Using CRISPR to Save Bananas
The past few weeks, the media has been making its rounds on the global banana crisis. A banana fungal disease called Fusarium Tropical Race 4 (TR4) is plaguing the world’s banana supply. In “Chapter 7 — CRISPR: The Frontier of Gene Editing” of Hungry For Disruption, Shen Ming Lee discusses how CRISPR, the new gene-editing kid on the block, could help prevent the Great Banana Crisis 2.0. This excerpt also discusses how Tropic Biosciences, a UK-based biotechnology company developing TR4-resistant Cavendish bananas using CRISPR, is shaking up the world of bananas — the world’s most popular fruit.
I really love bananas. I don’t think my life would be complete without them. I religiously freeze them for smoothies, dip them in nut butter as a snack, and use overripe ones to make the most delicious chocolate chip banana bread. It’s really the perfect fruit (although plant scientists will tell you it’s a herb). With its sweet and soft flesh encased in a peel, bananas are easily transportable, incredibly versatile, and extremely nutritious. With more than 150 countries cultivating over 105 million tonnes of bananas annually, it is easily the most important and popular “fruit” in the world.¹
When I go back to my home in Malaysia, a bunch of bananas are almost always perched on our fruit bowl. More often than not, the bananas are of the Pisang Awak variety, which is grown at a small farm near my home. Used in banana fritters, the stubby Pisang Awak is the most common variety grown in Malaysia. Back in the U.S., the Cavendish variety dominates. While there are over 1000 varieties of bananas, no other banana is grown or consumed as much as the Cavendish, which accounts for 47% of global banana production.² Named after William Cavendish, a British Duke who grew it in his greenhouses at Chatsworth House in the UK, the Cavendish makes up almost the entire banana export market — 99% to be exact.³
However, the Cavendish wasn’t always the most popular banana variety. Before the Cavendish was popularized in the 1950s, the dominant banana variety in Europe and America was the Gros Michel, a thick-skinned, creamier, and sweeter banana.⁴ There’s a reason it isn’t around anymore. By 1965, a strain of fungi called Tropical Race 1 (TR1) had wiped out production of the Gros Michel, forcing major producers to switch to the Cavendish (which is resistant to TR1). Today, just as the Gros Michel was devastated by TR1, the Cavendish is being threatened by a new disease — the Tropical Race 4 (TR4). And out of the 1,000 varieties of bananas, TR4 only affects the Cavendish. Yikes.
Just like TR1, TR4 is deadly. The fungus, which can live undetected in soil for decades, invades banana plants through the roots and then chokes them to death by slowly starving them of water and nutrients. The end result is soil infected by TR4 and a field entirely useless for growing anything.⁵
“When TR4 hits, the destruction is near-total. It looks like somebody’s gone to the plantation with a herbicide,” explains Randy Ploetz, a professor at the University of Florida’s Tropical Research and Education Centre who has spent nearly three decades of his life researching the impacts of TR4.⁶
According to Ploetz, he first learned about TR4 when he received a mysterious package containing infected soil from Taiwan in 1989. Since then, TR4 has spread to Indonesia, Malaysia, Mozambique, Lebanon, Israel, India, Pakistan, Australia, and many more countries. “It’s everywhere,” urges Ploetz.⁷ With fears of TR4 spreading to Latin America, the world’s dominant banana producer, Ploetz warns that the Cavendish is at risk of an extinction more catastrophic than the Gros Michel, because unlike the Gros Michel TR1 epidemic, there is no TR4-resistant banana variety to replace the Cavendish. The world is facing a major Cavendish Catastrophe.
What is our best chance of saving one of the most important crops in the world without using controversial gene modification techniques? Tropic Biosciences has a solution brewing in its labs. The UK-based biotechnology company is developing TR4-resistant Cavendish bananas using CRISPR, a DNA editing technology shaking the world of genetic crop improvement. The DNA editing molecule called CRISPR-Cas9 is used to molecularly snip off and deactivate specific genes in banana cells. Ultimately, these small tweaks result in banana plants that are resistant to TR4. The company has also used CRISPR to create bananas that ripen more slowly than a normal Cavendish, potentially stopping millions of dollars’ worth of bananas from spoiling every year. Evidently, these small genetic tweaks have big implications for a US$12.4 billion banana export market.⁸
The revolutionary thing about using CRISPR is that unlike GMOs, the plant cells that Tropic Biosciences is cultivating is almost genetically identical to any Cavendish banana on the market.⁹ Essentially, there is no trace of foreign genes in its banana cells; the slight differences lie in a few genes being switched off. Therefore, CRISPR is arguably not a GM technique. Unlike a highly controversial GM Cavendish banana, a CRISPR-edited, TR4-resistant variety will likely be accepted by consumers worldwide. Ultimately, CRISPR alone could save the Cavendish from extinction.
When WIRED writer Matt Reynolds visited Tropic Biosciences’ research labs just outside of Norwich, UK, he witnessed the company’s CTO, Ofir Meir, “holding the future of the banana in his hand.” With rows of grey cell clusters in a Petri dish in hand, Meir confidently exclaimed: “One day, these shoots will become a field in South America.”¹⁰
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Hungry for Disruption offers a futuristic vision for embracing the scientific and technological advances in food for the coming decades. The book explores how breakthrough innovations in smart agriculture, novel farming systems, genomics, cellular agriculture, and food waste management will play a key role in the future of food and agriculture. This publication is a series of posts that brings the stories of farmers, entrepreneurs, investors, scientists, and innovators from the book alive.
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Notes:
¹ Roger Rossignol, “Bananas World’s Most Popular Fruit. — A Passion For Food,” Westcountry, May 25, 2017, http://www.apassionforfood.co.uk/bananas/.
² “Banana Facts And Figures,” FAO, accessed February 23, 2019, http://www.fao.org/economic/est/est-commodities/bananas/bananafacts/en/#.XHFzhehKguH.
³ Matt Reynolds, “The Banana Is Dying. The Race Is On To Reinvent It Before It’s Too Late,” Wired, OCtober 11, 2018, https://www.wired.co.uk/article/cavendish-banana-extinction-gene-editing.
⁴ Reynolds, “The Banana Is Dying.”
⁵ Reynolds, “The Banana Is Dying.”
⁶ Reynolds, “The Banana Is Dying.”
⁷ Reynolds, “The Banana Is Dying.”
⁸ Daniel Workman, “Bananas Exports By Country,” World’s Top Exports, January 15, 2019, http://www.worldstopexports.com/bananas-exports-country/.
⁹ Cerier, “Genetic Engineering, CRISPR And Food: What The ‘Revolution’ Will Bring In The Near Future.”
¹⁰ Reynolds, “The Banana Is Dying.”
