Coffee Wilt Fungus Gains New Abilities Through Genetic Theft

Outbreaks of coffee wilt disease have been linked to the fungus responsible repeatedly acquiring DNA segments from a related fungal pathogen. These findings, reported in the journal PLOS Biology by Lily Peck of Imperial College London, shed new light on the disease’s history and evolution.

The fungal pathogen Fusarium xylarioides causes coffee wilt disease, which has devastated coffee production across sub-Saharan Africa for over a century. Despite being identified in 1927, its genetic makeup and evolutionary history remain poorly understood—key knowledge for controlling future outbreaks.

In a new study, researchers analyzed the genomes of 13 historical strains of F. xylarioides collected over six decades and multiple outbreaks. Their findings reveal at least four distinct lineages of the pathogen:

• Two historical lineages infecting various coffee species,
• One lineage specialized for arabica coffee, and
• One adapted to robusta coffee.

The team also uncovered evidence of horizontal gene transfer (HGT), where DNA segments from Fusarium oxysporum, another fungal pathogen, were repeatedly incorporated into F. xylarioides. These genetic additions likely enhanced its ability to infect coffee plants and may have driven the recurrent outbreaks of coffee wilt disease across Africa.

Similar horizontal gene transfer events have been implicated in the emergence of other pathogens, such as Aspergillus fumigatus (which infects immunocompromised individuals), potato blight, and certain wheat fungal diseases.

The researchers emphasize that applying genomic techniques to historical fungal strains stored in culture collections could be a powerful tool for understanding the role of HGT in pathogen outbreaks.

The authors concluded, “A historical approach shows the importance of horizontal transfers and large mobile elements in the emergence of new types of disease. If we can understand how new types of diseases evolve, we can give growers the knowledge they need to reduce the risk of new diseases emerging in the first place.”