Science

Tackling the fungi that could wipe out the world's banana supply within a decade

Tackling the fungi that could ...
A three-fungus disease complex threatens to wipe out the world's banana crops within the next decade
A three-fungus disease complex threatens to wipe out the world's banana crops within the next decade
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A three-fungus disease complex threatens to wipe out the world's banana crops within the next decade
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A three-fungus disease complex threatens to wipe out the world's banana crops within the next decade
Ioannis Stergiopoulos, plant pathologist at UC Davis, is leading the research
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Ioannis Stergiopoulos, plant pathologist at UC Davis, is leading the research

A staple of grocery store bins and household fruit bowls around the world, you might be forgiven for assuming the humble, ubiquitous banana would be around forever. But evolving fungal diseases are threatening the global banana industry, and a total "bananageddon" could wipe out the fruit within a decade. Researchers at University of California, Davis (UC Davis) have sequenced the genomes of the fungi to find a way to fight back.

The most common type of banana the western world eats is the Cavendish, which is produced through vegetative reproduction – instead of growing from seeds, cuttings of the plant's shoots are replanted and cultivated, making all Cavendish bananas essentially "clones" of one specific plant. Without genetic variety, as diseases gain a foothold over the fruit, they're equipped to potentially take out the entire worldwide crop.

"The Cavendish banana plants all originated from one plant and so as clones, they all have the same genotype – and that is a recipe for disaster," says Ioannis Stergiopoulos, plant pathologist at UC Davis.

Currently, close to 120 countries produce about 100 million tons of bananas each year, but 40 percent of the yield is spoiled by Sigatoka, a fungal disease complex comprised of three strains: yellow Sigatoka, black Sigatoka and eumusae leaf spot. To combat the ever-present threat, farmers need to apply fungicide to their crops 50 times a year, which isn't only costly, but can pose a threat to the environment and human health.

"Thirty to 35 percent of banana production cost is in fungicide applications," says Stergiopoulos. "Because many farmers can't afford the fungicide, they grow bananas of lesser quality, which bring them less income."

The Cavendish variety rose to market prominence in the second half of the 20th century after the previously ubiquitous species, the Gros Michel, was all but wiped out by a similar fungus, Panama disease. To try to prevent a similar bananapocalypse, Stergiopoulos and the UC Davis team set about sequencing the genome of the fungi to determine how it attacks its hosts and, hopefully, how it can be overcome.

Ioannis Stergiopoulos, plant pathologist at UC Davis, is leading the research
Ioannis Stergiopoulos, plant pathologist at UC Davis, is leading the research

With the genome of yellow Sigatoka already sequenced, the team did the same for the other two diseases, then compared the results of all three. It was found that the fungi not only shuts down the host plant's immune system, but adapts its own metabolism to match that of its host, allowing it to produce enzymes that break down the cell walls and release the sugars and carbohydrates for it to feed on. Armed with that knowledge, the team hopes that further research will lead to a solution.

"This parallel change in metabolism of the pathogen and the host plant has been overlooked until now and may represent a 'molecular fingerprint' of the adaption process," says Stergiopoulos. "It is really a wake-up call to the research community to look at similar mechanisms between pathogens and their plant hosts."

The research was published in the journal PLOS Genetics.

Source: UC Davis

2 comments
Growling_M.A.D+Dirty
Well better go to it lads. Begin all over again. Take a wild banana and start breeding it towards the results a Cavendish banana gives the producers. Hopefully the natural mutations that have been going on for the last 200 years will avert the fungi. Or not. Then the world population have to live without bananas. People lived for thousands of years without bananas until we started shipping and breeding them for aristocratic then common consumption. The banana companies have to look broader on what their core business is, really. It is not bananas, it is sweet fruits for the masses.
bobcat4424
Actually "bananageddon" has already happened once before to the Gros Michel banana which was the staple before the Cavendish. The Gros Michel was wiped out buy the Panama Disease, a fungus. The world basically went ten years without bananas until the Cavendish was developed. (Bananageddon was the reason for the song, "Yes, We Have No Bananas.") The basic problem is that cloning is the only way to produce a product that remains true. Cross-bred bananas tend to revert in successive generations.