Fungi may cause bananas to go extinct in 5 to 10 years

Drenth also said more monitoring around banana plantations, and molecular diagnostic tests to determine the fungal disease should be carried out frequently to ensure that the disease doesn’t recur in Australia.

The threat could be coming from something called the Sigatoka complex, made up from three fungal diseases, which pose a huge risk to the world’s banana supply.

Plant pathologist Ioannis Stergiopoulos explained: “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 path ways and make use of its nutrients”.

Though there are clear implications for smoothie lovers, the effects of a banana shortage would most severely impact countries that rely on bananas as a staple food.

Stergiopoulos analysed the fungal attack when he sequenced the genomes of black Sigatoka and eumusae leaf spot, and then compared the results with the earlier sequenced yellow Sigatoka genome. Of the three, black Sigatoka poses the greatest risk to bananas grown annually in nearly 120 countries. But the fruit suffers from an image problem, giving consumers the appearance that it is and always will be readily available, said Stergiopoulos.

The researchers noted that although yellow sigatoka was the first of the three closely related fungal pathogens to be recorded on banana, but the other two of these, namely eumusae leaf spot and black sigatoka, are now the most devastating. 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 per cent of banana production cost is in fungicide applications”, he said.

The Australian Banana Growers Council said more than five million bananas are consumed by Australians daily.

While many people likely think that bananas will be around forever, that definitely isn’t the case. And unlike a tomato or green bean, which are grown from seeds, bananas are grown from shoot cuttings.

‘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. 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. Similar trials to develop fungus-resistant banana plants are under way in other laboratories, using other approaches.

Financial support for the study was provided by UC Davis faculty startup funds.