I. Genetic Engineering

D. Drawbacks• Opponents emphasize failures of

technology, potential environmental harm• “Frankenfood”• “Farmageddon”1. Harm to native species through competition

• Transgenic organisms could be superior competitors• Potential route to extinction for native species

2. Damage to beneficial insects• Ex – Evidence that ladybugs and lacewings suffer (shorter lifespan,

reduced reproduction) when fed aphids and caterpillars that had fed on GM potatoes and corn, respectively

3. Damage to soil community• Certain GM crops could reduce activity of soil fungi and microbes• Negative impact on nutrient cycling in the soil

4. Release of resistance genes• Could potentially lead to “super weeds” if resistance genes get

transferred to weedy species• Could harm non-GM agriculture, including organic farming through

pollen drift5. Upset natural balance of ecosystems

• Could result from release of GMOs or hybridization between GMOs and native species

• Ex – GM rape can crossbreed with wild turnips, passing herbicide tolerance to offspring

• Potential solution = “Terminator technology”

I. Genetic Engineering

E. Trends• 125 GM agricultural plants approved for

growth in the U.S. (ISAAA)• Most designed to

1) Reduce pest damage

2) Confer resistance to herbicides, pesticides, viruses, other pathogens

3) Reduce crop spoilage

Genetically modified crop traits testedin developed countries, 1987–2000

I. Genetic Engineering

E. Trends• US grows ~48% of GM crops worldwide

(acreage basis)• 2012: corn 88%, cotton 94%, soy 93% GM• Other major growers of GM crops

1) Brazil

2) Argentina

3) India

4) Canada

5) China

www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us/recent-trends-in-ge-adoption.aspx

I. Genetic Engineering

F. Examples1. Bollgard® and Bollgard II® Cotton

• Both strains express insecticidal protein isolated from Bacillus thuringiensis (Bt)

• Safe – Farmers can spray with Bt toxin and still label produce as organic

• Low toxicity to most non-target organism types• Low persistence – breaks down readily

• Bollgard II® has stacked traits to enhance effectiveness• Controls bollworms, budworm

• Year 2000 – United States averages• Cotton fields planted with Bollgard ® sprayed 3.9

times less often vs. conventional fields• Reduced total pesticide use by 2.7 million pounds• Pest control cost less - $15.43/acre

• Higher production - 37 pounds/acreI. Higher profit - $39.86/acre

• Concern – Development of resistance by insect pests

I. Genetic Engineering

F. Examples2. Golden Rice

• GM rice containing genes that produce beta-carotene• Can be converted to vitamin A• Vitamin A deficiency (VAD) may cause weakened immune

systems, partial to total blindness, and increased chance of death

• VAD causes 350,000 cases of blindness and has been linked to 1 million+ deaths each year

• Highly controversiala. Proponents

• Reduce incidence of blindness and other VAD related health disorders

• 1/2 lb of rice/day will keep VAD symptoms awayb. Opponents

• Nutritional deficiencies will prevent people from absorbing beta-carotene from rice

• Concentrations of beta-carotene in rice are low, and an average woman would need to eat 16 lbs of golden rice a day to get 100% of daily requirement

• Alternatives like leafy green vegetables or unpolished rice are better, cheaper sources of vitamin A

• Western corporations are trying to control rice production

I. Genetic Engineering

F. Examples3. Future GM crops

• SmartStaxTM corn• Pest resistant, herbicide tolerant

• Bt rice• Pest resistant

• High omega-3 soybeans• Enhanced nutrition

• RR Sugarbeets*• Herbicide tolerant• 2007: <10% of US• 2009: 95% of US

• Blue roses• Ornamental

I. Genetic Engineering

G. Benefits and Risks1. Benefits

• Accelerated improvement of crop strains

a. Elevated yields, either per plant or per acre• Usually involves inserting growth factor• Plants grow larger, faster or both• Con – Accelerated growth may alter chemical

composition Allergies, digestive problems, etc.

b. Accelerated maturation process• Increased yield per acre, more crops per year• Con – Plants produce different compounds at

different life stages• Young plants tend to produce more irritants and

toxins (self defense)• Potential to cause digestive or allergic problems

I. Genetic Engineering

G. Benefits and Risks1. Benefits

c. Increased resistance to disease, pests, toxins• Reduced losses Greater yield• Reduced application of chemicals• Con – Potential transfer of resistance genes to

weedy plant species through pollination• Less problematic in areas where crop plants don’t

have wild relatives• Con – Development of resistance in pests

d. Increased longevity of harvested produce• Resistance to spoilage• Ex – Potato engineered with bacterial gene for

antifungal properties• Helps potatoes to stay in storage without rotting• Con – Chemicals that resist decomposition likely to

be more difficult to digest

I. Genetic Engineering

G. Benefits and Risks1. Benefits

e. Increased resistance to cultural extremes• Ex – Insertion of Arctic flounder antifreeze protein

genes into strawberry• Confers greater frost resistance and better fruit

storage properties• Con – Potential transfer of antifreeze genes to weedy

plant speciesf. Increased nutritional value

• Ex – High starch potato that absorbs less oil when cooking (low fat potato chips)

• Ex – Canola oil (Laurical®) with healthier composition• Con – Unknown effects of eating modified foods• Ex – Insertion of Brazil nut gene into soybeans to

increase protein content• Many people allergic to Brazil nuts

I. Genetic Engineering

G. Benefits and Risks1. Benefits

g. Reduced dependence on chemical fertilizers• More efficient growth lower use of fertilizer• American farmers spend >$12 billion a year on

chemical fertilizers• 50% or more of fertilizer applied to crops is not

absorbed and enters runoff water pollution• Con – Transfer of genes for greater growth

efficiency to weeds could be disastrous• Con – Substitution of dependence on big

western agribusiness

I. Genetic Engineering

G. Benefits and Risks2. Risks

a. Unexpected effects• May or may not be beneficial• Ex – Klebsiella planticola (soil bacterium) engineered

to transform plant residue into ethyl alcohol (fuel)• GM strain in soils produced EtOH, leading to

poisoning of grasses and decrease in populations of beneficial mycorrhizal fungi

• Ex – Pseudomonas putida (bacterium) engineered to degrade 2,4-D (herbicide)

• Breakdown products highly toxic to fungi, including mycorrhizae

• Ex – Bacillus thuringiensis (Bt) toxin may bind to soil particles, slowing degradation and maintaining toxicity for longer than expected