Genetically modified (GM) crops are plants engineered to provide better yield, resistance to pests and disease, reduced spoilage, and a plethora of other generic or highly specific advancements, such as their use in the generation of medicines and biofuels.
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GM crops have the potential to alleviate world hunger and climate change, optimizing the use of land to lessen the environmental impact of farming, calling for the use of significantly lower quantities of chemical agents, and boosting the nutritional content of food.
Humans have been directing the evolution of crop plants since the dawn of agriculture, with one of the first done by biochemical means in the 1980s with herbicide-resistant tobacco, wherein a gene was inserted via plasmid into a tobacco plant cell culture, and a single resistant cell bearing the chimeric gene was then selected and used to grow a new plant. This allowed farmers to spray a field with herbicide without the worry of harming their crop, and within a decade crops producing their own pesticide that is safe for human consumption were developed.
What is the global benefit of GM crops?
Since this time GM crops have spread to represent over 10% of global cropland, particularly soybean, maize, canola, and cotton crops of which 44% are GMOs. The most widely adopted commercial modifications to these crops are tolerance to specific herbicides and pests, allowing the adoption of broad-spectrum low-cost herbicides and eliminating the use of insecticides.
As these chemicals require energy to apply to a crop field in the form of farm machinery, one aspect of environmental benefit can be measured directly by lowered greenhouse emissions from these sources, estimated to be around 2.7 kg of carbon dioxide per gallon of tractor diesel consumed.
Additionally, fields do not need to be tilled as intensively to remove weed plants, saving over 20 liters of fuel per hectare. The adoption of no-till systems enabled by GM crops also keeps greater quantities of carbon sequestered in the soil, also possibly reducing the number of other greenhouse gasses such as methane and nitrous oxide released.
GM crops are also produced that are engineered to better grow in or withstand changes in environmental conditions, particularly crucial given the global climate crises. Rice is one of the most crucial crops in the world, and the areas in which it is primarily grown are at an increased risk of high-frequency flooding.
Where normal rice usually dies within around five days following complete submersion by flash flood, Scuba rice is able to become dormant when completely submerged in water and can survive in this state for several months.
This strain of rice was created following the discovery of the ethylene response factor (ERF) gene submergence 1A in the late-1990s, which was incorporated into several strains of rice by 2010 by repeated backcrossing, allowing any locally favored type of rice to be made more resistant to flooding. The submergence 1 locus contains several ERF genes in rice, most containing Sub1B and Sub1C.
Aus- and indica rice tolerant to flooding bear the Sub1A gene, of which the Sub1A-1 allele has been demonstrated to be the major determining factor in flood tolerance. In non-tolerant plants the usual response to flooding is to undergo leaf elongation to escape to open-air, ultimately encountering energy limitations, and upon desubmergence many plants also undergo severe oxidative stress due to sudden air and light exposure with a reduced number of chloroplasts.
Sub1A-1 bearing plants instead enter a quiescent state that reserves carbohydrate stores and limits the build-up of metabolic by-products, in addition to inducing the production of reactive oxygen species scavenging enzymes that limit ROS-induced damage.
What is the economic benefit of GM crops?
A study by Yorobe & Smale (2012) examined the economic benefit of the introduction of Bacillus thuringiensis maize in the Philippines, engineered to produce chemicals toxic to insects. Besides directly improved farm income sourced from improved yields, with less crop being lost to pests, more free time was allowed to the farmers and workers, letting them earn more money from off-farm sources and improving overall household income.
Similarly, Bennett et al. (2006) identified an economic benefit to South Africans when adopting Bt cotton in the late 1990s, where crop yields from Bt cotton farms were 89-129% larger than those growing conventional cotton.
Weeding is one of the most time-consuming and size-limiting factors in African farms, and Gouse (2013) calculated that 10-12 days per growing season per person working on the farm were saved by the change to herbicide-resistant maize and adoption of broad-spectrum herbicides.
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What is the personal benefit of GM crops?
While the benefits of increased yields and farm profits are amplified in developed counties with access to mechanized equipment it is the smaller-scale farms, particularly in developing nations, that gain most human health benefits, avoiding exposure to harmful chemical agents that would otherwise have to be applied by hand-held instruments.
Many pesticides must be applied multiple times throughout a season, amplifying the chances of becoming seriously ill with time. Following the introduction of Bt cotton to South Africa reports of pesticide poisoning dropped from over 50 per year to less than 10 within four years, and similarly, Hossain et al. (2004) reported that while one-third of non-Bt cotton farmers in China reported pesticide poisoning in a given time-frame, only 9% of Bt cotton farmers did.
In India Bt cotton is estimated to have prevented between 38 to 144 million instances of pesticide poisoning between 2003 and 2013, and further, in a 2011 paper by Gruère and Sengupta, Bt cotton is thought to have prevented over 75,000 suicides in India over three years by improvement of business and lessened the occurrence of poor health.
Nutritionally enhanced GM crops have also saved millions of lives around the world, and have the potential to save many more. GM crop-based tactics have several advantages over traditional food supplementation efforts in developing nations in particular, where communities can easily become isolated when supply lines are cut.
As these communities often rely on a highly homogenous diet consisting of a single staple crop, a suitable GM crop, once established, could potentially sustain them indefinitely.
Golden Rice is one of the greatest examples of biofortified rice, taking genes from the bacterium Erwinia uredovora and the daffodil to alter the carotenoid biosynthetic pathway of the rice and produce β-carotene, around 35 µg/g of dry rice in modern varieties. β-carotene metabolizes the production of vitamin A in humans, and Golden Rice has so far saved the vision and life of millions around the world.
Rice, maize, wheat, and other staple crops have similarly been biofortified with numerous vitamins and minerals or their metabolic precursors, improving their nutritional profile in a more cost-effective way than equivalent supplementation could achieve.
- Brookes, G. & Barfoot, P. (2013) Key environmental impacts of global genetically modified (GM) crop use 1996–2011. Biotechnology in Agriculture and the Food Chain. doi.org/10.4161/gmcr.24459
- Yorobe, J. M. & Smale, M. (2012) Impacts of Bt maize on smallholder income in the Philippines. AgBioForum.
- Bennet, R. et al. (2005) The economic impact of genetically modified cotton on South African smallholders: Yield, profit, and health effects. The Journal of Development Studies. doi.org/10.1080/00220380600682215
- Smyth, S. J. et al. (2015) Global economic, environmental and health benefits from GM crop adoption. Global Food Security. doi.org/10.1016/j.gfs.2015.10.002
- Hossain, F. et al. (2013) Genetically Modified Cotton and Farmers' Health in China. International Journal of Occupational and Environmental Health. doi.org/10.1179/oeh.2004.10.3.296
- Smyth, S. J. (2020) The human health benefits from GM crops. Plant Biotechnology Journal. doi.org/10.1111/pbi.13261
- Septiningsih, E. M. et al. (2013) Applying genomics tools for breeding submergence tolerance in rice, in Translational Genomics for Crop Breeding: Improvement for Abiotic Stress.