lane 6)
Types of genetic modification in plants
• Selective breeding
– selecting traits
– marker assisted breeding
– radiation/ mutagen induced
• Hybridization (triticale)
• Grafting (rootstock and scion)
• Genetic engineering
Image: farrer.csu.edu.au