A “bananageddon” might be on the horizon, and not for the first time. But new research could help save our favorite fruit.
The bananas we chow down on nowadays mostly belong to the Cavendish variety, but they’re facing an existential threat. A fungus called Foc TR4 is infecting and killing off crops with a disease called fusarium wilt, and once it takes hold in a banana field it’s almost impossible to eradicate. Worse still, Cavendish bananas the world over are essentially clones, so every last one is vulnerable – there’s no genetic diversity that could help some pockets survive.
As such, there’s a very real possibility that the banana as we know it could go functionally extinct. If that sounds unbelievable, it’s actually happened before.
“The kind of banana we eat today is not the same as the one your grandparents ate,” said Li-Jun Ma, senior author of the study. “Those old ones, the Gros Michel bananas, are functionally extinct, victims of the first Fusarium outbreak in the 1950s.”
Ironically, Cavendish bananas actually took over because of their natural resistance to the fungal strain that wiped out the Gros Michel. But now, over the past few decades a different strain has come back to finish the job. For the new study, researchers at the University of Massachusetts Amherst investigated the genome of the fungus to try to find some clues that could help fight it.
“We have spent the last 10 years studying this new outbreak of banana wilt,” said Ma. “We now know that the Cavendish banana-destroying pathogen TR4 did not evolve from the race that decimated the Gros Michel bananas. TR4’s genome contains some accessory genes that are linked to the production of nitric oxide, which seems to be the key factor in TR4’s virulence.”
Nitric oxide is harmful to the bananas, and it seems that the fungus releases a burst of this gas to overwhelm the fruit’s immune system, giving the fungus time to infect it. Sure enough, when the scientists removed two genes that control nitric oxide production, the virulence of the fungus was greatly reduced.
Hopefully, this could lead to new ways to reduce or control the spread of the disease, and save the world from another bananapocalypse. Other scientists are also genetically engineering Cavendish bananas to be more resistant to the fungus.
The research was published in the journal Nature Microbiology.
Sources: University of Massachusetts Amherst, The Conversation
