If we're not careful, the banana could suffer the same fate as the dodo. Recent estimates predict that the global banana industry could suffer a total collapse in as little as 5 years time due to a feisty fungal disease. But there is some hope – genetic scientists have been tirelessly working on the problem in a bid to understand this fungus and save the humble banana from ruin.
The banana's plight stems from three strains of Sigatoka fungal disease, which destroys the banana plant's leaves and can rip through whole plantations. It’s advancing at such a rate, the global banana industry could be crushed in 5 to 10 years time if the situation remains the same.
The most common variety of banana you’ll find in the grocery store is the Cavendish banana. Unlike many plants, they’re grown from shoot cuttings of other bananas, not seeds. This means that all Cavendish bananas are clones that have the same genotype. Therefore, they all share the exact same susceptibility to diseases, allowing them to spread like wildfire.
Fortunately, scientists from University of California, Davis, might have warded off the “banana armageddon” by studying the genetics of the fungi. Their findings are published in the online journal PLOS Genetics.
“We have demonstrated that two of the three most serious banana fungal diseases have become more virulent by increasing their ability to manipulate the banana’s metabolic pathways and make use of its nutrients,” said lead researcher Ioannis Stergiopoulos, a plant pathologist from UC Davis.
“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,” he said. “It is really a wake-up call to the research community."
Effects of the devastating black Sigatoka fungus in Quindió, Colombia. Neil Palmer/CIAT/Flickr (CC BY-SA 2.0)
For the first time, they have managed to sequence the genomes of all three Sigatoka strains: yellow Sigatoka, eumusae leaf spot, and black Sigatoka.
“Now, for the first time, we know the genomic basis of virulence in these fungal diseases and the pattern by which these pathogens have evolved,” said Stergiopoulos.
They discovered that the complex of diseases first shuts down the plant’s immune system and changes the metabolism of the fungi to match that of the host. It then produces enzymes to break down the cell walls so it can feed off the plant’s carbohydrates.
More research needs to be done, but our increasing knowledge of the fungal diseases could mean the banana’s doom may just be averted.