Authors Luis Suarez, Moe Ameri, Bianca Leuzzi and Colin Michie of the American University of the Caribbean School of Medicine.
Dr. Colin Michie has worked as a paediatrician in the United Kingdom, Africa, the Caribbean and the Middle East. He is specialised in nutrition, haematology and infectious diseases. Now the Associate Academic Dean for the American University of the Caribbean Medical School in St. Maarten, his enthusiasm is training medical students and healthcare teams to ensure they deliver better value healthcare.
Bananas and plantains are planted deep in our cultures: They are probably the fourth largest fruit crop in the world. Whether taken as a quick snack or cooked into maduros, sese, splits or breads, they are a dietary staple. The world’s banana and plantain trees are in danger from a potentially devastating fungus, Fusarium wilt Tropical Race 4 (also known as Panama disease).
In August of this year, Panama disease was identified in La Guajira, Colombia – the country declared a state of emergency. Colombian farmers cultivate some 50,000 hectares of bananas, mostly for export, but eight times more, 400,000 hectares, of plantains for local markets. This pattern of agriculture is common in many countries from Uganda to the Dominican Republic.
Banana backgrounds
Banana trees were introduced from South East Asia to the Caribbean in the 16th century. Their Latin name is Musa sapientum. Plantains (Musa paradisiaca) are close relatives. It was not until the 1880s that their mass production – in particular the “Gros Michel” banana – became a global trade. At this time in the Caribbean, banana crops replaced sugar cane in those islands and mainland plantations with more rain.
This is not the first time the banana has been in danger from Fusarium. In the 1950s, Race 1 of the Fusarium wilt fungus devastated the Gros Michel cultivar. Thousands of hectares of bananas in Suriname, Honduras and Panama were lost. Local economies were damaged and there was financial hardship, displacement of farmers and political repercussions. In many areas, plantations were then replaced by the more disease-resistant and high-yield Cavendish, together with systems, to handle this different type of fruit.
The Cavendish banana stays green for several weeks after picking and is ideal for export from tropical to temperate climates. Now over 95% of exporters grow this one strain – the Cavendish. The risks of this monoculture, without crop rotation, are becoming evident now. Like many other systems that lack diversity, banana production is threatened. A parallel is seen in the susceptibility in the internet world to Mirai malware. Our computer systems are a little like monocultures and lack diversity. They are therefore often susceptible to outside invaders from these bots!
The threat and possible genetic solutions
Since the early 1990s, Fusarium wilt TR4 has been killing banana trees across Asia, Australia, and Africa. Fusarium is a fungus that lives in soils; it persists for many years, and infected plants cannot be treated. TR4 destroys the banana’s vascular system, causing leaves to wilt; no fruit are produced. No agricultural fungicides or containment methods have been effective to date. Quarantine has been the main strategy for disease control. Until this year, our region, Musa trees in Latin America had not been affected.
This is of special importance to the Americas as South America is home to several top banana exporters. Furthermore, 92% of Fair Trade bananas are produced in this region too. Setting aside the financial implications of such a pandemic, TR4 can potentially deprive millions of people who use plantains as a primary cheap food source. Fusarium species infect many other plants, including strawberries and broccoli. They can infect humans too – some of their species can cause eye infections; they can also infect those with compromised immune systems.
Could a resistant banana be bred by farmers? How can we avoid this banana and plantain extinction, so that our prized Musa fruits do not go the way of the Saber-tooth Tiger? Banana cultivars do not make seeds so ingenious attempts to find or develop resistant mutants have been under way for many years. The use of irradiation to produce new mutants has been particularly successful in Guandong, China, and the Philippines where resistant banana plants have been developed and are in trials. Another strategy relies on genetic engineering, using a tool that can allow researchers to target and remove or enhance specific genes. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is one of these.
Researchers from different groups around the world recently reported that they had enhanced resistance genes in a Cavendish, as well as turning on immune response genes within the banana genome. Other techniques have involved inserting a resistance gene from a different banana strain into the Cavendish. So far, there is no news about resistant plantains... Although these results look promising, there have been many debates about genetically modified organisms (GMOs) or genetically engineered food crops. GM foods have been criticized for being unsafe and going against what nature intended. The processes of creating these is carefully regulated in Europe and North America to ensure that modified genes do not have any impacts on local environments.
Would you eat a GM banana or plantain?
So here is the challenge. If a genetically engineered banana could be developed to replace the current Cavendish, or a super-plantain that would not be troubled by wilt fungus, would you eat it? What do you think of genetically modified foods? Do they concern you? Do you check food labels and exclude them from your shopping basket? As labels are not required for GM products in all countries, it is likely that many products on St. Martin’s supermarket shelves include GM products. The author’s brief survey over one weekend identified GM products for sale in several different supermarkets on the island.
At present, genetically engineered crops include soya, corn, cotton, canola (or rapeseed) squash, alfalfa, sugar beets, Hawaiian papaya and Aquabounty salmon. These have been engineered to grow more rapidly, or have protection against various plant pests. The result is fewer pesticides and weed-killers need to be used by those farming them. Engineering of this type has been practised since the 1980s. No human health problems have been identified with the systems currently in use. Potential benefits from some engineered crops include increased yields and improved tolerance to different climates. With the development of climatic changes related to rising greenhouse gases, this will become increasingly important to ensure food security for all of us.
Other solutions
Banana and plantain monoculture have problems other than those related to a risk from this fungal infection. There are other banana pests and problems. For instance, a banana monoculture often has a higher water requirement. By changing focus to improving soil health, moves such as intercropping with coffee, growing to organic standards, providing shade trees and natural barriers to pests (such as lemongrass), some improvement in the battle against fungus is possible.
Rotating crops every few years or with different lower yield but more resistant bananas also mitigate the risks from TR4 by reducing soil pathogens. Prior to the announcement from the Colombians, a specific campaign was started with producers in this region: there is a Fusarium Working Group. These changes have already begun to increase the cost of our bananas and plantains. Your top banana may change its name, your favourite plantain may become more expensive, but an important battle has begun. Your views on GM processes are important!
