GMO Foods - Friend or Frankenfoe Or, how I stopped worrying about minor stuff and learned to love science. Stuart L. Kaplan

What are “GMOs”? “Genetically modified organisms” Also, organisms modified genetically through transgenic biology For further reading, I suggest… http://gmo.geneticliteracyproject.org/FAQ/what-are-gmos/ What?? OK - let’s start a bit further back

What are “genes”? Fundamental units of inheritance. Simple example: Eye color in people. Brown-eyed mother, brown-eyed father, child born with blue eyes. How is this possible? Punnett square.

How do genes work? Genes are made of DNA DNA is a double helix. Think of it as a (twisted) ladder but with the rungs consisting of a pair of matched up molecules.

All Enzymes are Proteins Enzymes do the “work” of the cell, the tissue and the organism. Altering genes or genotype alters enzymes. Altering enzymes can impact phenotype.

Altering genes purposefully In order to produce desirable phenotypes. Humanity has been doing this for thousands of years. Integral part of agriculture. Medical advancements in the future (i.e., “gene therapy”)?

How do we alter genotypes? Animal and plant breeding. Selecting for random but useful mutations. Shattering resistance in cereal grains, pulses. Combining parents expressing useful traits in order to produce offspring with even greater expression of useful traits. Increased grain yield. Increased resistance to disease Improved stalk strength Increased production of milk, wool, meat, etc.

“Conventional” plant (and animal) breeding depends on: Finding and then cross-breeding parent stock (“lines”) that contain desirable traits. Produces a large population of offspring that represent a wide array of genetic outcomes. Then find the desirable phenotype(s) among the thousands produced and across many environments.

The parental lines may come with many undesirable traits. For example, looking for disease resistance in “wild” populations of the same species. These lines commonly contribute undesirable traits to offspring which then have to be identified and removed from the population. Expensive, imperfect, inefficient.

How do GMOs fit into this? Identifying useful genes in other organisms for inclusion in the genotype of the crop in need of improvement. This is the origin of the term “transgenic”. Using molecular biological techniques to move those genes discretely from the source organism to the host. Select for the offspring that displays the new phenotype.

Example: “Insect Resistance in Corn” Bacillus thuringiensis (“Bt”) is a soil bacterium that has been used for years by farmers (primarily “organic” farmers) in killing certain insect pests (https://en.wikipedia.org/wiki/Bacillus_thuringiensis ) The commercial formulation of Bt used by these farmers is “Dipel” (https://www.valent.com/agriculture/products/dipel/)

Monsanto was able to move the genes responsible for the production of the toxic component from the Bt bacillus into corn plants. They were further able to control where the genes would express in the corn plant. Thus, “Bt corn” Significant reduction in application of insecticides to corn. Higher grain yields. Still effective after several decades of use.

Example: “Herbicide Resistance in Corn” (a misnomer!) Glyphosate was a herbicide developed by Monsanto and sold under the name “Roundup” (https://en.wikipedia.org/wiki/Glyphosate). It was non-selective and had no soil activity (i.e., it killed only those plants whose aboveground tissue was sprayed with the herbicide). The most important herbicides in use on row crops (e.g., corn, soybeans, cotton, etc.) were selective at the time and many had soil activity. Thus, Roundup had limited utility in crop production.

Glyphosate interferes with the biochemical pathway necessary for the synthesis of the amino acids phenylalanine, tyrosine and tryptophan. This pathway is not present in animals, which instead obtain these essential amino acids from their diets. Glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS).

Monsanto found a strain of Agrobacterium whose EPSPS was not inhibited by glyphosate. Agrobacterium tumefaciens is a bacterium that cause “crown gall” in host plants by transferring DNA between itself and host plants (https://en.wikipedia.org/wiki/Agrobacterium). Monsanto was able to insert the responsible Agrobacterium gene into corn and other crop plants, thus rendering them immune to the toxic effects of glyphosate.

Roundup resistance (“Roundup Ready”) provided for superior weed control with greater convenience for the grower for many years. Glyphosate resistance is now a common occurrence that the industry has to deal with. Unsurprising. “Superweeds”? Another misnomer.

Other Examples: “Golden Rice” Rice with elevated levels of Vitamin A https://en.wikipedia.org/wiki/Golden_rice https://www.washingtonpost.com/news/speaking-of-science/wp/2016/06/29/more-than-100-nobel-laureates-take-on-greenpeace-over-gmo-stance/ Resistance to “Banana Xanthomonas Wilt (BXW)” https://en.wikipedia.org/wiki/Banana_Xanthomonas_wilt https://www.geneticliteracyproject.org/2015/05/05/documentarian-scott-hamilton-kennedy-explores-why-activists-block-gmo-solution-to-african-banana-wilt-crisis/

What does it take to get a GMO approved? Time and money For further detail: http://gmo.geneticliteracyproject.org/FAQ/what-does-it-take-to-bring-a-new-gm-product-to-market/ 13 years and $135 million.

Suggested reading http://theconversation.com/not-all-gmo-plants-are-created-equally-its-the-trait-not-the-method-thats-important-39532 http://theconversation.com/moving-beyond-pro-con-debates-over-genetically-engineered-crops-59564 http://www.nytimes.com/interactive/2016/07/12/science/gmo-misconceptions.html?_r=0 https://www.geneticliteracyproject.org/2016/05/10/d-day-approaches-ugandas-biosafety-law-pave-way-gmo-crops/ http://www.vox.com/2016/5/18/11690992/gmos-review-evidence-safety-health