~SUSTAINABLE LIVING FOR CHALLENGING TIMES

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The banana is dying. The race is on to reinvent it before it's too late

The world's most popular fruit is facing extinction, and scientists are racing to use gene-editing to save it. To succeed, they'll need to overcome an even bigger problem: opposition to GMO crops

By Matt Reynolds
Thursday 11 October 2018


A TR4-infected banana plantation near Darwin, Australia. To try and prevent its spread, the region is subject to bio-quarantine rules. Credit: Jeff Daniels

The Cavendish hasn’t always been popular. Before the 1950s, Europe and America’s banana of choice was the Gros Michel – a creamier, sweeter banana that dominated the export market. Unlike the Cavendish, which needed to be transported in boxes to protect its fragile skin, the robust and thick-skinned Gros Michel was ideally suited to long, bumpy journeys across the Atlantic. At the time, the thin-skinned and slightly bland Cavendish was seen as a second-rate banana.

However, Gros Michel had one weakness. It was susceptible to Tropical Race 1 (TR1), an earlier strain of the Fusarium fungus. TR1 was first detected in Latin America in 1890 and, in the 60 years that followed, it tore through banana plantations in Latin America, costing the industry $2.3 billion in today’s terms. Faced with no other choice, the major banana firms switched production to their backup banana: the Cavendish. In 1960, the world’s biggest banana exporter, United Fruit Company (now called Chiquita) began switching to the Cavendish, following the lead of its smaller rival, Standard Fruit Company (now called Dole) which switched in 1947. Despite all its shortcomings, the Cavendish had one huge advantage over the Gros Michel, which disappeared from US supermarket shelves forever in 1965: it was completely resistant to TR1.

But the Cavendish has no defence against TR4. When Ploetz first encountered the new pathogen, there had been just a handful of suspected infections reported. In 1992, Ploetz received packages containing TR4 from plantations in Indonesia and Malaysia. “At the time all we knew was that it was a new pathogen,” he says. “We didn’t know what to expect as far as its broader implications. The more samples we got from these export plantations, the more we began to realise that this was a bigger issue than we had ever anticipated,” he recalls. His prediction proved to be eerily accurate.

In 2013, TR4 was found for the first time in Mozambique. Ploetz thinks it had been carried on the boots and equipment of banana planters from southeast Asia. The pathogen has now travelled to Lebanon, Israel, India, Jordan, Oman, Pakistan and Australia. In 2018, it was found in Myanmar. “Then in southeast Asia,” Ploetz says. “It’s everywhere.”

When TR4 hits, the destruction is near-total. “It looks like somebody’s gone to the plantation with a herbicide,” Ploetz says. “There are big areas that no longer have any plants at all.” The fungus, which can live undetected in the soil for decades, enters banana plants through their roots and spreads to the water- and nutrient-conducting tissue within, eventually starving the plant of nourishment. Two to nine months after being infected, the plant – hollowed out from the inside – collapses in on itself. The soil it grew in, now riddled with the fungus, is useless for growing bananas.

As TR4 creeps across the globe towards Latin America, the Cavendish’s genetic uniformity is starting to look like a curse. Ploetz estimates that TR4 has already killed more Cavendish bananas than Gros Michel plants killed by TR1, and, unlike the previous epidemic, there is no TR4-resistant banana ready to replace the Cavendish. And time to find a solution is rapidly running out. “The question is, ‘when is it going to come over here?’,” Ploetz says. “Well, it may already be here.”

So far, Latin America, which grows almost all of the world’s export bananas – including those for the US and Europe – has escaped TR4. But, Ploetz says, it’s only a matter of time. “Our concern in Central America is that if somebody has an outbreak on their property, they are going to keep their mouths shut, and then it’ll have spread widely by the time people realise it’s there,” he says.

Faced with a crisis that could see the Cavendish gone forever, a handful of researchers are racing to use gene-editing to create a better banana and bring the world’s first TR4-
resistant Cavendish to the market. To get there, they will butt up against not only the limitations of technology, but resistance from lawmakers, environmentalists and consumers wary of GM crops. But as TR4 closes in on Latin America, gene-editing may be the last chance we have to save the one banana we have chosen above all others.

Continues below:

https://www.wired.co.uk/article/cavendish-banana-extinction-gene-editing