Current Status of GE crops worldwide facing challenges€¦ · Why farmers like Bt crops Bt crops...
Transcript of Current Status of GE crops worldwide facing challenges€¦ · Why farmers like Bt crops Bt crops...
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Current Status of GE crops worldwidea. What crops have been commercialized?
b. What are the potential and current positive and negative impacts (benefits/risks)
Cholani WeebaddeMichigan State University
Global food production – facing challenges
• Challenge: By 2050 we need to double food production to feed the projected 9.2 billion people using less resources (fossil fuel, water & nitrogen) (7.6 billion people today; just 17 years after 6 billion)
• How: Need to increase crop productivity by integrating best of conventional crop technology & best practices of crop biotechnology applications including novel traits
High productivity paths to Agriculture
• Green revolution vs. “Industrial” farming– Traditional farming – Pre 1980s (where we were)
• Excessive use of water, fertilizer, pesticides, diesel fuel and excessive tilling of soil
– Precision farming – Post 1980s (where we are…)
• New irrigation technologies, more precise use of fertilizer, controlled use of pesticides, reduced tillage to save diesel fuel
• Biotech/GE crops fit into Precision farming: Seeds with novel traits to make crops better adapted to biotic and abiotic stresses
Bt Corn protects against corn borer damageSource: Robert Paarlberg
How is a GE/GMO crop different from Traditional and Marker Assisted Breeding?
Source: ISAAA 2016
….the “big four” GE crops adopted
For GE crops adoption rates in specific countries, please refer to ISAAA Brief 52: https://www.isaaa.org/resources/publications/briefs/52/download/isaaa-brief-52-2016.pdf
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A steady increaseSource: Crop BioetchUpdate, July 27, 2016
Why farmers like GE crops - USA
• Protect against crop losses from diseases and weeds
• Higher returns per hectare
• Reduced pesticide use and costs
• Ease of production with large farms (less time spent on the tractor spraying pesticides or cultivating fields)
If you consider insect and herbicide tolerant crops;
GE crops commercialized in the US
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Can
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Alf
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Pap
aya
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Squ
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Ap
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2016
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Source: https://gmoanswers.com/current-gmo-crops
All GMO crops in the US market have gone through the regulatory application and approval process…
Source: https://gmoanswers.com/current-gmo-crops
Traits of GE crops commercialized in the US
Traits – Insect resistance (Bt), Herbicide tolerance (eg. RR), Resistance to viruses, Resistance to fungi, Drought tolerance, Non-browning
The science behindBt Insect Resistant
Biotech Crops
Why did scientists develop Bt crops?
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• Bt – Bacillus thuringiensis
• Common soil bacterium
• Produces crystal (Cry) proteins during sporulation
• Different strains of Bt produce different Cry proteins that are toxic to a variety of insects
• Led to development of Bt insecticides against insect pests
Bt insecticides generally contain a mixture of several proteinsExample: Dipel = Bt kurstaki (Btk)Cry1Aa, Cry1Ab, Cry1Ac, Cry 2Aa, + Cry2Ab
Bt and its importance for Agriculture
Activation of toxin:- crystals solubilizedunder high pH
- protein cleavedby gut proteases
Ingestion ofspores,crystal
proteins(= protoxins)
Toxin binding to gut receptors:- paralyzes gut- insects stops feeding- gut membrane leaks- bacteria multiply in body- septicemia
Slide of Chris DiFonzo
How Bt acts as an insecticide
Mammalian Toxicity, rats
cyhalothrin 79-144 mg/kg
carbosulphan 90-250 mg/kg
cypermethrin 250-2000 mg/kg
Bt kurstaki > 5,000-24,000 mg/kg
-Human gut has low pH
-Humans don’t have the gut receptors
When comparing Bt to other insecticides,
Bt is sometimes referred to as
“practically non-toxic” –Why?
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Source: Chris DiFonzo
Why Bt is “practically non toxic” to humans
Bt is a common insecticidal spray used in organic agriculture, on sensitive habitats, and home gardens
But, it has limitations…..
Insect larvae are the most susceptible to Bt
1. Timing is crucial (have to spray at larval stage and spores must be eaten by larvae)
2. Need to scout large fields to time applications right
3. Bt gets exposed to UV and breaks down fast(within hours) – have to apply again repeatedly
• Spraying large fields
requires hiring of
equipment (coverage)
• Repeated applications
add cost
• Spraying Bt on large
farms is not cost effective
compared to pesticides
Bt sprays are not economical for large fields in the US
Bt Crops developed to address
limitations of Bt insecticides
– Coverage – 100% since all plant parts make
the insecticide
– Timing – Insecticide is made all the time
– Breakdown – Insecticide is within the plant
in high dose (not exposed to UV)
– Cost – Is part of the cost of seed (no
additional costs required for application)
Why farmers like Bt crops
Benefit: Less damage from
European corn borer. Less
pesticides needed for control
Added benefit: Insect damage
attracts secondary infections
with fungi that produce
mycotoxins toxic to humans
Why farmers like Bt crops
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Yieldgard RW- trace feeding
Untreated Corn- severe feeding- lodging, goosenecking
Soil insecticide Herculex RWUntreated
Makes machine harvesting difficult!! – yield loss
Soil insecticides used:Broad spectrum, difficult to apply, depends on soil moisture
Bt corn seed – no calibration, handling of pesticide, targeted for the pest
Why farmers like Bt crops Bt crops have reduced the amount of insecticides used in the fields…
- An issue that comes after the general release of a Bt crop. Therefore, we can only take measures to delay the occurrence of resistant pests
These issues are not new or unique to GE crops. Many insects and weeds have evolved resistance to pesticides in the past requiring more toxic pesticides for their control
However, high selection pressure increases chance of pests developing resistance to GE crops….
https://www.nature.com/news/crispr-microbes-and-more-are-joining-the-war-against-crop-killers-1.21633
In fact, field resistance to Bt sprays were observed before GE crops were commercialized….
We can expect the same to happen with Bt transgenic crops in the field….
First reports of high resistance to Bt sprays in the field was found in Hawaii, Florida and New York in the US; and in Malaysia in 1990, 30 years after commercial use of Bt sprays (and six years before Bt crops were first commercialized)
Laboratory experiments to test development of pest resistance against Bt…
• Thirteen different insect colonies developed resistance when exposed to Bt in the lab including:
• European corn borer, tobacco budworm, pink bollworm moth, Egyptian cotton leafworm, cottonwood leaf beetle, beet armyworm etc.
Scientists expected the same could happen with Bt crops in the field if not managed properly….
Source: Nappl, 2000
Strategies were put in place for delaying resistance from occurring….
• Use of a high dose strategy where both susceptible (rr) and partially resistant (Rr) types are killed
• Use of Refuge area to maintain a susceptible (rr) population so that through mating with RR, only Rrtypes are produced (and killed from high dose)
• Pyramiding multiple resistance genes (stacked genes)
• Use of cultural practices
However, 5 insect pests developed resistance to Bt crops…
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CONCLUSION: “Although regulations in the United States and else- where mandate refuges of non-Bt host plants for some Btcrops, farmer compliance is not uniformly high and the required refuge percentages may not always be large enough to achieve the desired delays in evolution of resistance. Both in theory and practice, using Bt crops in combination with other tactics as part of integrated pest management may be especially effective for delaying pest resistance
Reduction in the use of insecticides in the US upon adopting Bt corn and cotton crops
Source: Jorge Fernandez-Cornejo, Seth J. Wechsler, and Michael Livingston, 2014
“Pounds of insecticide (per planted acre) applied to corn and cotton crops have decreased steadily over the last 10 years (except for cotton in 1999-2001, when application levels were distorted during the boll weevil eradication program)”
However, complete control of the primary pests allow secondary pests to become more prominent
Therefore, strategies need to be put in place to control secondary pests…
Percent reduction of pesticide use in Bt Cotton compared to conventional (adapted from Fitt et al. 2004)
Sanvido et.al, Oct 2006
BollgardII – (Cry1Ac/Cry2Ab2) - 92% reduction
Additional resistance to secondary pests of cotton
• Cotton – highly susceptible to several serious insect pests (primary & secondary);– budworm-bollworm complex with considerable damage
• Control of secondary pest may require different genesBollguardII has Cry1Ac/Cry2Ab2
• Second gene is affective against secondary pests (soybean and cabbage looper, saltmarsh caterpillar, beet and fall armyworm)– One gene: 43% reduction– Two genes: 92% reduction
Use of an additional gene allows control of the secondary pests in cotton…
Will need to be a continuous effort….
The science behindRound-up Ready/Glyphosate
Herbicide Tolerant Biotech Crops
Why did scientists develop RR crops?
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Glyphosate mode of action
Source: Jim Kells
Shikimate
PEP
EPSP
TyrosineTryptophanPhenylalanine
Glyphosate
EPSP Synthase
Glyphosate (herbicide) blocks action of EPSP Synthase – 3 essential amino acids not made
Mode of action: Glyphosate tolerant crops
Source: Jim Kells
Shikimate
PEP
EPSP
TyrosineTryptophanPhenylalanine
Glyphosate
EPSP Synthase
Insert an EPSP Synthase with an altered binding site
Why farmers like Round-up Ready crops?
• Weeds are a major production constraint for crops
• A vast amount of toxic herbicides are used for weed control
• Once herbicides are sprayed, need to wait for herbicide to degrade before planting the crop to avoid damage
Weed control with
Glyphosate
Weeds not controlled
HT crops – impact on tillage practices
• Use of Round Up Ready crops was correlated with increase in reduced tillage or no-till practices
• Environmental considerations: tillage exposes soil to wind and water erosion which can carry both soil and agricultural chemicals
• Reduced tillage can – reduce erosion, groundwater contamination, and
conserve nutrients and organic matter– increase soil insect and microbial populations– reduce soil compaction resulting from passages across
the field
- indirect (unexpected) advantage
Recent data on tillage practices…
Source: Jorge Fernandez-Cornejo, Seth J. Wechsler, and Michael Livingston, 2014
However, high selection pressure increases chance of weeds developing resistance to HT crops….
Other more toxic herbicides are being reduced – that’s good
Use of Glyphosate has increased –selection pressure is very high
https://www.nap.edu/read/12804/chapter/2#3SOURCE: USDA-NASS, 2001, 2003, 2005, 2007, 2009a, 2009b; Fernandez-Cornejo et al., 2009.
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However, with increased selection pressure, weeds develop resistance to Glyphosate
Source: Chemical & Engineering news, 2015
Weeds resistant to Glyphosate in the US
Development of resistance to herbicides is not new to GE crops
Source: Ian Heap, Herbicide resistant weeds, 2014
Responsible use of technology is
important!
Genetic engineering can be used to make GE crops with stacked traits too!
We can also insert both Bt and RR ready genes in to a plant to
make it resistant to insects as well as be tolerant to herbicides!
Remove all genes needed to make a crown gall – “don’t make a crown gall”
Cry3Bb1
Cry 1F
Roundup Ready
Stacking genes allows you to develop one GMO with multiple traits such as a) Herbicide toleranceb) Resistance to corn borerc) Resistance to corn
rootworm
Stacked traits are gaining more popularity compared to single traits…
Example: SMARTSTAX (with 8 genes!)
• U.S./Canadian approval, 20 July 2009
Dow AgroSciMonsanto
Herbicide Tolerance Liberty LinkRoundup Ready
CornBorer
Rootworm
Cry 1FCry 1A.105Cry 2Ab2
Cry 34 Ab1Cry 35 Ab1Cry3Bb1
Source: Chris DiFonzo
You can also pyramid more resistance genes for the same pest in a stack
Cry 1A.105
Cry 2Ab2
Cry 1F
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Economic benefits from growing GE crops from 1996 – 2014 and 1996 - 2015
Cost of production reduced due to less ploughing, use of fewer pesticides and less labor involved
Environmental benefits of GE crops
The science behind
Virus resistant GE Crops
Why did scientists develop virus resistant crops?
Why was virus resistant Papaya developed?Threat from Papaya Ring Spot Virus
(PRSV) in Hawaii
1940 – PRSV discovered
1950s –
1. Eliminated large productions from Oahu Island
2. Papaya Industry relocated to Puna District
(free of PRSV)
1980s –
1. 95% production established in Puna
2. Research started on resistance through transgenic approach
1992 – PRSV spread to the Papaya fields in Puna
Small scale field trial with the transgenic lines
1998 –GM papaya commercialized
GM Papaya saves the industry!
Transformed papaya cell – expresses modified viral gene – allows the plant to recognize the virus when it enters
The virus is targeted for degradation, cannot multiplyResistant
Non-transformed papaya cell
Virus multiplies in plant cells and spreads through plant
Susceptible
The science behind
GE Crops with the Non-Browning trait
Why did scientists develop non-browning crops?
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Polyphenol oxidase which causes browning
For more information: https://nas-sites.org/ge-crops/category/pastevents/webinars/
Benefit to consumers – Reduce food waste
For more information: https://nas-sites.org/ge-crops/category/pastevents/webinars/
For more information: https://nas-sites.org/ge-crops/category/pastevents/webinars/
The science behind
Late Blight resistant potato
Why did scientists develop late blight resistant potatoes?
Cultivated and wild potatoes (photo: Peggy Greb)
Potato late blight resistant genes were found in wild potato species – But it is so hard to transfer to cultivated background!
- Crossing wild & cultivated potato gives sterile triploid (3X) potatoes
- Colchicine chemical is used to double chromosome number to get a fertile hexaploid (6X)
- Hexaploid when crossed to diploid wild potato gives tetraploid (4X) progeny
Cultivated (4X) Tetraploid
Wild (2X) Diploid
At every stage embryo rescue may be needed to go to the next step. Even so, you never know if the resistance gene from the wild potato ever got transferred to the cultivated (4X) after all that effort!
It is much more straightforward & efficient (less errors) to clone resistance genes from wild potato & genetically engineer it to the cultivated potato Cultivated and wild potatoes (photo: Peggy Greb)
Potato late blight resistant genes were found in wild potato species – But it is so hard to transfer to cultivated background!
So, the genes were isolated and cloned so they could be inserted into cultivated potato using Genetic Engineering techniques – to develop resistant varieties faster
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Plant Transformation Process – enabled the development of late blight resistant potatoes faster…
The late blight resistant varieties developed perform as expected in the laboratory, greenhouse and the field….
IF genetic engineering was not possible for potato, how can you breed for resistance to late blight?
Because potato is polyploid species, genetics is complicated and breeding varieties conventionally takes many many years! https://gmoanswers.com/infographic-how-does-gmo-get-market-gmo-regulation-review-and-research-process
What it takes to get a GMO to the market…
How many countries are there in the world? 195
Regulations ask: Are GMO crops and products safe for food, feed and the environment?
- Every country has Biosafety regulations to ensure the safety of biotech products for the environment, human and animal health and biodiversity
- US has a coordinated approach and uses the principle of substantial equivalence
Principle: If a transgenic food or organism can be shown to be substantially equivalent in composition to that of a conventional organism of the same kind, the modified organism and its products should be judged to be as safe for consumption as the conventional ones
When genes come from different sources, there are concerns
Laboratory Biosafety
Greenhouse Biosafety
Confined Field Trials
Application for
Release
General Release
Food imports
Institutional Biosafety Committees (IBCs)
National Biosafety Committees (NBCs)
Plant Quarantine Officers (PQs)
Without proper regulatory systems in place, GE research
cannot move beyond the laboratory and greenhouse
biosafety stages
Biosafety regulatory application process
- Each country has their own regulatory system to evaluate
safety of GE crops and products at every stage from
development to deployment
- 3 committees look into safety; IBCs, NBCs and PQs
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US Regulation of Biotech products uses a Coordinated framework (1986)
Environmental Protection
Agency (EPA)
Food and Drugs Administration
(FDA)
US Department of Agriculture
(USDA)
*This is an over-simplified version so that it is easy to understand
Animal Plant Health Inspection Service (USDA-APHIS)Safety assessment for cultivation, movement and/or importation
Office of Pesticide Programs for safety assessment of pesticides (including distribution and labels)
Center for food safety and applied nutrition for food safety and labeling
Each agency in the coordinated framework use laws already in place to regulate GE organisms and their products
• US Government Role: Ensure that Biotech products are safe for consumption and environmental release
• Government regulation aims for:
– Transparency (rulemaking process)
– Predictability
– Science-based process
– Risk-based approach
US Coordinated framework (1986)
What is a Risk-based approach?
• Fundamental premises on risk:
– Omnipresent (risk is everywhere)– Identifiable– Measurable (Risk = Hazard x Exposure)– Manageable– Proper management Safety
• Other points:– Accommodation (can GE crops co-exist with non GE
crops?)– Self regulation
Potential issues faced with GE crops are carefully assessed by regulatory agenciesEnvironmental Biosafety
Weediness/InvasivenessPollen/Gene flowEffect of novel toxins on non-target organismsDevelopment of pest resistanceOther agroecological and crop management issues (eg. secondary pest issues and mixed cropping)
Food SafetyWhether the food derived from transgenic crops is safe for humans and animals
Socioeconomic & Ethical
You will hear about these tomorrow…
An example of how Biotech products get regulated with the Coordinated framework (1986)
Non browning Arctic Apple
Bt maize resistant to insect pests
Virus resistant papaya
USDA-APHIS
US EPA US FDA
No pesticidal properties so, US EPA has no role in the regulation
USDA, EPA and FDA
Both Bt corn and virus resistant papaya have pesticidal properties so, all three agencies regulate the crop and product
For more information: http://www.farmindustrynews.com/seed/refresher-how-gmo-crops-get-approved
GMO labeling in the US
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“On July 29, 2016, President Barack Obama signed a bill into law requiring the labeling of food containing genetically modified ingredients, following a drawn-out battle between the food industry and pro-labeling groups on the issue”
For Michigan: http://michfb.wsoldev.com/MI/GMOLabeling/
Why would we want to have GE crops anyways?
• Climate change is going to adversely affect agriculture and human well-being especially in the developing world by:– Yield declines in most important crops – South Asia predicted
to be most hardly hit– Increasing prices for most important agricultural crops and
products
• Agricultural sector needs to have tools for speeding up the development of new and improved crops to deal with constraints related to climate change
• Genetic engineering is one such biotechnology tool available for the plant breeder to improve crops
Risk of banning GMOs… A 2016 study
• Goal: Contribute to the literature on the benefits of GMO technology by estimating the impacts on price, supply and welfare
• Food price impacts range from an increase of 0.27% to 2.2%, depending on the region.
• Total welfare losses associated with loss of GMO technology total up to $9.75 billion.
• Substantial increase in GHG emissions predicted if GMO technology is banned (By modeling land use change owing to the loss of GMO traits)
Even after 20 years of eating GMOs, still there are a lot of misconceptions.
Interesting video on Simplot potato from The Daily Show:
https://www.youtube.com/watch?v=zY-UPHLJ31A (6.17 mins)
Did you learn anything new about GMOs today? What was it?
Questions?