Support Provided ByLearn More

Can the Banana Be Saved?

ByVirginia GewinNOVA NextNOVA Next
Logging trucks are a frequent sight in central mainland Malaysia.

In central mainland Malaysia, as the cleared oil palm plantations are readied for a new crop, decaying fronds litter rolling hills of rust-colored soils. Amid the detritus, a verdant wild banana clump sits in a nearby roadside ditch. The six-foot long leaves shiver as Anuar Rasyidi emerges drenched in sweat, his machete in one hand and a decaying stalk of tiny fruit in the other. Passersby would never guess that the seeds within these bananas are on a global most-wanted list.

Rasyidi is one of a six-member team from the Malaysian Agricultural Research and Development Institute (MARDI), who have spent the last year tracking down these populations, waiting sometimes months for fruits to ripen. On return trips, it’s not unusual to find that individual plants have disappeared. In fact, the MARDI team doubts that many of these wild trees will still be standing even three years from now given the rate at which forests are being cleared for timber and replaced with palm oil plantations, which covered just under 1.5 million hectares in 1985 but sprawled over 4.7 million hectares in 2015. Loaded logging trucks are a constant presence; 22 passed by one July morning.

At first glance, it’s unclear why these bananas are worth the effort. The scraggly bunches aren’t edible, and the fruits are full of seeds. But these seeds, missing from international gene banks, hold the genetic diversity that could one day help prevent the feared “Bananapocalypse,” where a single pathogen could wipe out a majority of the world’s banana plantations.

The world’s most popular fruit, the Cavendish banana, is also one of the least genetically diverse. These seedless bananas destined for the $11 billion export market are, essentially, clones. That leaves the humble Cavendish vulnerable to diseases that can take advantage of its limited genetic diversity.

And now, just such a soil pathogen is marching out of Southeast Asia, threatening to devastate plantations around the world.

Anuar Rasyidi emerges with the fruit of a wild banana tree.

The plants that Rasyidi collected won’t end up on supermarket shelves, nor will any of Malaysia’s other wild bananas, but some of their genes might. Banana is just one of dozens of crops—from wheat to rice—that will likely need an infusion of genes from their cousins able to withstand disease and drought as the climate changes. Today’s elite crop varieties—agriculture’s high performance vehicles—may need to add some evolutionarily-irreplaceable parts from the unique jalopies on the side of the road. Despite their potential, the wild relatives of crops are disappearing all over the world. At least 70% of crop cousins are deemed in urgent need of collection . A 2013 study placed the value of so-called “crop wild relatives” at a staggering $196 billion .

“Any one of those populations could have novel characteristics. That’s the difference between crops and their wild relatives.”

Malaysia is only one of 23 countries conducting seed collecting missions as part of the 10-year, $50 million global Crop Wild Relative initiative to amass over 4,700 seed collections from 350 cousins of 29 high-priority crops. The effort is funded by the Norwegian government and overseen by the Crop Trust, a Bonn, Germany-based organization that works to conserve agricultural biodiversity in international seed banks. The Royal Botanic Gardens, Kew, manages the country agreements and seed banking process, including training country-based crews how to collect the seeds. One set of the seeds stays in the country. The remaining seeds are sent to Kew’s Millennium Seed Bank outside London, where they are either made available to interested plant breeders or serve as a back-up.

Support Provided ByLearn More

It can be difficult—and expensive—to find wild bananas ripe enough to have produced mature seeds, yet not already eaten by forest critters. In four days, the MARDI team traveled from the sultry lowlands outside Kuala Lumpur to the cooler Cameron Highlands—a trip that yielded 10 collections, from five of the 12 target species and subspecies. “Any one of those populations could have novel characteristics. That’s the difference between crops and their wild relatives,” says Alexandra Davey, a Royal Botanic Gardens, Kew, program officer who joined the MARDI collection trip and is responsible for crop wild relative collecting partnerships in Asia. MARDI’s goal of 60 collections of the 12 targets will likely take about 25 trips.

Depositing seeds in international genebanks is not a trivial matter, either. Once shared, traded, taken with abandon around the world, plants, especially their easily-swapped seeds, are genetic resources now considered the property of governments. Some biodiverse, often developing, countries are understandably wary of western companies profiting from their sovereign seeds or traditional knowledge, and they’re choosing not to share.

The race to collect and characterize wild diversity before it disappears is only the beginning. Making use of the seeds is yet another herculean task. Even if countries are willing to share their seed for use in commercial breeding efforts, the banana industry has largely gutted their R&D operations. There are currently only a handful of perennially underfunded, public banana breeders to carry out what is, in reality, a 10–20 year project to breed one new variety.

Bananas are nearly as ubiquitous as wheat or rice—they’re eaten in 167 countries. It is the world’s fourth most produced crop and a vital food staple in Africa. It also also serves as a cautionary tale: If global diversity isn’t cataloged, shared, and eventually incorporated into the crops we all depend on, the chance of disruption or even catastrophe remains uncomfortably high. On average, almost 70% of food supplies and production systems in every country depends on genetic diversity that originated far away. “Countries are hopelessly, chaotically interdependent on each other,” says Colin Khoury, a crop diversity researcher with the International Center for Tropical Agriculture.

‘The Masterpiece of Malaysia’

Banana samples take on an other-worldly look outside the jungle. Back at the MARDI lab outside Kuala Lumpur, they are splayed across lab benches while they are catalogued, photographed, and processed. They look like relics from a distant time. Vertebrae-like stalks erupt in massive flowers of yellow, peach, or purple. The assorted bunches are a hodgepodge: sparse, abundant, straight, curved, skinny, stubby. They are, in a sense, fossils—nature’s evolutionary experiments that survived fierce competition, climatic shifts, and likely relatives of the same diseases that now plague commercial crops.

Bananas originated in Southeast Asia, notably in Indonesia and Papua New Guinea. They are a wealth of diversity that is a point of pride across the region. Much like apples in the U.S. Pacific Northwest, there are at least a dozen banana varieties in Malaysia’s markets. Dozens more distinct, locally-adapted varieties are maintained by individual villages. Maimun Tahir, the head of the MARDI Crop Wild Relative collection project, beams when she shares the country’s popular Berangan banana, which has a dry, sweet, slightly acidic taste. Radyidi calls it “the masterpiece of Malaysia”.

While bananas are the world’s most popular fruit, most people—especially those in countries that can’t grow bananas—eat the Cavendish, largely for two reasons: it produces the most fruit and can be shipped green around the world, left to ripen on supermarket shelves.

It’s unclear how an English gardener came to possess a Cavendish plant from Mauritius 180 years ago, but missionaries subsequently spread it to Samoa and beyond. The high-yielding variety eventually took the place of the better-tasting Gros Michel banana, the world’s first widely-grown export banana, which was wiped out by the first version of the fungal Panama disease in the 1950s.

In recent years, a new strain of Panama disease, dubbed tropical race 4, or TR4, has devastated Southeast Asian banana plantations and leapt across the oceans to Australia, Africa, and the Middle East. Its spread to other continents is not easily explained by infected irrigation water or machinery, says Randy Ploetz, a plant pathologist at the University of Florida in Homestead. It moves so easily that, earlier this year, a convention of banana producers and researchers switched their meeting location from San Jose, Costa Rica, to Miami, for fear that TR4 would hitchhike on the shoes of attendees coming from Asia, Ploetz says.

Given the expense and difficulty of breeding new bananas, diseases are largely kept at bay with pesticides. “The truth is, for the moment, it is cheaper for banana producers to flyover and spray,” says Sebastien Carpentier, a crop breeder at the banana gene bank in Leuven, Belgium.

The Cavendish, like all commercial bananas, is seedless, which means it reproduces asexually. It also means that the “offspring” are merely clones of the parent. Same genes, same vulnerabilities. When clones are planted around the world to the exclusion of other genotypes, their vulnerabilities can become worldwide liabilities. (Breeders could overcome some of these vulnerabilities by selecting clone mutants that are less susceptible to disease and could slow the spread of an epidemic, but that would be a short term fix at best.)

True disease resistance will only be achieved by introducing genetic diversity into the crop, such as breeding with wild relatives, says Gert Kema, a tropical phytopathologist at Wageningen University in the Netherlands. But breeding programs are costly and time consuming, and adequate funding for such efforts won’t happen until TR4 hits the Americas, Kema predicts. “Industry can be very short-sighted,” he says.

“Cavendish is the Red Delicious of bananas—it stores forever but has a horrible taste.”

In recent years banana exporters have largely gotten out of research, Ploetz says, becoming little more than middlemen. That has left academia and non-profit organizations to build the next banana with comparatively little funding and sparse access to seeds and genetic material. Even interested crop breeders like Alan Chambers, a newly hired tropical fruit breeder and geneticist at the University of Florida in Homestead, is circumspect about his ability to make much progress. “Without funding and access to new genetic material, we have to move on to a different crop,” he says.

Some banana breeders are holding out hope that TR4 may cause plantation owners to rethink the global Cavendish monoculture. “Race 4 is a threat, but it’s also an opportunity to start growing more diversity,” says Rony Swennen, the lead banana and plantain breeder for the International Institute of Tropical Agriculture (IITA) in Arusha, Tanzania. He also hosts the world’s largest international banana collection at his home university at the University of Leuven in Belgium. Of the 1,500 gene bank deposits in the collection, only 15% of the varieties are wild bananas, and those come from a single seed, hardly encompassing the diversity present in even a single population. “We need much more wild bananas, from everywhere in Asia—especially from places like Indonesia and Papua New Guinea, where good tasting bananas first originated,” Swennen says.

Receive emails about upcoming NOVA programs and related content, as well as featured reporting about current events through a science lens.

There are certainly opportunities to grow better tasting bananas. “Cavendish is the Red Delicious of bananas—it stores forever but has a horrible taste,” says Allan Brown, a fruit breeder also at IITA.

TR4 isn’t the only troubling disease. Today’s banana will need to have resistance to other diseases, too, such as against the black sigatoka fungus, the bunchy top virus, and bacterial wilt. There are currently no sources of resistance against the latter two, but it may be lurking in wild bananas yet to be collected. “We want to breed for long-term resistance, to win the never-ending battle against diseases for at least a longer time,” Swennen says.

The Crop Trust is funding Carpentier to do preparatory work in advance of breeding on wild banana seeds already in gene bank collections. Wild cousins are distant enough from today’s crop varieties that it takes years of work growing the seeds and identifying their valuable traits before the material is ready to breed with commercial varieties.

International relations concerning the exchange of plants and seeds, however, have changed drastically in recent decades. The 19 th -century English gardener who spread the Cavendish may have received plants from what was then a British territory without complication, but taking bananas from the now sovereign nation of Mauritius—without their knowledge or consent—would be considered biopiracy.

A Sensitive Issue

While plants, especially crops, have been moved around for centuries—the Cavendish is just one of many—countries have grown increasingly concerned about industry efforts to profit from their native resources.

The concerns over biopiracy that currently stymie seed sharing began over two decades ago for reasons unrelated to bananas. They largely arose as Western researchers started patenting indigenous plant properties and genes to develop pharmaceuticals. In one of many instances, the issue surfaced when Indonesia controversially rebuffed the World Health Organization’s request for access to their influenza strains in 2007 . They claimed that companies in developed countries had previously profited from their strains, without Indonesia’s consent, while making a commercial vaccine—a vaccine that people in developing countries couldn’t afford. The dispute helped cement the need for equitable collaborations, that a country’s genetic resources are sovereign, and that access should return benefits to the host country.

The Indonesian case highlights how trust has remained a concern even after the International Plant Treaty on Plant Genetic Resources for Food and Agriculture entered into force in 2004. The treaty created a standard material transfer agreement that articulated the rights and obligations of provider and recipient to facilitate access to seeds of 64 of the world’s most important crops. In exchange for access, companies or countries profiting from the genetic resources are supposed to share the benefits of commercial success by providing money to support farmer rights and conservation activities. But it takes time for countries to harmonize their policies. And while a few governments have donated to the access and benefit sharing account, big seed companies have yet to make any payments.

When the Crop Trust approached several Southeast Asian countries to apply for funding to collect banana wild relatives, Vietnam, Nepal, and Malaysia opted in while Sri Lanka and Indonesia opted out—to Carpentier’s disappointment. In addition to taste, bananas in drier areas of Indonesia are likely to use water more efficiently, a trait that’s highly sought after, says Carpentier. If bananas could be bred to thrive on less water, they would not only save increasingly precious supplies, but also be grown in drier conditions where they would likely suffer from fewer fungal diseases.

Any number of things might prevent a developing country from sharing seeds—from high-level political concerns to a lack of capacity. “Seeds are a sensitive issue,” Carpentier says.

If anything, the Crop Wild Relative project demonstrates that collaborations to collect and utilize seeds appear to moving in a positive direction, says Hannes Dempewolf, project manager at the Crop Trust. “We now have 23 countries we provide with support to collect crop wild relatives—this serves as a clear showcase that the multilateral system is gaining trust,” he says. “Our project would have been much more difficult 15 years ago.”

Roughly one-third of the project’s target collections are already at the Millennium Seed Bank. “Conserving this wild genetic material now and making it available for research is a huge step towards tackling the global problems we face,” Davey says. Khoury agrees. Given the current international political landscape and the fact that most countries have yet to fully institutionalize their Plant Treaty commitments, the Crop Wild Relative project has been remarkably successful—safeguarding threatened diversity even though it may not be used for years to come, he says.

Carpentier hopes to negotiate an agreement to conduct pre-breeding work with MARDI, but fears the Malaysian organization may be short on staff. At the same time, Kema is raising funding to bolster a new, commercial banana breeding program that builds on his existing collaborations with researchers in Southeast Asia, including Indonesia, to use wild resources to produce a continuous stream of new dessert and cooking banana varieties.

Still, Kema says any effort will take at least a decade, a lot of money, and trust between partners to come up with an equitable, viable business plan. “We’re not doing this to make money, but to come up with true solutions,” he says.

And those solutions will almost certainly benefit from wild banana genes. While it may get harder to find some of the wild banana subspecies in Malaysia, they are known for their resiliency—the very trait that future bananas might need most. “People say it’s hard to kill a wild banana,” Tahir says.

Photo credits: Virginia Gewin, CypressHI/Flickr (CC BY-NC-ND)

Funding for NOVA Next is provided by the Eleanor and Howard Morgan Family Foundation.

National corporate funding for NOVA is provided by Draper. Major funding for NOVA is provided by the David H. Koch Fund for Science, the Corporation for Public Broadcasting, and PBS viewers. Additional funding is provided by the NOVA Science Trust.