High School High School Biology and Chemistry

CRISPR-Cas9: A Chocolate Hero?

Is your chocolate at risk? Can CRISPR preserve America's favorite treat?

Image From: tejaschocolate.com

First, it is important to have some background knowledge on the cacao tree’s history and growing conditions. The cacao tree first originated in the Amazon river basin, and since then has spread to other tropical regions in Africa and Asia. It is normally grown close to the equator, where it receives the right amount of humidity and hot temperature. They are also typically grown with crops such as rubber that provide shade from the sun, and in soil that is rich with hummus (3). If these climate conditions are not meet, the yield of cacao decreases.

What this means is that climate change has taken and will continue to take a major toll on cacao farms. As found by the Intergovernmental Panel on Climate Change, “Under a “business as usual” scenario, those countries [the major cocoa bean producing nations] will experience a 3.8°F (2.1°C) increase in temperature by 2050 and a marked reduction in suitable cultivation area.” (2) So, there will not be enough suitable places to grow crops to satisfy demand solely due to an increase in temperature. Furthermore, the process of evapotranspiration will also reduce the result of the harvest. Evapotranspiration occurs when higher temperatures cause more water to evaporate from the soil and not enough rainfall occurs to offset the moisture loss. A 2011 study by Läderach, a climate change scientist, found that when you factor in the effects of evapotranspiration, “of the 294 locations examined in the study, only 10.5% showed increasing suitability for cacao production; the remaining 89.5% were likely to become less suitable by 2050.” (2) This re-emphasizes the need to find a sustainable solution to protect the future of chocolate.

However, these plants face more than just environmental problems. They are also constantly confronted with diseases that destroy entire harvests. A recent study at University of Arizona found, “About 70 percent of the world’s production of cocoa — chocolate’s main ingredient — comes from just six small countries of West Africa, where a blight disease that kills cacao trees is spreading rapidly, causing decline and death in some trees in less than one year after infection occurs.” (4) This shows that the majority of the worlds cocoa bean production is at a major risk of being severely depleted due to disease. The most common ailment is frost pod root in which a fungus stifles plant growth, and Witch’s Broom, another fungal infection also affecting the plant pod. To combat these ailments, the plants are often grown on small, family operated farms because the crops are very susceptible to disease making it disadvantageous to have huge plantations dedicated towards cocoa bean production. In fact, 90% of cacao trees are grown on farms that are less than 10 acres in size (4). Despite these attempts, researchers at Penn State found, “Each year, several plant diseases severely limit global production, with 20-30 percent of cocoa pods destroyed preharvest.” (5) From this statistic, it is evident a more radical solution to combat both climate change and disease is necessary.

CRISPR-Cas9 may be the chocolate hero everyone has been looking for. CRISPR stands for clustered regularly interspaced short palindromic repeats. It works by using an enzyme called Cas9 to target sections of the genome to modify the genetic code of the organism. Thus, certain traits can be deleted or added (5). Therefore, CRISPR could be used be used to create disease and drought resistant cacao trees. Research done by Andrew Fister, a postdoctoral scholar in plant science at the College of Agricultural Sciences at Penn State, found that a gene called TcNPR3 was suppressing the plant’s immune response. By using CRISPR, the team was able to breed more resistant plants that lacked the TcNPR3 gene (5). This process can be replicated for different diseases and to increase drought resistance. It would also ensure chocolate for everyone and protect small-holders and companies.

CRISPR-Cas9 does have its limitations though. Many of the genes that control the diseases which plague the cocoa fields are unknown, making the use of CRISPR impossible. However, Judy Brown, a plant virologist at the University of Arizona’s College of Agriculture and Life Sciences, is developing new ways to identify these genes. She states, “We take leaf tissue samples from infected cacao trees and fish for genetic material. This type of next-generation DNA sequencing is fairly new technology, and it allows us to look for unknown or undiscovered viruses in our samples.” (4) Thus, the unknown disease-causing agents may not prevent CRISPR from being effective.

However, there is also an ethical opposition to genetically modified organisms which may hinder their application. It is also important to consider other solutions such as diagnostic guides, clearing new spaces for cultivation, and planting new crops. Although the former two are expensive and unsustainable, they will probably always play a role in maintaining cocoa fields because of their already well-established role in the process. They can be used in conjunction with the first solution and CRISPR to identify disease early. (3, 4)

Overall, it is evident that the current solutions need to be implemented in order to prevent the destruction of an industry, the suffering of farmers, and a worldwide shortage of chocolate. If the changes are made carefully, maybe one day everyone will live in a world where cacao trees are resilient to climate and disease, and chocolate is abundant. Until then, the world must keep researching to ensure the changes being made are ethical and sustainable. Together, we can help save the cacao trees.

References and Footnotes:

  1. https://www.statista.com/statistics/819288/worldwide-chocolate-consumption-by-country/
  2. https://www.climate.gov/news-features/climate-and/climate-chocolate
  3. https://www.britannica.com/plant/cacao
  4. https://uanews.arizona.edu/story/cocoa-currency-and-chocolate-crisis
  5. https://www.sciencedaily.com/releases/2018/05/180510101245.htm


My name is Ellie Hummel and I'm a junior at DuPont Manual High School in Louisville, Ky. I am a contributor and the outreach coordinator for The Student Scientist. I love biology research and computer programming and hope to spread these passions to others through my writing. Over the course of the past three years, I have researched spinal cord injuries and axon growth. I also work for STEMY, a local non-profit dedicated to providing STEM resources to youth and lead my school's SNHS and HOSA chapters. In my free time, I play with my dog, Harry, and coach swim lessons.

1 comment on “CRISPR-Cas9: A Chocolate Hero?

  1. Amazing article! You should consider checking out my blog post about CRISPR-Cas9: https://therealsciblog.wordpress.com/2018/07/19/crispr-cas9/

    Liked by 1 person

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