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Bananas Are in Danger: Can genetically modified fruit help?

Published on May 10, 2021 | Jacquelyn Turner | Future Tense | Slate.com

The banana as we know it is in trouble. Emerging reports suggest the fruit’s deadliest disease has been spotted in Peru and Venezuela, two of the world’s largest exporters of bananas. Following Colombia’s confirmed infections in 2019, it appears the disease is spreading through Latin America, and biosecurity measures meant to contain the pathogen have been unsuccessful. Much in the way the world was caught off guard by the COVID-19 pandemic, the banana industry is ill-prepared for what is poised to be a catastrophic wipeout of commercial bananas. Hope rests heavily on a newly developed genetically modified banana variety, which promises to save our banana from commercial extinction, but it may not be that simple.

Tropical Race 4, or TR4, the fungal strain that causes Fusarium wilt, has been spreading across the world for the past few decades. For experts who care passionately about bananas and people whose livelihoods depend on them, watching disease reports creep across the globe has been like watching a train filled with bananas hurtling toward unavoidable wreckage, frame by agonizing frame. Despite experts sounding the alarm for years, minimal international biosecurity efforts have meant that the disease has leapfrogged across the globe, beginning in Taiwan, then moving across Asia and into Africa. For decades, plant breeders have been trying to develop a banana that would please consumers and be immune to TR4. They tested wild bananas and attempted to crossbreed inedible wild species with edible domestic seedless varieties to try and transfer traits of immunity. By most accounts, these methods have been largely unsuccessful.

Now, the disease has touched down in Latin America, the primary exporter of bananas for markets in Europe and North America. Because the disease is often undetectable for up to two years, it is likely that TR4 exists in Latin America beyond Peru, Venezuela, and Colombia, waiting to be recognized and already steadily spreading.

Good news came at the end of February, when Australian researchers announced a new banana genetically modified to be resistant to TR4. The team managed to insert the gene that makes one of the wild banana varieties resistant into a commercial banana, and the researchers are now hoping to continue to boost the new banana’s immunity using CRISPR. But how did the industry come to think of GM as its last and only hope?

To answer that, we have to return to a different banana era. Nearly all of the bananas that are imported to the United States and Europe are “Cavendish” bananas, as has been the case for decades. But the Cavendish is not the thoroughbred of bananas; the fruit bruises easily, its per-plant yields are lower than other varieties, and it requires extensive agrochemical inputs to grow. Among cultures that entertain dozens of market banana varieties, such as India, Southeast Asia, and Central America, the Cavendish’s popularity is low; it just simply doesn’t taste as good as a banana can taste. However, the Cavendish has dominated in one important area: immunity.

In the 1950s, the horse the banana industry backed was a variety known as Gros Michel or “Big Mike.” This was a dreamy banana: It was resilient, the fruits were large, and it tasted sublime. But it was nearly wiped out in Latin American plantations by TR4’s predecessor, Tropical Race 1; like TR4, the disease rotted plants from the inside and spread through contaminated soil. Nothing could clear the pathogen from the soil once a farm was infected, and the spores remain there to this day. So the Gros Michel banana was quickly replaced in the fields with Cavendish, which was immune to TR1. Unfortunately for the banana industry, Tropical Race 1 turned out to be just the first deadly pathogen to threaten bananas as we know them. TR4 emerged in Taiwan in the 1990s, this time with Cavendish in its crosshairs. (TR2 and TR3 emerged in the meanwhile, but they’re less virulent and don’t target the banana family.) And because the Cavendish bananas are seedless (wild bananas are chock-full of seeds, but many consumers don’t like them) and thus cultivated by suckers, the nearly genetically identical plants are even more vulnerable to the spread of disease. For many scientists, the solution seemed clear: If no one could find a banana that was resistant to TR4 and fit both consumer expectations and an industry built on paper-thin production margins, they’d have to make one.

Enter CRISPR, the genetic editing technology. Early coverage of CRISPR technology focused on what it could mean for humans, with plenty of references to the 1997 film Gattaca. However, the food we eat is also a target. Being able to snip a gene that makes a crop susceptible to a pathogen is the stuff of fantasies—and in some cases very recently, reality—for GM giants like Monsanto and Syngenta.

While most corn and soy in American supermarkets are genetically modified, GM foods are currently banned in the European Union. (It remains to be seen whether the United Kingdom will retain these rules post-Brexit.) The GM Cavendish developed by the Australian researchers will have an easier path to markets in the United States, where it’s estimated that perhaps 75 percent of the food in our supermarkets has at least one genetically modified ingredient.

While research so far supports a lack of adverse health effects due to GMs, there are still plenty of valid critiques of the technology’s production and regulation. And for all that GM foods may help, they still fail to change many of the systems that create the crises they swoop in to solve. Producing genetically modified foods is currently expensive and therefore requires the backing of large corporations, whose priorities lie in yields and profit, not biodiversity or the health of workers and the environment. Like many crops grown in monoculture systems, bananas rely heavily on the frequent application of agrochemicals. This growing practice has had long-lasting and catastrophic effects on the lives of plantation workers and surrounding ecosystems, but producing bananas in crowded conditions has also made them vulnerable, allowing disease to quickly spread unhindered by the healthy soils or biodiversity that usually serves as nature’s insurance policy. The researchers pursuing transgenic bananas are currently seeking a new banana that will tuck neatly into Cavendish’s slot in this system, without disturbing, or questioning, any of these other elements.

The banana giant Fresh Del Monte Produce has teamed up with the Australian university that developed that first TR4-resistant GM banana to fund a five-year project to perfect and test the new variety outside of laboratory greenhouses. And although Del Monte has made no announcement yet, it wouldn’t be unexpected for this new banana to be patented (as the TR4-resistant genes already have been), meaning that unless other banana corporations like Chiquita and Dole develop their own varieties, they will be at a significant disadvantage while their Latin American plantations wilt beneath TR4. And for hundreds of thousands of smallholder banana farmers for whom bananas are a cornerstone of food security, a TR4-resistant fruit may remain forever out of reach.

Bananas are far from our only monocrop. Many of the world’s staples rest precariously upon just a handful of varieties. And while genetic modification promises us another tool to fight pathogens, it’s worth reflecting on just how reactive this process is. As with the pandemic that has swept across the globe this past year, preventing the initial spread of the disease would have been far less expensive than trying to mitigate after it has established itself in several countries.

How soon after planting Cavendish 2.0 will researchers need to start developing another genetically modified banana for Tropical Race 5? What about Tropical Race 6? And this is to say nothing of the challenges that bananas face under climate change. Yields may drop globally by up to 50 percent by 2050, and it remains unclear how resilient a GM banana might be in that scenario.

There are ways of growing bananas, and other crops, that support biodiversity and soil health. One example is the agroforestry systems used by many Indigenous groups across Latin America. These systems allow space between plants and grow multiple banana varieties so that disease is far less likely to spread. But the temptation of a shiny technological fix—and short-term profits—frequently mutes the conversations about how such measures could be integrated into larger-scale banana production, or how the products of environmentally conscious growers could be brought to willing consumers abroad.

Often, genetically modified foods are held up as a necessity to feed an ever-growing world, but what is less discussed is how the ways we grow that food actually exacerbate our problems. Industrial agriculture strips away topsoil, mandating the use of inputs like chemical fertilizers to replace lost nutrients. Growing genetically identical plants close together allows pathogens to spread quickly, decimating entire crops.

If bananas are a case study in the future of our food, we should think carefully about the framing of the case for GM crops. If the priority is short-term yields and band-aids against rogue pathogens, then GM is a step in that direction. But if long-term resilience and environmental health are in our sights, it’s worth reconsidering what efforts will get us there. A real solution will require a combination of strategies. For our banana, it is crucial to examine the biosecurity and monoculture methods that allow these diseases to spread so ferociously. Without significant changes, we’re just waiting for the next variant to take us by surprise.

 

Source: https://slate.com/technology/2021/05/banana-disease-cavendish-tr4-genetically-modified-crops.html

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