“If you desire peace,
cultivate justice, but
at the same time
cultivate the fields to
produce more bread;
otherwise there will
be no peace.”
Norman Borlaug
GM Crops, from Science to Politics
L. Andrew Staehelin
Department of Molecular, Cellular and Developmental Biology
University of Colorado, Boulder
Food and Environment lecture 2013
Scientific Challenge
Eurobarometer 2003 Study
Is the following statement true?
“Ordinary tomatoes do not
contain genes, while genetically
modified tomatoes do.”
Only 36% of 17,000 respondents
across 17 EU countries correctly
identified this statement as false.
Agriculture - The cultivation of land to produce
crops for human consumption and use
• Foods
Proteins, Starch, Oils
• Industrial materials
Starch, Fibers, Oils
• Pharmaceuticals
Natural Chemicals (vitamins, omega-3 fatty
acids),
Vaccines, Antibodies, Protein Drugs (insulin)
The big problem
my birth
Industrial revolution
Can organic farming feed the world?
NO!
• Why?
• Organic farming is between 3% and 55% less productive
than traditional farming. It could not even feed the current
world population.
• Organic farming is also much more sensitive to
environmental challenges (insects, pathogens, drought).
Thus, its productivity is more variable than traditional
agriculture.
• Conclusion: organic farming does not provide an option for
feeding the world in the future.
How will we feed the growing world
population?
Agricultural challenges
• less agricultural land (urbanization, salination,
desertification)
• less water (competing uses, contamination)
• global warming
• the GREEN REVOLUTION has run its course
wheat
The Green Revolution was
driven in part by the
introduction of genes for
dwarfism: shorter stems ->
more seeds/fruits.
How can we produce more food?
Agricultural changes
• improve cultivation methods (fertilizer and water use)
•
improve storage and transport
Biological improvements
• reduce crop losses during/after cultivation due to insect pests,
pathogens, heat, water and salinity stresses
• increase productivity of plants (more seeds, bigger fruit)
• improve nutrient value (increased content of desired products,
e.g. protein to reduce need for meat)
Biological improvements require changes in genetic makeup!
Methods for changing genetic makeup of crop plants
Traditional breeding
• limited in scope to gene pool of given plant
• time consuming (~10 years) due to long generation times
Mutagenesis – radiation, chemical, tissue culture growth
• results unpredictable; limited in scope
Genetic engineering
• can utilize genes of all organisms (cis-genic, trans-genic)
• can add new genes or suppress the expression of existing
genes (silencing)
• more precise and faster than traditional breeding
Agrobacterium tumefasciens – a soil bacterium
DNA
Ti plasmid
Ti plasmid contains 25 vir genes, which can be injected into plant
cells by bacterium
T-DNA sequences in plasmid allow for the insertion of plasmid
genes into plant cell DNA
Vir genes code for enzymes for producing
• plant hormones (auxin, cytokinins) that promote uncontrolled
cell divisions (tumors)
• unusual amino acids (opins) that provide N- and C-sources for
the bacteria
The Agrobacterium transformation system
Modification of Ti plasmids for transformation experiments
•
removal of genes coding for opin synthesis enzymes
•
removal of genes coding for hormone synthesis enzymes
(no tumor formation)
•
insertion of desired gene plus selection marker gene into
emasculated Ti plasmid
Production of a transgenic plant
Plant cell
29 countries grew GE crops in 2010
(40 countries predicted to plant GM crops by 2015)
Clive James, ISAAA, 2011
2011: 160 million hectares (400 million acres) of GM crops – 8% increase over 2010
16.7 million farmers, 15 million in developing countries
GM crops permitted for planting
Bt crops expressing insecticidal Cry proteins: corn,
cotton, soybeans, potato, tomato
Roundup Ready crops resistant to the herbicide
glyphosate: soybeans, sugarbeets, rapeseed (canola),
alfalfa
Virus-resistant crops: papaya, squash
Bionutrient-enhanced crops: Golden Rice
Drought-resistant crops: corn
European corn borer protection by Bt cry-protein
Bt Corn
Non-Bt Corn
European corn borer
Sources: Monsanto, Clemson University
European corn borer
European corn borer damage to corn kernels:
Bt-Maize v. non-Bt-Maize
Fusarium molds (arrow) produce fumonisins, highly toxic chemicals,
that cause cancer and spina bifida babies
Damage from corn rootworm feeding - can be
controlled with Bt protein expression
Sources:
USDA, Iowa State Univ.
Bt crops
Crops: corn, cotton, soybeans, potato, tomato
Mode of action of Cry proteins
• Insect guts have alkaline pH, which converts the Cry protein to a
membrane pore-forming toxin
• In acidic intestines (mammals, birds, fish) the Cry proteins
remain inactive and are digested
Benefits of Bt crops
• Very effective for combating European corn borer, cotton
bollworm, and corn rootworm
• Farmers planting Bt corn and Bt cotton report using 30-70%
fewer pesticides, and having a 10-30% increase in yield
Methods for reducing the development of
resistance to Bt toxins
Crop rotation
Refuge plus high dose strategy
• planting of non-Bt refuges (~20% of acreage)
• use of crops with combinations of transgenes (e.g.
3 Cry genes for Lepidopteran pests and
3 Cry genes for Coleopteran pests
Integrated pest management systems
• use refuges, crop rotation and multitoxin Bt crops
• monitor crops for pests
• release of sterile insects
• apply specific insect growth regulators, feeding inhibitors
• apply narrow-spectrum chemical pesticides
Roundup Ready crops
Control soybeans
Roundup Ready soybeans
Source:
Monsanto
Roundup Ready crops are resistant to the herbicide glyphosate, which
enables farmers to kill weeds without affecting the crop plants.
Roundup Ready crops
Crops
• corn, soybeans, sugar beets, canola, alfalfa
Mode of action of Roundup (glyphosate)
•
glyphosphate inhibits the activity of the plant EPSPS enzyme
needed for the synthesis of aromatic amino acids
•
this enzyme is also found in many bacteria, but not in
humans and animals (glyphosate is non-toxic)
•
Roundup Ready plants contain bacterial EPSPS that is not
inhibited by glyphosate
Roundup Ready crop benefits
• Excellent weed control
• Rapid degradation of herbicide in soil -> no groundwater
contamination
• Increased productivity (less competition by weeds;
Boulder County sugar beet farmer: same yield on 80 acres
as previously with 130 acres)
• Allows for no-till farming, which conserves water and soil
(soybean farmers report a 90% reduction in soil erosion)
• Emerging problem: development of RoundupReady
resistant weeds
Papaya Ringspot Virus
Fig. 38.18
GM-papaya - protected from the
virus by the expression of a viral
coat protein in the papaya plants,
which causes gene silencing.
Developed by University of Hawaii scientists.
Papaya farming in Hawaii was
saved from extinction by these GM
fruits.
GM-papaya
control
Countries, where vitamin A-deficiency is a severe
public health problem
WHO 2008
Vitamin A deficiency causes child blindness (~500,000 cases
per year) and immune deficiency problems (~2 million deaths
per year).
Golden Rice produces beta-carotene, a precursor of
vitamin A
One bowl (3 to 5 oz) of cooked Golden Rice 2 per day can
provide 60% of needed vitamin A for young people.
Poor farmers in Bangladesh, Indonesia, Philippines, India(?) will be
receiving free Golden Rice seeds starting late 2013.
Examples of GM crops soon to be released
•
•
•
drought resistant corn (several companies) – now released
golden rice (Int. Rice Institute, Philippines) – now released
blight resistant peanut (Virginia Tech)
•
•
•
•
non-browning apple (Okanagan Speciality Fruits)
higher yielding soybean (Monsanto)
cold tolerant eucalyptus (Arbor Gene)
new herbicide resistant crops (Bayer, BASF, Dow, DuPont,
Monsanto, Syngenta)
By 2015 – 120 GM crops worldwide (50% will be crops
developed for local use in Asia and Latin America)
Greenpeace Demonstration
Side Note: Patrick Moore, co-founder of Greenpeace, has recently
become a vocal supporter of GM crops. He now accuses Greenpeace
of crimes against humanity for opposing the planting of Golden Rice.
GM Food Hysteria
Which federal entity regulates GE crops
in the U.S.?
U.S. Dept. of
Agriculture
Environmental
Protection
Agency
Food and Drug
Administration
Cost of going through the regulatory process is
estimated at $10-20 million.
Some concerns with GM crops
Ethical: Is GE technology playing God?
Economic:
• cross pollination introduces GE material into organic food
products
• concentration of seed business in the hands of a few companies
is risky
Food safety:
• do GE foods have adverse health effects?
• will GE foods provoke allergic reactions?
Environmental:
• development of Bt resistant insects and RR resistant weeds
• transfer of transgenes to relatives of crops
Why have genetically modified organisms
(GMOs) remained so controversial?
Genetically modified abominations
Jakub Kwiecinski - EMBO reports 10:1187-1190, 2009
A central function of society and culture is to impose order on
the natural world by projecting categories to classify and
structure nature. Societies like clear divisions: human and
nonhuman, female and male, etc.
Scientists perceive genes as information that is readily
exchanged between organisms. Many non-scientists regard
genes as things that maintain boundaries between species.
GMOs break the classical boundaries of fixed categories and are
therefore viewed as polluting the human system of ordering the
universe.
Cross-pollination from GE to organic fields
A major point of contention is that pollen from GE fields will
pollinate neighboring organic fields, resulting in some level of
transgenic material in the organic seed.
♂
♀
In corn, separate male and female flowers
and pollen dissemination by wind strongly
promote cross-pollination.
How far does corn pollen travel in Colorado?
Blue corn trial, Boulder County, 2002-2006
North
West
East
Blue Corn
Yellow corn
= sample of
10 ears
Sampling
distances up
to 1000 ft.
South
Byrne and Fromherz (2003) Food, Agric. & Envir. 1:258-261
Blue corn trial, south side, 2002
2.5 ft: 46%
150 ft: 0.53%
300 ft: 0.18%
30 ft: 14%
600 ft: 0.06%
Byrne and Fromherz (2003) Food, Agric. & Envir. 1:258-261
Percent cross-pollination vs. distance from
pollen source, blue corn trial, Boulder Co., 2004
14.00
% cross-pollination
12.00
10.00
most distant blue kernels:
918 ft SW, 0.05%
8.00
SE
SW
NE
6.00
NW
4.00
W
150 ft: 0.07 – 0.42%
2.00
0.00
0
150
300
450
600
750
900
Distance (ft)
Byrne and Fromherz (2003) Food, Agric. & Envir. 1:258-261
Challenges associated with the design and execution of
studies of GM food safety
European Union has developed strict guidelines for studies
Obtaining equivalent GM and non-GM foods is critical
• plants are masters of adaption to local growth conditions
(a plant has to be able to survive and reproduce wherever it germinates)
• good-bad wine vintages (precipitation and temperature affect
composition)
• local growth conditions affect composition: isoflavone (hormonelike compounds) levels of soybeans grown in different parts of Illinois
varied from 47mg/10g to 171mg/10g in same year
• natural toxin (aflatoxin, fumonisin) levels fluctuate
• feeding studies should use “isolines” grown in same place at same
time – complete chemical analysis needed
Challenges associated with the design and execution
of studies of GM food safety (continued)
Experimental design questions
• animal species? animal age? animal sex?
• animals need a balanced diet; what is an appropriate
amount of experimental food in diet (alfalfa, corn, potatoes,
papaya)?
• diets should include multiple concentrations of experimental
food -> concentration-dependent response
• duration of study?
• which health parameters should be tested?
Assessment of health impacts of GM diets using
feeding trials
by Chelsea et al. Food Chem Toxicol. 50:1134-1148, 2012
Review of 12 long-term studies of 90 days to 2 years, and
of 12 multigenerational studies (2-5 generations).
Animal types: mice, rats, cows, pigs, sheep, goats, hens, salmon.
High degree of compliance with European Union guidelines.
Conclusion: GM plants/foods are nutritionally equivalent
to their non-GM counterparts and can be safely used for
food and feed.
Effects of ratio of organic to conventional agriculture on
pest levels
by Adl et al. Sci. Total Envir. 409-2192-2197, 2011
Organic agriculture benefits greatly from the low levels of pests
maintained by the use of GM crops and pesticides by conventional
farmers.
Above a threshold level of organic to conventional farms the pest
population in organic plots grows rapidly causing epidemics of pest
outbreaks, a major reduction in organic farm output and in food
security.
Conclusion:
Too many organic farms are bad for organic farming!
Summary: Some benefits of GE crops
• Better insect pest control, reduced chemical insecticide
applications -> greater yield
• Better weed control -> greater yield
• Drought tolerance -> greater yield
• Facilitates no-till farming for soil and water conservation.
• Effective viral, bacterial and fungal disease control
• Improved nutritional properties (Golden rice);
pharmaceuticals
• Greater profitability, shared throughout the agricultural
system
Comparison of timelines for producing plantmade and egg-based vaccines
DAY
0
21
75
96
150
A: pre-production (plants: cloning and transformation;
egg-based system: preparation of vaccine strain)
B: Production time for first batch
C: Estimated 2.5 months for testing and regulatory
approval
Penney et al. (2011) Plant Cell Rep. 30:789-798
Experiment to gage consumer attitudes towards
GM foods via fruit stand sales
(Countries: New Zealand, Sweden, France, Belgium, UK, Germany)
Fruit “types”:
• Organic (certified)
• Conventional (low spray)
• GM spray-free
Price levels:
prevailing market price +/-15% (combinations)
Note: customers were informed of the experiment after they had made
their selection, but before money had changed hands (ethics rule)
(Nature Biotechnology 25:507-508, 2007)
Market share simulation comparing revealed
versus preferences stated in surveys
Price level: 15%
ORGANIC
ORDINARY
SPRAY-FREE
premium for organic;
15% discount for sprayfree GM
“Biogrow certified”
“Low residue”
“Genetically Modified”
NZ:
Revealed
Stated
20%
38%
20%
32%
60%
30%
Sweden: Revealed
Stated
20%
39%
38%
30%
43%
31%
Germany: Revealed
Stated
33%
28%
31%
59%
36%
12%
Fruit stands were visited by 2,736 customers in six countries
(Nature Biotechnology 25:507-508, 2007)
Findings
• Across 6 countries it appears that 30-40% of
consumers either don’t care, don’t notice, or
like the idea of spray-free GM fruit
• This proportion goes higher at discount prices
• Revealed preferences do not match stated
preferences
(Nature Biotechnology 25:507-508, 2007)
Golden Rice – development time and costs
PP
IPP
PP
DMAPP
PP
GGPP
Phytoene
Phytofluene
-Carotene
Neurosporene
It took a total of 9 years of
basic research and
engineering in the
complementing teams of
Ingo Potrykus and Peter
Beyer and $ 2.4 million to
establish the biochemical
pathway.
It took, however, additional
13 years and $ 22 million to
develop a GMO-product
and pass it through
regulation.
Lycopene
Golden rice seeds developed by the International Rice Institute are being made
available to poor farmers free of charge in Asia.
U.S. adoption of genetically engineered crops
Percent of acreage
100
91
88
85
Cotton
80
Soybean
60
40
Corn
20
1996
1998
2000
2002
2004
2007
Compiled from USDA annual estimates
2009
Cotton bollworm
Cotton bollworm damage
Cotton bollworm
Photos: USDA