Transcript transgenic crops

By Sean Merrett and
Melissa Slingerland
• are also known as genetically modified or GM crops
• A transgenic crop plant contains a gene or genes which have been artificially
inserted instead of a plant acquiring them through pollination.
•The inserted gene sequence (transgene) may come from another
unrelated plant, or completely different species.
• Throughout history all crops have been genetically modified from their
original wild state by domestication, selection, and control of breeding
over long periods of time.
• Genetic engineering speeds up the process and increases the variety of
genes which can be inserted into a particular plant.
An Overview of the Crop Genetic Engineering cycle
This was the first “genetically modified” food approved by the
FDA in 1994. It was eventually pulled off the market in 1997
because of the controversy surrounding it. Questions arose
about it’s effects on human health, the environment, potential
gene transfer, and the creation of “Frankenfood”.
Flavr Savr
The Flavr Savr tomato ripens
on the vine – resulting in fuller
flavour. It is modified so that it
remains firm after harvesting.
Traditional
The traditional tomato must be
harvested while it is still green
and firm so that it is not crushed
on the way to the supermarket.
The traditional tomato is
sprayed with ethylene
after shipping to induce
ripening.
Ripe and Increased Flavour.
Ripe but decreased Flavour.
Worldwide production area of transgenic crops and traits (source: Science 286:1663, 1999).
Crop
Area planted in 1999 (millions of acres)
Soybean
53.4
Corn
27.4
Cotton
9.1
Canola
8.4
Potato
0.3
Squash
0.3
Papaya
0.3
Trait
Herbicide tolerance
69.4
Bt insect resistance
22.0
Bt + herbicide tolerance
7.2
Virus resistance
0.3
As of 2003, the Canadian government has approved over 60 genetically modified
foods for sale in Canada. Some of these include:
insect resistant corn
herbicide tolerant soybean, sugarbeet, corn, and rice
virus resistant squash
insect and virus resistant potato
Control Mechanisms used by Seed Companies
• Technology Protection System, also known as the “terminator”,
incorporates a trait that kills developing plant embryo’s so seeds
cannot be saved and replanted in subsequent years
• “Traitor”, also known as Trait-specific Genetic Use Restriction
Technology incorporates a control mechanism that requires
yearly applications of a propriety chemical to activate desirable
traits in the crop
• the farmer can save and replant seeds but cannot gain the
benefits of the controlled traits unless he pays for the
activating chemical each year
• improved nutritional quality
• increased crop yield
• insect resistance
• disease resistance
• herbicide resistance
• salt tolerance
• biopharmaceuticals
Weed-infested soybean plot (left) and
Roundup Ready® soybeans after Roundup
treatment. Source: Monsanto
• saving valuable topsoil
• ability to grow plants in harsh environments
•Damage to human health
•allergies
•horizontal transfer and antibiotic resistance
•eating foreign DNA
•changed nutrient levels
•Damage to the natural environment
•crop-to-weed gene flow
•leakage of GM proteins into soil
•reductions in pesticide spraying: are they real?
•Disruption of current practices of farming and food production
in developed countries
•crop-to-crop gene flow
•Disruption of traditional practices and economies in less
developed countries
• Lack of research on consequences of transgenic crops
• disruption of natural ecosystems
• introduction of diseases
• creation of biological weapons
• ethical dilemmas
• ie. Could human genes be
inserted into new crops?
http://dragon.zoo.utoronto.ca/~jlm-gmf/T0501D/introduction.html
http://www.colostate.edu/programs/lifesciences/TransgenicCrops/animation.html#
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/TransgenicPlants.html#Terminator_Genes
http://images.google.ca/imgres?imgurl=www.carascissoria.com/images/poli/frankenfood.jpg&imgrefurl=http://www.
carascissoria.com/general/singles/6173.htm&h=310&w=234&sz=33&tbnid=4aYYWnTCTGMJ:&tbnh=111&tbnw=
84&start=2&prev=/images%3Fq%3Dfrankenfood%2Bpictures%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%
3DN
http://www.inspection.gc.ca/english/sci/biotech/safsal/gmoogme.shtml
http://www.greenpeace.ca/e/campaign/gmo/backgrnd/index.php
Whitney, E.N. and Rolfes, S.R. (2002). Understanding Nutrition (9th edition). Belmont, CA:
Wadsworth/Thomson Learning.