Biology

Genetically modified bananas out to stop Cavendish catastrophe

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Regulatory appeal: A genetically modified, disease-resistant Cavendish banana plant could soon be commercially approved
Regulatory appeal: A genetically modified, disease-resistant Cavendish banana plant could soon be commercially approved
QUT's James Dale with grown QCAV-4 banana plants, at the QUT facility in the Northern Territory
QUT
From left: The wild banana plant, the Cavendish plant and the QCAV-4 banana plant
QUT
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It’s been more than 50 years since the lethal soil-borne Fusarium fungal species all but wiped out the dominant Gros Michel banana across the globe. Now, though, the tropical race 4 (TR4) strain of the fungus threatens to repeat history, potentially killing off the world’s most popular and widespread variety, the Cavendish, and with it a US$20 billion banana industry.

However, for the past 20 years, scientists at the Queensland University of Technology (QUT) in Australia have been developing a genetically modified Cavendish banana plant that isn't impacted by the fungus, also known as Panama disease. After earlier studies into the disease-resistant gene RGA2, the researchers spent more than six years growing the modified fruits in field trials in the Northern Territory. The result has been plants growing Cavendish bananas as we know them, but ones that are also highly resistant to the TR4 fungus.

They’ve now submitted their modified Cavendish banana variety, known as QCAV-4, to the Food Standards Australia New Zealand (FSANZ) for regulatory approval. The assessors will look at molecular, chemical, compositional and nutritional aspects of the disease-resistant QCAV-4. The process is expected to take around nine months, and if successful it will be the country’s first whole genetically modified fruit and the world’s first GM Cavendish plant.

From left: The wild banana plant, the Cavendish plant and the QCAV-4 banana plant
QUT

“The devastating Panama disease TR4 is caused by a soil-borne fungus that stays in the ground for more than 50 years, wiping out banana crops and destroying farms for generations,” said James Dale, professor at QUT, also known as the "banana man" for his commitment to their genetic science. “It is a huge problem. It has devastated Cavendish plantations in many parts of the world and could cripple the Cavendish banana export industry worldwide.”

While there are around 1,000 varieties of bananas grown across the globe’s tropical regions, the Cavendish makes up around half of all types cultivated and almost 100% of international trade.

What makes the variety particularly vulnerable is that it can’t reproduce sexually, which is nature’s way of maintaining genetic diversity. As such, it’s propagated, essentially creating identical clones of the plants, greatly limiting its genetic makeup and making it incredibly susceptible to widespread devastation from a single pathogenic invader.

And in this case, Fusarium oxysporum f.sp. cubense (Foc) has the potential to wipe out the Cavendish variety. First detected in Asia, it’s since spread to most Cavendish-producing regions including recent infections in Colombia and Peru.

The fungus enters the plant through its roots and sets up shop in the xylem vessels, responsible for transporting and distributing water and nutrients. Eventually, the plant wilts (which is why the disease is also called Fusarium wilt) and dies. And once it’s in the crop’s soil, it can’t be eradicated with pesticides.

QCAV-4 has been bioengineered with the single gene RGA2, which stems from a southeast Asian wild banana plant that’s shown to be resistant to TR4 infection. While the Cavendish bananas already have this gene, it’s dormant; its activation appears to be crucial to its ability to fight off the fungus foe.

QUT's James Dale with grown QCAV-4 banana plants, at the QUT facility in the Northern Territory
QUT

While still a long way from commercial production and consumption, its approval could provide a safety net for the fruit, seeing it avoid the same fate as the Gros Michel.

Earlier research on the QCAV-4 was published in a 2017 issue of the journal Nature Communications.

See the video below to see more on the fungal threat and the QCAV-4 banana plant journey.

Source: Queensland University of Technology

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7 comments
bobcat
I am an old guy (79) so I remember the taste of Gros Michel bananas because they are the banana when I was a kid. First came a "banana famine" when bananas because too expensive for working class families when the fungus started destroying crops. Then the Cavendish came along. The first thing one noticed is that they were picked green and artificially ripened. The second thing you noticed was that they tasted more like plantains than the Gros Michel banana. At the time, they were described as tasing exactly like a green plantain -- similar to damp cardboard. People have become used to the tasteless Cavendish. But a genetically-engineered version is very likely to be even more tasteless and bland.
TechGazer
bobcat beat me to it. I too remember when bananas (Gros Michel) actually tasted good. Please genetically engineer the Gros Michel so people can enjoy it again.
Charles Rader
For bobcat: Why would a genetically modified Cavendish banana be even more tasteless? This sounds like you begin with a suspicion of the genetic modification technology before you have any evidence about it one way or another. Given that the Queensland University of Technology team worked on this project for twenty years, they surely had some interest in preserving the taste characteristics of the Cavendish.
Edward Vix
TechGazer, exactly what I was thinking, yes, back to Gros Michel, now that would be something! If they're not doing that it's likely that it might not be as profitable, and if that's the case they'll never bother.
stevendkaplan
Why didn’t they just use the tech to make the Gros Michel resistant to whatever it was that caused it to start dying out, plus give it resistance to this new fungus? From what I understand the Gros Michel tastes better than Cavendash.
KaiserPingo
So nobody with just minor intelligence learnt from the problem with mono-culture?
And now going to bed with a company, just continues the trend, but making it worse?
Well, thats greed as we know it.
anthony88
Carnarvon Bananas are a nice alternative. Not sure if they're Cavendish grown in a different location, but they're sweeter, and they aren't too big. Not sure if they're exported beyond the West Australian border.