Research Scientists Advocating the Use of Bt Corn Dr. Hilda Castillo Dr. Carol Tolley University of Gattica

Historical Plant Breeding Programs Incorporation of genes Crossbreeding Wild species into common cultivars Introgression Time consideration Cost Effectiveness From The National Agricultural Biotechnology Council Report 2001

Plant Breeding Goals Genetic modification to gain Higher yields Nutritional values Environmentally compatible production Reduced pesticide use Herbicide tolerance Reduced energy use Longer shelf life

Biotechnology and Genetic Engineering Genetic modification Built in protection from pests Selection of single known gene Precise Cost effective

Bacillus thuringiensis Naturally occurring bacteria Known biopesticide Used for 50+ years Predictable effects

Delivery of new genes - Vector Ti plasmid Agrobacterium tumefaciens Remove DNA Insert Bt gene Introduce in plant Picture from Strickberger, (1991) Genetics

Benefit of Bt corn Reliable control of target pest Reduced crop loss Estimated $1.2 billion/year in U.S. Reduced pesticide use Increased yields Healthier Reduced fumonisin mycotoxin levels Utilization of marginal land

U.S. Regulatory Policy EPA – regulates plants with pest protection USDA – imposes regulations during development FDA – approves new food safety

Bt Transgenic Plants. Annu. Rev. Entomol. 47:845-81 In Conclusion Pest population reduction affects the overall biological community whether using: Bt plants, biological control agents, resistant plants, insecticides, cultivation techniques, or any other method to control pest As with any technology, Bt plants were incorporated without complete understanding of their effects but with a certainty that the risks would be fewer than current technology and that the benefits of GE crops would be greater. Shelton, A.M. et al. (2002). Economic, Ecological, Food Safety, and Social Consequences of the Development of Bt Transgenic Plants. Annu. Rev. Entomol. 47:845-81

Extra Slides

Bacillus thuringiensis Isolated in Japan in 1915 Insecticide commercialized in 1930 1995 – 182 Bt products marketed Known entity Several strains used in Bt corn Cry1, Cry 2, Cry 3, Cry9

Corn Fungi Naturally occurring fungi Edible and non-edible Point of entry Through roots Areas of water collection damage to ears via Lepidoptera feeding Fusarium moniliforme (and other species)

Mycotoxins Fusarium moniliforme Mycotoxins produced Adverse health effect in livestock Possible carcinogen Occurrence High in Raw Corn Less in processed corn Very reduced in Bt corn

What Can You Get From a Bushel of Corn? A typical bushel of corn weighs 56 pounds and contains approximately 72,800 kernels. Most of the weight is the starch, oil, protein and fiber, with some natural moisture. What can be extracted from a bushel of corn? 32 Pounds of Starch OR 33 Pounds of Sweetener OR 2.5 Gallons of Fuel Ethanol AND 11.4 Pounds of 20% Gluten Feed AND 3 Pounds of 60% Gluten Meal AND 1.6 Pounds of Corn Oil ©Copyright 2001 Ohio Corn Marketing Program.

Wild Relatives From genetic origin Potential outcrossing Mexico Central America South America Potential outcrossing Influence continued evolution

Land Races Grown and selected for generations Found world wide May have developed resistance to specific pests Selected for specific growing regions Potential outcrossing with cultivars

Problems Loss of genetic variability Through outcrossing Loss of habitat of wild species Planting instead of land races Influence on potential evolution

Outcrossing Gene capture and expression Wild, weedy relatives Mexico Teosinte Effort to reduce outcrossing

Weed potential 10 year study Britain Rape, corn, sugar beet Conclusion – not invasive

Horizontal gene transfer Through Crop residue Pollen Root exudates Dependent on soil characteristics 1.6 to 22 days As long as 46 days As stable DNA – months to years

Soil organisms EPA evaluated Birds Fish Honeybees Ladybugs Parasitic wasps Lacewings Springtails Aquatic invertebrates

Pollen Bt is expressed Heavy Wind dispersed Limited movement

Agricultural GM Crops Widely used Accepted No proven detrimental effects Increased yields without increased pesticide use From: Biotechnology Industry Organization http://www.bio.org/er/agriculture.asp