Monday, February 11Loss of Genetic Diversity in the Late 20th Century •Crops: open pollinated (naturally grown) vs. hybrid •Hybrids do not breed true.•Two genetic lines are crossed to make a hybrid crop. However, when the crop is planted the next year, the crop becomes more of a mixture with diversity from both crops. •Pollinated, or pure, varieties, do not change each year.•There are biological, political, and economic questions behind using hybrid plants. Restricted Genetic Base of Crops•Most corn grown in the U.S. comes from about 8 genetic lines.•This makes crops vulnerable.•Corn blight of the 1970sFOOD ISSUES: GENETIC ENGINEERING OF CROPSWhat Is a GMO or GM Food?•GMO = Genetically Modified Organism•GM Food = Genetically Modified Food•Organism containing DNA altered through genetic engineering techniques•Transfer of DNA is possible between species, genera, or kingdoms•Natural foods do not do this. It’s the result of human intervention.Traits Developed by Genetic Engineering•abiotic stress tolerance•disease resistance•herbicide tolerance•insect resistance•modified product quality•pollination control system•pharmaceutical delivery Methods for Transforming Crops•1. mediated plant transformation (agrobacterium)*•2. chemically mediated introduction into protoplasts and regeneration•3. direct DNA transfer system•4. electroporation•5. conventional breeding - cross hybridization and selection involving transgenic donor(s)*•6. micriparticle bombardment of plant cells or tissue*•7. pollen-tube pathway (PTP)•*methods we will study in classAgrobacterium - Mediated Plant Transformation•For a detailed explanation, refer to diagrams on slides on ELC. There won’t be test questions on the details of this process.Microparticle Bombardment of Plant Cells or Tissue•1. Tiny particles of gold or tungsten are coated with DNA.•2. Accelerate particles to very high velocities using helium (chamber held partial vacuum).•3. DNA-coated microparticles pass through a disk into a dish containing target tissue or cells. Traits Developed by Genetic Engineering in Plants•abiotic stress tolerance•drought tolerance•disease resistance •viral diseases (papaya, squash)•herbicide tolerance•glyphosate tolerance (Roundup)•insect resistance•The idea is that with GMOs, less pesticides will be needed. •cotton and corn pests•modified product quality•high lysine corn•golden rice - increased vitamin A•digestibility of canola seed by chickens and pigs•delayed ripening of melons •high monounsaturated oleic acids (soybean)•pollination control systemCriticism of GM•development of resistance (insects or weeds)•gene transfer into non-target organisms•weeds•non-GM cultivators•health impacts?•restricted genetic base of crops•patenting on life formsPlant Video•During the process of natural selection, the weeds that survived the Roundup kept multiplying and spread over entire farms.Development of Resistance (Insects)•Bt cotton and Bt corn - 400 million acres planted worldwide since 1996•“one of the largest selections for insect resistance ever known”•To delay resistance, non-Bt crops are planted near Bt crops to provide “refuges” for susceptible pests.•Bt-resistant populations of bollworm were found in more than a dozen cotton fields in Mississippi and Arkansas between 2003 and 2006.•Bt-resistant populations of Western corn rootworm were found in several cornfields in Iowa in 2009.•In China, resistance was conferred by two unrelated, dominant mutations in the field populations. They are difficult to manage and not readily slowed using refuges. •It became a dominant trait. Gene Transfer into Non-Target Organisms - Weeds•GM plants could cross with wild relatives. If these wild plants are weedy, they might neednew types of chemical control.•Example: Canola and related wild radish•In 2012, 88% of U.S. corn was GMO•Corn easily cross-pollinates with nearby plants.•Genes from genetically modified crops can drift or “trespass” into non-GMO fields.•Most organic corn in the U.S. contains 0.5%-2% GMO material, according to companies that sell corn to organic dairies or poultry farmers.GM Crops Risk Assessment - Health•Some of the most popular U.S. GM crops (corn, soybeans, canola) have been staple ingredients for years in virtually every type of packaged food, from soup and tofu to breakfast cereals and chips.•Proposition 37 from California (November 2012 ballot) •require all food manufacturers to appropriately label all food, raw and processed, that contains ingredients made from