Plants and other GMOs: What's out there?

Now that we've covered what genetic engineering is (and isn't) and how it's done, we get down to the real meat of the issue: the organisms themselves.

Photo credit: Ks.mini, Wikimedia Commons

This is, by necessity, a very United States-centric post.  Being located in the U.S. myself, most of my
information is centered around GMOs here; in addition, it's still U.S. companies which are pushing most of the advances in the kinds of crops consumers in the Western world see on store shelves.  That's changing gradually, as more academic and governmental institutions in places like sub-Saharan Africa and southeast Asia take charge of modifying crops important to those areas.  The center of GMO advancement still lies in the United States, though, so that has most of my focus.

According to popular belief, all the plants we eat are GMOs unless they're labeled "organic".  In actual fact, however, only about two dozen plant species have been listed as having been genetically modified, and a handful of those have gone on to gain the approval and acreage necessary to enter our food supply.  A couple of those plants provide products which are used widely in processed food, but if you pick up a random item in your supermarket's produce section, the odds are very high that it's not a GMO.

So what plants have gotten modified so far?  Here's a list from the ISAAA, an industry organization with an interest in reporting the full extent of GMO advancements:¹

• Alfalfa (Medicago sativa)
• Apple (Malus x Domestica)
• Argentine Canola (Brassica napus)
• Bean (Phaseolus vulgaris)
• Carnation (Dianthus caryophyllus)
• Chicory (Cichorium intybus)
• Cotton (Gossypium hirsutum L.)
• Creeping Bentgrass (Agrostis stolonifera)
• Eggplant (Solanum melongena)
• Eucalyptus (Eucalyptus sp.)
• Flax (Linum usitatissumum L.)
• Maize (Zea mays L.)
• Melon (Cucumis melo)
• Papaya (Carica papaya)
• Petunia (Petunia hybrida)
• Plum (Prunus domestica)
• Polish canola (Brassica rapa)
• Poplar (Populus sp.)
• Potato (Solanum tuberosum L.)
• Rice (Oryza sativa L.)
• Rose (Rosa hybrida)
• Soybean (Glycine max L.)
• Squash (Cucurbita pepo)
• Sugar Beet (Beta vulgaris)
• Sugarcane (Saccharum sp)
• Sweet pepper (Capsicum annuum)
• Tobacco (Nicotiana tabacum L.)
• Tomato (Lycopersicon esculentum)
• Wheat (Triticum aestivum)

I've put in italics the crops which don't produce food for humans.  Of the remaining 19, only the 10 in bold are currently being grown for commercial use (some others, like beans, have approval but no one grows them at this point).²  The three crops which I've underlined are maize (corn), cotton, and soybeans -- these three crops make up the vast majority of GMO acres in the United States.  Correspondingly, almost all of the yield of those three is GMO: 90% of cotton, 90% of corn, and 93% of soybeans grown in the U.S. were GMO in 2013, and the trend has been upward.³

Corn and soy are used in a lot of foods; think about how many times you see items like high fructose corn syrup and soybean oil on food labels. The current rules for the North American and European organic certification agencies exclude GMOs, but unless the ingredient is listed as organic, there's a very high probability that the ingredients derived from corn or soy are going to come from GMOs.⁴

Future crops could include bananas⁵ and oranges⁶, and cassava⁷ in Africa (where it is a significant source of food).  Wheat has been in development for some time by various sources. Several kinds of rice have been developed and even approved, but aren't currently on the market.³  And in the research world, modifications to both tobacco and garden cress (Arabidopsis thaliana) have become routine.

In addition to plants, several other organisms have been the focus of genetic modification.  A variety of salmon has recently been approved in the U.S., but it remains the only animal to have that distinction.⁸  There are a great many single-celled GMOs, however, most of which get far less press than plants and salmon.  Escherichia coli is probably the leading contender here, as a bacterium which is used to produce an enormous number of substances; the variety of E. coli being used is not the one you hear about in connection with food-poisoning reports, being harmless to humans.⁹  It shares its cousin's talent for multiplying rapidly, and it's easily modified, making it ideal for genetic work.

Substances produced with GM E. coli include:

• rBST, the hormone given to dairy cows to improve milk production.¹⁰
• Interferon, used to treat multiple sclerosis and certain types of cancer.¹¹
• Some vaccines which use isolated genetic material rather than whole cells.¹²
• Human growth hormone (hGH), used to treat dwarfism and a few other disorders.¹³

Another rapidly-multiplying organism is yeast, the same kind found in bread and beer.  It's widely used to make synthetic insulin.¹⁴

Some substances require fancy transcription and folding operations which are normally performed by human cells, and the best way to mimic that is to use something similar.  The most common stand-ins are Chinese hamster ovary (CHO) cells, which can be grown in cultures and modified to produce things which E. coli hasn't been coaxed into making.  Some things currently made with this method are follicle stimulating hormone (FSH), an important part of ovarian function and human fertility;¹⁵ human blood clotting factors, used to treat hemophiliacs and those with similar problems;¹⁶ and tissue plasminogen activator (tPA), which thins the blood in stroke victims.¹⁷  In recent years, tPA has been successfully produced in E. coli,¹⁸ which may be more common in the future -- and it's also been produced in cucumber plants, in a demonstration of the possible future of pharmacology.¹⁹

Antibodies are commonly made using various types of cells which have been modified, including bacterial, mammalian, and fungal.²⁰  Some animal vaccines are created from pathogens which have been de-fanged by removing a couple of their dangerous genes, making them harmless; these include rabies and Salmonella vaccines.²¹

The field of GMOs is both narrower and more diverse than what the popular press might lead you to believe; many important medicinal products are made using GMOs, just not the plants growing in the field that we all think about.  There has been some investigation into combining those two uses, however, creating fast-growing plants which can make drugs or hormones by the acre, ready to be purified and distributed cheaply.  That kind of application is still only found in laboratories, but it may only be a matter of time before it reaches the real world.

Now that you know which organisms are out there, it's time to dive into how they're different: what genes have been added to them, and why.  That's the next segment.  Stay tuned.

[This article is part of the series on GMOs. Jump to the first post for an overview and index.]





¹ The International Service for the Acquisition of Agri-biotech Acquisitions GMO Crops List, retrieved 18 January 2016
² GMO Compass modified plants list, various entries, retrieved 18 January 2016
³ Fernandez-Cornejo, Jorge, Seth Wechsler, Mike Livingston, and Lorraine Mitchell. Genetically Engineered Crops in the United States, ERR-162 U.S. Department of Agriculture, Economic Research Service, February 2014.
⁴ USDA: Organic 101: Can GMOs Be Used in Organic Products? retrieved 18 January 2016
⁵ Shekhawat, Upendra K. S., Siddhesh B. Ghag and Thumballi R. Ganapathi. Transgenic Approaches for Development of Disease Resistance in Banana. Bhabha Atomic Research Centre Newsletter, Issue 337, March-April 2014, pp 18-23. Retrieved January 18, 2016.
⁶ Harmon, Amy. "A Race to Save the Orange by Altering Its DNA". The New York Times, July 27, 2013.
⁷ Zhang P, Vanderschuren H, Fütterer J, Gruissem W. Resistance to cassava mosaic disease in transgenic cassava expressing antisense RNAs targeting virus replication genes. Plant Biotechnol J. 2005 Jul;3(4):385-97.
⁸ USFDA. FDA Has Determined That the AquAdvantage Salmon is as Safe to Eat as Non-GE Salmon. Retrieved 18 January, 2016
⁹ Dale, Jeremy W. and Malcolm von Schantz. From Genes to Genomes: Concepts and Applications of DNA Technology. John Wiley & Sons, Mar 11, 2008.
¹⁰ Iowa State University - University Extension. Bovine somatotropin (bST). North Central Regional Extension Publication, Biotechnology Information Series (Bio-3), December 1993.
¹¹ Babaeipour V, Shojaosadati SA, Maghsoudi N. Maximizing Production of Human Interferon-γ in HCDC of Recombinant E. coli. Iran J Pharm Res. 2013 Summer;12(3):563-72.
¹² Nascimento, I.P. and L.C.C. Leite. Recombinant vaccines and the development of new vaccine strategies. Braz J Med Biol Res. 2012 Dec; 45(12): 1102–1111.
¹³ Rezaei, M., & Zarkesh-Esfahani, S. H. (2012). Optimization of production of recombinant human growth hormone in Escherichia coli. Journal of Research in Medical Sciences: The Official Journal of Isfahan University of Medical Sciences, 17(7), 681–685.
¹⁴ Nielsen, J. (2013). Production of biopharmaceutical proteins by yeast: Advances through metabolic engineering. Bioengineered, 4(4), 207–211. http://doi.org/10.4161/bioe.22856
¹⁵ Fauser, Bart C.J.M. (1998). "Developments in human recombinant follicle stimulating hormone technology: are we going in the right direction?" Human Reproduction Volume 13, Supplement 3; retrieved January 18, 2016
¹⁶ Kaufmant, Randal J., Louise C. Wasley, Barbara C. Furie, Bruce Furie, and
Charles B. Shoemaker (1986). Expression, Purification, and Characterization of Recombinant γ-Carboxylated Factor IX Synthesized in Chinese Hamster Ovary Cells. The Journal of Biological Chemistry, 261, 9622-9628.
¹⁷ Vergara, Mauricio et al. Simultaneous environmental manipulations in semi-perfusion cultures of CHO cells producing rh-tPA. Electron. J. Biotechnol. [online]. 2012, vol.15, n.6, pp. 2-2. ISSN 0717-3458.
¹⁸ Majidzadeh-A, K., Mahboudi, F., Hemayatkar, M., Davami, F., Barkhordary, F., Adeli, A., … Khalaj, V. (2010). Human Tissue Plasminogen Activator Expression in Escherichia coli using Cytoplasmic and Periplasmic Cumulative Power. Avicenna Journal of Medical Biotechnology, 2(3), 131–136.
¹⁹ Asgari M, Javaran MJ, Moieni A, Masoumiasl A, Abdolinasab M. Production of human tissue plasminogen activator (tPA) in Cucumis sativus. Prep Biochem Biotechnol. 2014;44(2):182-92
²⁰ Siegel DL. Recombinant monoclonal antibody technology. Transfus Clin Biol. 2002 Jan;9(1):15-22.
²¹ Council for Agricultural Science and Technology. Vaccine Development Using Recombinant
DNA Technology Issue Paper Number 38,May 2008. Retrieved January 18, 2016.