I. I.Genetic Engineering C. C.Advantages 1. 1.Greater agricultural yields More food production per acre could Reduce area needed to support existing population.

I. Genetic Engineering

C. Advantages1. Greater agricultural yields

• More food production per acre could• Reduce area needed to support existing population• Support future population growth

• Ex – European corn borer destroys 7% of annual corn harvest worldwide• Modified corn resistant to ECB could eliminate this loss• Extra corn = 7-10 mmt (enough to feed 60 million people)

2. Reduced herbicide use• Wheat, corn, soybeans, cotton, sugar beets, alfalfa, etc. engineered to be

resistant to certain herbicides (e.g. Roundup)• Farmers can spray crops with less herbicide to kill weeds• Ex – Soybeans – Reduction of pesticide use by 10-40% from 1996-1997

3. Reduced pesticide use• Crop plants can be engineered for resistance to certain pesticides• Ex – Insect resistant cotton planted in Alabama led to an 80% reduction

in use of insecticides on cotton from 1996-19974. Environmentally beneficial tasks

• Ex – Bacteria engineered to degrade petroleum rapidly can be used to clean up oil spills

5. Novel properties• Ex – Phytase maize (approved in China, 2009)

• Enzyme makes phosphorus more available to livestock• Enhances animal growth, reduces P content of waste (up to 60%)

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

Huang et al. 2002 Nature 418, 678-684

Genetically modified crop traits testedin developed countries, 1987–2000

I. Genetic Engineering

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

(acreage basis)• 2011: corn 88%, cotton 90%, soy 94% GM• Other major growers of GM crops

1) Brazil

2) Argentina

3) India

4) Canada

5) China

http://www.ers.usda.gov/Data/BiotechCrops/genengcrops.gif

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