Genetically modified banana could prevent a global crop collapse

In a small plot in the Northern Territory, banana plants have thrived for almost a decade in soil that should kill them.

According to those who have tried the fruit, they taste exactly like a banana should.

But the plants near Humpty Doo have a secret hiding in their DNA: a genetic modification that protects bananas from a disease that is on the verge of wiping out crops around the world.

James Dale, an agricultural biotechnology researcher at the Queensland University of Technology, helped develop the disease-resistant banana — the world's first genetically modified banana to be approved in Australia.

He said there were no regulatory hurdles stopping the bananas, called QCAV-4, from entering the market.

"If we saw them in the Northern Territory in 2027, that would be wonderful."

After that, the rest of the world might not be far behind if a major hurdle can be overcome: convincing consumers to eat the genetically modified fruit.

So how can tweaks to a banana's genetic blueprint make it resistant to a deadly disease? And what would set it apart from genetically modified food already on the supermarket shelf?

What is Panama disease or TR4?

The reason for developing QCAV-4 is a fungus called Tropical Race 4, also known as TR4, a strain of the banana-infecting Panama disease.

Growers are well aware of signs of infection. Outward symptoms start with the banana plant's leaves beginning to wilt and go yellow.

Meanwhile, inside the plant, a fungus called Fusarium oxysporum is climbing from the plant's roots up the stem in an ominous red ring.

To attempt to stop the spread, the plant will try to build blocks to stop the fungus spreading, but this leads to the plant also obstructing the movement of water and nutrients, effectively starving itself to death.

The TR4 strain of Panama disease was first detected in Taiwan in the 1960s. 

Despite being spread through soil, not through the bananas, dozens of countries have already seen the fungus arrive on their shores, including Australia.

In some areas, major quarantine measures can slow its spread, but once Panama disease arrives, it is extremely hard to continue growing bananas in infected soil.

Spores can survive in the soil for decades even without banana plants, and it is impossible to eradicate once it has taken hold. 

For Leon Collins, a banana grower in the Tully Valley in Queensland and chair of the Australian Banana Growers' Council, Panama disease is the biggest issue banana growers currently face.

"You'll have a plant down the bottom end of the paddock [get infected], and the next one will be at the top."

Farmers with Panama disease on their land must destroy infected plants and avoid tracking soil from one plantation to the other. Many farmers stop growing bananas altogether, and try their luck with another crop.

But despite impressive quarantine measures, even Mr Collins admits that Queensland banana growers cannot keep the fungus at bay forever.

How genetic modification makes bananas resistant to Panama disease

Professor Dale has been working on producing a genetically modified Cavendish banana resistant to the TR4 strain of Panama disease for more than 20 years.

With QCAV-4 — the fourth iteration of the genetically modified fruit — the QUT team has succeeded.

The Cavendish banana contains a gene called MamRGA2 from the wild, South-East Asian banana, Musa acuminata ssp malaccensis.

The new gene produces proteins that help the plant cells detect the presence of the fungus arriving, quickly triggering its defence response and preventing infection from taking hold.

These resistance proteins swing into action in a similar way to mammal's immune cells, and according to Professor Dale, leads "to a cascade of defence mechanisms" including producing chemicals, enzymes and even programmed cell death to protect the larger whole. 

Like all commercial banana plants, QCAV-4 is grown from offshoots, not seeds, and so the risk of the genetically modified plants travelling outside their planted area is extremely low.

Last year, QCAV-4 gained regulatory approval, making it the first genetically modified fruit approved by the federal government to be grown in Australia.

Not long after, the research team behind QCAV-4 gave it a taste test.

Then external growers who flew to the Northern Territory to try the bananas confirmed what the team suspected, Professor Dale said: "They tasted as good as any well-grown Cavendish."

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Mark Smith, the farm manager at Darwin Fruit Farms in Humpty Doo, has seen the genetically modified banana plants in action.

Darwin Fruit Farms — the Northern Territory's only commercial banana grower — is where trials into QCAV-4 have taken place.

The trials were done there because the soil is heavily infected with Panama disease and Mr Smith must undertake stringent practices to be able to grow any bananas at all.

QCAV-4 banana plants have been growing at the farm for more than seven years, which dwarfs the 18-month turnover for standard Cavendish bananas in fungus-infected soil.

But although he sees the potential in growing disease-resistant bananas, he's not yet convinced on planting QCAV-4 commercially.

"We could expand, which would make a big difference," he said.

"But I don't think there's been enough work on growing [QCAV-4 on a larger scale] because there just hasn't been that many available."

Will people eat genetically modified bananas?

According to Professor Dale, the Northern Territory could be one of the first places in the world to have QCAV-4 on supermarket shelves.

"I think [the NT] would be the best place to start because growers up there could supply the Darwin market at a much lower price than they're currently getting their bananas," he said.

"And price is a big motivation for consumers."

But Darwin Fruit Farms manager Mr Smith is wary of how consumers will react to a genetically modified product.

"If there's nothing else you'd buy them, but … people are a bit funny about genetics and modification," he said.

Genetically modified foods are already on Australian shelves, but they are mostly ingredients such as canola oil or wheat flour.

While these products only need to highlight their genetically modified status on the back in the ingredients list, QCAV-4 would need to predominantly display that it is a genetically modified product.

"Most of the western world — Europe, and I'm pretty sure Australia — would not be too happy about having advertised genetically modified bananas," Mr Smith said.

A Food Standards Australia and New Zealand consumer survey report from 2022 backs up this view, with almost half of respondents indicating some level of concern about genetically modified foods.  

This hesitancy has meant that the Australian Banana Growers' Council have continued to reiterate that there are "no plans to commercialise in Australia, yet".

But that hesitancy seems to be starting to fade. With newer trials by the team testing QCAV-4 in North Queensland, and a clear market in the Northern Territory, it may only be a matter of time before QCAV-4 ends up on shelves.

Internationally, Professor Dale said the positive response from farmers to QCAV-4 bananas was even stronger.

"We're got a number of growers over in Central and South America who are very interested in our program because they're very concerned about the future of bananas," he said.

The team has started a trial in the Philippines, which is one of the world's largest banana-growing nations, but is struggling to contain the spread of the fungus. 

For QCAV-4, with no more regulatory approvals required, and farmers keen to get their hands on the plants, the final hurdle — according to Professor Dale — is just to convince people to eat them.