Genetically Modified Organisms in Agriculture – Papaya in Hawaii?
In February 2016, a study was published by Purdue University following an analysis of genetically modified crops (GMOs) in the global agriculture industry. They found that, “18 million farmers in 28 countries planted about 181 million hectares of GMO crops in 2014, with about 40 percent of that in the United States.” (Wallheimer). In 2015, for the first time since commercially grown GMOs entered the food chain, the global acreage decreased by a mere 2 million hectares. While this certainly does not represent a peak for the GMO industry, it may be the start of a plateau. To put things in perspective, the initial planting of commercial GMOs first occurred in 1996 with 1.7 million hectares. Over the past two decades, the global acreage has increased 100-fold. Thus, these biotech plants are said to be the fastest adopted crop technology in the history of modern agriculture (ISAAA.org). The manipulation of genetic material in crops is not a new phenomenon however.
Selective breeding is a technique that humans have been using on plants and animals since early prehistory. It is the process of “selecting two parents that have beneficial phenotypic – or physical – traits to reproduce, yielding offspring with those desired traits” (Selective Breeding or Artificial Selection). The practice has given rise to all kinds of crop and livestock varieties tailored to the whim of the breeder. This directed crossing of genetic material can take generations to succeed and is prone to unforeseen incompatibilities due to the somewhat random nature of inheritance in sexually propagated offspring. Genetic engineering; however, can overcome many of these issues. The science involves extracting specific fragments of DNA from one or more organisms and combining it with the DNA of another. This way, a single gene could be introduced into an already elite breed of plant or animal. A great way to illustrate this concept is with the outbreak of papaya ringspot virus that riddled the industry from 1950 until the early 2000s.
Papaya ringspot virus (PRSV) is one of the more harmful plant diseases to have affected modern agriculture. It was first discovered in the 1940s and by the ‘90s, it was said to be present in every papaya
producing region of the world. Production dropped by as much as 50% in some areas due to widespread susceptibility among commercial strains (How GM Papaya Saved Hawaii’s Papaya Industry). Resistance genes in papaya simply hadn’t been identified, cultivated, and were therefore unavailable. For this reason, the Hawaiian Department of Agriculture sought to develop a breed of GMO papaya. The plan succeeded when scientists extracted a cucumber gene responsible for resistance to cucumber mosaic virus, and successfully assimilated it into papaya. The coat protein provided by this gene protected the papaya varieties from such virulence. To this day, 70% of papaya acreage in Hawaii is composed of two GMO strains – Rainbow and SunUp – that were developed during this endeavor. (Gonsalves et. al). Resistant strains of other crops have since been released for commercial production using the same concept as this GMO papaya. Disease resistance; however, is only one of the many purposes that may be fulfilled using the concepts of genetic engineering.
The most commonly planted GMOs in the US are insect resistant “Bt” and herbicide tolerant “Roundup Ready” crops. These two varieties are favored to other strains so much so, that they dominate the acreage of many major cash crops. For the past three years, Roundup Ready soybeans have represented 94% of all soybean acreage. Roundup Ready corn and cotton have occupied 89% of all acreage during that same timespan. This year, 79% of corn and 84% of cotton planted contained the “Bt” gene (Recent Trends in GE Adoption). Simply put, these GMO strains have more market dominance than has ever been seen by a crop variety. Keep in mind; however, that these figures represent US acreage. Even still, the presence is staggeringly obvious. It begs one to ask, what do these crops do to make them so valuable?
Bt crops contain a gene from a soil bacterium called Bacillus thuringiensis. This organism is referred to as a biological pesticide because it produces an endotoxin that affects lepidopteran insects. Members of this group are often classified as worms, caterpillars, moths, and butterflies. This toxin has been extracted and used widely in conventional and organic agriculture for decades. Bt organisms utilize this very same gene to synthesize Bt toxins in every cell of the plant. In doing this, they are better protected from predation and require fewer pesticide applications.
Roundup Ready crops are called such because they must be used in conjunction with the popular herbicide Glyphosate, more commonly referred to as Roundup. This pesticide works by inhibiting the activity of another enzyme, EPSPS. When inactivated, plants are unable to synthesize three essential amino acids necessary for survival. This is where genetic engineering comes in. Roundup Ready crops contain a slightly modified version of the EPSPS gene. It is resistant to glyphosate inhibition, and therefore provides discreet resistance to applications of Roundup. The gene was discovered in a soil-born organism called agrobacterium. This particular strain was found populating a waste column at a glyphosate production facility. Go figure.
These two crop varieties essentially make pesticide applications more effective, thus reducing predation and competition. This, in turn, increases yields and overall profit. According to Purdue University, “Eliminating all GMOs in the United States,… shows corn yield declines of 11.2 percent on average. Soybeans lose 5.2 percent of their yields and cotton 18.6 percent. To make up for that loss, about 102,000 hectares of U.S. forest and pasture would have to be converted to cropland and 1.1 million hectares globally for the average case.” (Wallheimer). There is an obvious strength in using GMOs; however, there is also a lot of public scrutiny regarding their legitimacy. For one, the science is considered novel. Research in commercial production has only been collected for two decades, a span that is relatively small in agricultural time. There are many who criticize the US for adopting these biotech crops so hastily. On top of that, few people fully understand the science that goes into producing a genetically engineered organism. Opponents of GMOs capitalize on this uncertainty, coining terms such as frankenfood and criticizing scientists for playing with the natural world.
Regardless of which side you affiliate with, I believe it is of the utmost importance to educate yourself. Consider the implications of utilizing this technology, as well as the challenges we will face if we choose to go without. Recognize that genetic engineering gives humankind solutions that were never before possible, but that unforeseen consequences may also exist. From rice that contains a gene for beta-carotene synthesis to strawberries that contain a flounder gene for cold tolerance, there has never been a time where such unique lifeforms may be a reality. If you think that this is both frightening and incredible, you are definitely not alone.
About: I graduated from the University of Minnesota earning a BS in Applied Plant Science with an emphasis in plant improvement. During my undergrad, I spent 3 years working in a transgenic, small-grains breeding program. The foundation of this experience began with training in effective horticultural principles and plant breeding schemes. From here, I moved up into the laboratory where I worked extensively with tissue sampling, histotechniques, DNA extraction, amplification, isolation and sequencing. Naturally, this work was done in conjunction with the management of various agricultural systems; including transgenic growth chambers, greenhouse, and outdoor growing. I have since worked in pharmaceutical farming management and compliance in the developing cannabis industry.
Gonsalves, D., S. Tripathi, J. Carr, and J. Suzuki. “Papaya Ringspot Virus.” Papaya Ringspot Virus. USDA/ARS Pacific Basin Agricultural Research Center, 2010. Web. 23 Dec. 2016.
“How GM Papaya Saved Hawaii’s Papaya Industry.” GMOAnswers. SAIFood, Oct. 2015. Web. 23 Dec. 2016.
“Pocket K No. 16: Biotech Crop Highlights in 2015.” ISAAA.org. International Service for the Acquisition of Agri-Biotech Applications, June 2016. Web. 23 Dec. 2016.
“Recent Trends in GE Adoption.” USDA ERS. United States Department of Agriculture Economic Research Service, 3 Nov. 2016. Web. 23 Dec. 2016.
“Selective Breeding or Artificial Selection.” Selective Breeding or Artificial Selection. EVOL 3000, 24 Nov. 2013. Web. 23 Dec. 2016.
Wallheimer, Brian. “Study: Eliminating GMOs Would Take Toll on Environment, Economies.” Purdue Agriculture Communications. Purdue University, 29 Feb. 2016. Web. 23 Dec. 2016.