USA – Bananas, one of the world’s most popular fruits, are at risk of functional extinction due to a fungal disease known as Fusarium wilt of banana (FWB), or Panama disease.
This disease is caused by the pathogen Fusarium oxysporum f.sp. cubense (Foc), specifically the tropical race 4 (TR4) variant.
However, new research from the University of Massachusetts Amherst has identified “accessory genes” within the fungus that may hold the key to combating the disease.
The current strain of Panama disease is a significant threat to the Cavendish variety of bananas, which dominate global commercial production. This variety was introduced after the Gros Michel banana, previously the world’s favorite, was wiped out by an earlier strain of the same disease in the 1950s.
The Cavendish has been the mainstay of the banana industry since then, but in the 1990s, TR4 began decimating Cavendish plantations across Southeast Asia, Africa, and Central America.
Professor Li-Jun Ma, a biochemistry and molecular biology expert at UMass Amherst, has been leading research on this deadly fungus. Her team’s findings reveal that TR4 did not evolve from the earlier strain that destroyed the Gros Michel bananas.
Instead, TR4’s genome includes specific accessory genes that produce nitric oxide, which contributes to the fungus’s ability to cause wilting in banana plants.
These accessory genes appear to be a crucial factor in the pathogen’s virulence. By comparing 36 strains of the fungus worldwide, including those responsible for past banana extinctions, the researchers demonstrated that these genes enable the fungus to attack banana plants more effectively.
Intriguingly, when the genes responsible for nitric oxide production were removed, the severity of the disease was significantly reduced.
Lead author Yong Zhang of the Organismic and Evolutionary Biology program at UMass Amherst suggests that understanding how these accessory genes work could open up new avenues for controlling the spread of TR4.
While the discovery is promising, the researchers emphasize that further investigation is needed to fully grasp how nitric oxide production leads to disease infestation.
Despite this breakthrough, Ma warns that monoculture farming practices, where the same crop is grown year after year on the same land, are still the biggest threat to banana crops.
The lack of genetic diversity in vast commercial plantations makes them easy targets for pathogens like TR4.
“Next time you’re shopping for bananas, try different varieties in your local specialty foods store,” Ma advises, encouraging consumers to support biodiversity in the banana industry.
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