W E Dyer PS 102 Risk Benefit Ratio Risks 4 1 5 2 3 6 Benefits 1 2 3 4 5 6 Q What basic biological fact underlies all of biotechnology A Before 2013 Genetically Modified GM Genetically Engineered GE Transgenic After 2013 Gene editing CRISPR is not transgenic Image courtesy of the U S Dept of Energy Human Genome Program The Central Dogma DNA mRNA Library An Analogy Blueprint The goal of biotech is to Protein Enzyme Image from Purves et al Life The Science of Biology 4th Edition by Sinauer Associates www sinauer com and WH Freeman www whfreeman com Tool How do they put the transgene into the plant Transgene Protein enzyme Promoter transcription factors bind here when where how much Crown Gall Caused by Agrobacterium tumefaciens The bacteria transfers The bacterial DNA can be replaced with a desirable gene Gene Gun Coat DNA onto micron size gold particles Blast particles into leaf pieces Some of the DNA will be incorporated Conventional plant breeding teosinte X Variety A Variety B Biotechnology Transgene New variety corn Who regulates GM crops US Dept of Agriculture USDA greenhouse and field studies ecological safety assessments US Environmental Protection Agency EPA environmental safety toxicology studies food tolerances experimental use permits product registration food safety Current and future GM GE crops In production starting in 1996 Crop Corn Soybean Cotton Canola Alfalfa Papaya Squash Apple Potato Sugar Beet Trait Herbicide resistance Insect resistance Virus resistance High fructose corn syrup Modified oil content Modified flower color Delayed browning Drought tolerance High fructose corn syrup Low acrylamide Approved but not yet in widespread production Crop Bean plum potato sweet pepper Chicory flax forage grass Eucalyptus Trait Virus resistance Herbicide resistance Altered growth But the development of CRISPR in 2013 changed the whole scenario CRISPR stands for clustered regularly interspaced short palindromic repeats and edits genes using a more complicated version of restriction enzymes CRISPR can reduce or remove a normal plant gene or it can modify existing gene expression patterns by altering transcription factor s CRISPR gene editing is not considered to be transgenic and so is not subject to any regulations George Retseck Wikimedia Commons CRISPR has already been used in the laboratory to alter wheat corn and fruit crops and a few are on the market now In the meantime let s examine the pros and cons of GM crops Possible advantages of GM crops reduced pesticide Produce inputs maybe less fertilizer Simpler crop production schemes for farmers More sustainable more efficient use of existing farmland preserves biodiversity Better able to grow under saline soil heat cold tolerance poor soil Help reduce food shortages in developing countries Produce more nutritious and safer food better canola oil high starch potato Golden Rice Produce cheaper A Case Study Roundup Ready Crops Roundup glyphosate is a that kills all plant species Roundup It does not persist in soil or leach into A gene for resistance has been put into soybeans corn and other crops Roundup Resistance Aromatic The normal situation A resistant enzyme Do conventional farmers like it Concerns About GM Crops Unnatural technology Encourages farmer dependence on Human health damage unregulated food pesticide residues allergies etc Environmental concerns superweeds ecological disasters loss of biodiversity gene flow Allows creation of biotech company monopolies and global domination Environmental Concerns 1 Do Bt crops kill Monarch butterflies 2 Will transgenes be transferred from crops to weedy relatives 3 Will the use of GM crops cause an increase in resistant pests Bacillus thuringiensis Bt that makes a protein toxic to certain insects sold as DIPEL for 40 years Bt proteins are nontoxic to fish mammals and other nontarget organisms have been inserted into cotton corn potato and other crops The plant makes the resistant to insect pests and so is Colorado potato beetle Cotton boll worm European corn borer Corn rootworm feeding damage Bt crops are very effective Monarch butterfly Danaus plexippus milkweed Asclepias curassavica Nature 399 214 1999 Macmillan Publishers Ltd Transgenic pollen harms monarch larvae JOHN E LOSEY LINDA S RAYOR MAUREEN E CARTER Department of Entomology Comstock Hall Cornell University Ithaca New York 14853 USA e mail jel27 cornell edu Although plants transformed with genetic material from the bacterium Bacillus thuringiensis Bt are generally thought to have negligible impact on non target organisms Bt corn plants might represent a risk because most hybrids express the Bt toxin in pollen and corn pollen is dispersed over at least 60 metres by wind Corn pollen is deposited on other plants near corn fields and can be ingested by the non target organisms that consume these plants In a laboratory assay we found that larvae of the monarch butterfly Danaus plexippus reared on milkweed leaves dusted with pollen from Bt corn ate less grew more slowly and suffered higher mortality than larvae reared on leaves dusted with untransformed corn pollen or on leaves without pollen Pollen for our assay was collected from N4640 Bt corn and an unrelated untransformed hybrid and was applied by gently tapping a spatula of pollen over milkweed Asclepias curassavica leaves that had been lightly misted with water Pollen density was set to visually match densities on milkweed leaves collected from corn fields Petioles of individual leaves were placed in water filled tubes that were taped into plastic boxes Five three day old monarch larvae from our captive colony were placed on each leaf and each treatment was replicated five times Milkweed leaf consumption monarch larval survival and final larval weight were recorded over four days Risk Analysis Is it possible to quantify risk Risk Toxicity can be estimated from or other experimentally determined values Exposure can be calculated from field studies LD50 Expressed in mg per kg of body weight Compound Sugar Salt Caffeine Cyanide Gasoline Aflatoxin LD50 rat 29 700 3 000 192 6 2 0 5 Roundup 5 000 6 000 Bt toxin LD50 average human A pinch One drop 1 pint Do Bt crops kill Monarch butterflies Six papers in the Proceedings of the National Academy of Sciences USA September 14 2001 Our best estimate is that less than 0 01 1 in 10 000 Monarch caterpillars are at risk for a negative effect from Bt corn pollen Where do GM crops go in the food chain Flour Sweeteners Oil