People love their bananas, one of the most popular fruits consumed in the world. We generally only eat one banana cultivar, the Cavendish, which replaced another cultivar that was susceptible to Panama disease, a type of Fusarium wilt. Unfortunately, the Cavendish banana has been devastated by a new form of that fungal disease which might lead to the end of the availability of the banana in your local grocery store. But there is hope – scientists are developing GMO bananas that may save the fruit from becoming a distant memory.
Let’s take a look at how the banana industry got here and how GMO bananas may be the salvation for the delicious yellow fruit.
All about bananas
The Cavendish banana makes up about 50% of banana production across the world. However, because of its ability to survive transportation from the tropics to the USA, Canada and Europe, the Cavendish cultivar makes up nearly all of the bananas in international trade – trade that is valued at over US$12.4 billion annually. Other cultivars of bananas just don’t do well with shipping long distances, and the fruit becomes either visually unappealing or inedible during shipment. Markets that are close to the growing regions, like Australia and Mexico, have access to a wider range of this delicious fruit.
The Cavendish banana is grown all over the tropics. It is a form of the sweet banana species, Musa acuminata, which makes up almost all of the bananas we consume. The Cavendish banana was developed in a greenhouse in England, and named after William Cavendish, 6th Duke of Devonshire. It then was shipped from England to tropical locations across the world, including West Africa, Southeast Asia, and Central and South America.
One of the major problems with the cultivation of the Cavendish banana is that almost every plant is a clone of the original Cavendish plant. That means if a disease attacks one plant, it pretty much means the destruction of plantations across the world. Originally, the Cavendish cultivar was resistant to the Fusarium wilt, but a new, possibly long-dormant, strain of the disease was discovered in banana plants in Taiwan in 1989. This new strain of the Fusarium oxysporum was called tropical race 4 (TR4).
The Fusarium wilt, which is resistant to fungicides and other pesticides, is highly contagious, and easily moves from plantation to plantation. The only way to eradicate the disease is to burn the whole plantation, but the fungus might still be in the soil, returning soon after replanting of new Cavendish banana plants.
Given the fact that all Cavendish bananas are a clone, the fact that the fungal diseases easily passes from plant to plant and can be carried from continent to continent, and the fact the Fusarium wilt cannot be killed or treated, there is concern across the world that the Cavendish banana could go extinct. And since it is really the only type of banana that can transported long distances, we would never see another banana unless you travelled to the tropics, near plantations.
So banana researchers (yeah, it is a thing, and I volunteer) looked in two different directions – hybridizing a new cultivar that might be acceptable for long distance shipping with resistance to the disease, or developing a genetically modified Cavendish banana with Fusarium fungus resistance.
Some scientists who are trying to create a hybrid between TR4 subspecies and cultivars that they hope will confer resistance to the fungus while retaining the key characteristics of the Cavendish. However, this is a difficult feat because the hybrid generally contains a blend of characteristics, including ones that reduce the attributes of the Cavendish that make it so popular with consumers and producers.
Since there hasn’t been much success with hybridized bananas, GMO bananas have become the focus of a few researchers, without much support from the banana producing industry, like Dole.
Enter GMO bananas
Soon after the new TR4 fungal disease was discovered, scientists were trying to find a way to keep it at bay so that we could continue to have bananas for breakfast. Banana farmers in Malaysia and Indonesia reported that there was a subspecies of Musa acuminata, called Lady Finger bananas, that were growing well in plantations that had been destroyed by the TR4 fungus. Although Lady Finger bananas are not generally available in the USA and Europe because of transportation issues, the cultivar is very popular in Southeast Asia and Australia.
So the first thing that the scientists had to do was isolate the gene responsible for TR4 resistance in the Lady Finger subspecies. In 2004, the lab of James Dale, a professor of biotechnology at Queensland University of Technology in Australia, identified possible genes that could be tested for resistance to the fungus. As an aside, Dr. Dale is also working on a “golden banana,” with vitamin A, that could be a boon to the health of children all over the world in the same way as golden rice.
Over the next three years, Dale’s lab inserted genes from the Lady Finger bananas into cells from the Cavendish banana. At first, the new plants grew in test tubes, before growing into whole plants that could be placed in the soil. Despite the dangers of TR4 to the Cavendish plantations worldwide, most growers weren’t worried about the fungus, because they thought they could control the disease through a novel fungicide or quarantines.
As a result, Dale couldn’t get funding to do a field trial of his new GMO bananas. But a few more years of unsuccessful prevention of the spread of TR4 lead to a little funding, and Dale was able to plant a small field trial in 2012. The study lasted three years, after which Dale’s lab reviewed the results.
The outcomes from this initial trial were described to be “extremely positive” by Dale. Four out of six plant lines planted showed resistance to TR4 after it was introduced to the plant. Based on these initial results, Dale intends to expand the field trial to thousands of plants, planted over three years. Not only does Dale need to confirm the TR4 resistance, but also he needs to determine if yield is significantly different or whether the plants need special attention that would make it harder to cultivate. Of course, they need to confirm that the characteristics that make the Cavendish so popular are retained in the GMO bananas.
Right now, Dale’s research on GMO bananas is almost the only hope that science has to making the Cavendish cultivar resistant to TR4 without changing the other characteristics, like taste, texture, and transportability.
Regrettably, Dale is one of the very few researchers looking into GMO bananas for resistance to TR4. The major banana producers, such as Dole, don’t appear to be concerned, possibly because their plantations in Latin America have not been affected by the fungus – as of today. Inevitably, the fungus will cross the Atlantic and Pacific, as a result of all kinds of unforeseen consequences, and destroy the banana plantations in the Americas. And then, we won’t be eating bananas, unless Dale’s research comes to fruition.
GMO bananas – the summary
Right now, there appears to be an impending disaster approaching our sources of bananas worldwide. Except in the short-sighted minds of the Big Banana corporations, who seem to think techniques that haven’t worked so far in preventing the fungus from spreading will obviously work for them.
A research lab in Australia appears to have bioengineered GMO bananas that will confer resistance against the banana killing fungus. More research will be required, along with the inevitable battle with anti-science radicals like Greenpeace, before we see this new banana in widespread use.
I hope this all works out. I don’t want to experience never tasting another banana again sometime in the future. Or need to pay extraordinary amounts of money to have one.
We have hope in these bioengineered bananas.
- Paul JY, Becker DK, Dickman MB, Harding RM, Khanna HK, Dale JL. Apoptosis-related genes confer resistance to Fusarium wilt in transgenic ‘Lady Finger’ bananas. Plant Biotechnol J. 2011 Dec;9(9):1141-8. doi: 10.1111/j.1467-7652.2011.00639.x. Epub 2011 Aug 7. PubMed PMID: 21819535.