The bananas we commonly find in supermarkets, especially the Cavendish variety, are facing a dire threat of functional extinction due to a disease known as Fusarium wilt of banana (FWB), caused by a fungal pathogen. Specifically the fungus is Fusarium oxysporum f.sp. cubense (Foc) tropical race 4 (TR4). Recent research led by an international team from the University of Massachusetts Amherst has shed light on this pathogen, revealing that Foc TR4 did not evolve from the strain responsible for the Gros Michel banana’s demise in the 1950s. Instead, the virulence of TR4 is linked to specific accessory genes associated with nitric oxide production, which plays a crucial role in the pathogen’s ability to infect and damage banana plants.
This groundbreaking study, published in Nature Microbiology[3], opens the door to potential treatments and strategies to mitigate the spread of Foc TR4, which remains unchecked in many regions. Li-Jun Ma, a professor of biochemistry and molecular biology at UMass Amherst and the paper’s senior author, emphasizes that the bananas we consume today are not the same as those eaten by previous generations. The Gros Michel variety, once dominant, is now functionally extinct due to the first outbreak of Fusarium wilt. In response, the Cavendish banana was bred to be disease-resistant and has become the most widely cultivated banana variety, accounting for nearly all commercial banana exports.
However, by the 1990s, Cavendish bananas began to face their own challenges as TR4 spread from Southeast Asia to Africa and Central America, threatening the global banana supply. The research team, including lead author Yong Zhang, spent over a decade studying this new outbreak of banana wilt. They sequenced and compared 36 different Foc strains from around the world, discovering that TR4 possesses unique accessory genes that facilitate its virulence. These genes are involved in both the production and detoxification of nitric oxide, which aids in the pathogen’s invasion of banana plants. Notably, the virulence of Foc TR4 was significantly diminished when two specific genes controlling nitric oxide production were removed, highlighting potential targets for future treatments.
Despite these promising findings, Ma warns that monocropping practices exacerbate the vulnerability of banana crops to diseases like FWB. The lack of genetic diversity in large-scale banana plantations makes them easy targets for pathogens. She encourages consumers to explore different banana varieties available in specialty stores to promote biodiversity in banana cultivation.
Funding for this significant research was provided by various U.S. government agencies, including the National Science Foundation and the Department of Agriculture, as well as international partners, underscoring the collaborative effort to address this critical agricultural challenge.
For further reading on the impact of Fusarium wilt on banana production, check these sources:
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[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829247/
[2] https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01468/full
[3] https://www.nature.com/articles/s42003-023-04417-w
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6459961/
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9498937/
[6] https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0273335
[7] https://www.popsci.com/environment/bananas-extinction/
[8] https://www.miragenews.com/umass-biologists-may-save-bananas-from-1297535/