News

Bananapocalypse – the tricky genetics of a devastating fungus

Li-Jun Ma
By Li-Jun Ma
Nov. 9, 2024

Did you know that the bananas you eat today are not the same type as the ones people were eating a few generations ago? The banana you might have had with your breakfast today is a variety called the Cavendish banana, while the one that was in grocery stores up to the 1950s was a variety called Gros Michel, which was wiped out by a disease called Fusarium wilt of banana, or FWB.

FWB of Gros Michel was caused by Fusarium oxysporum race 1, a fungal pathogen that affects bananas. This fungal infection kills a plant by occupying its vascular system, blocking water and mineral transportation.

Fusarium oxysporum spores can remain hardy in soil for decades.

Plant biologists developed the Fusarium-resistant Cavendish variety to replace the Gros Michel. Yet, over the past few decades, a resurgence of FWB caused by a different strain of the same fungus called tropical race 4, or TR4, is once again threatening global banana production.

How did Fusarium oxysporum gain the ability to overcome resistance and infect so many different plants?

You would be hard-pressed to find a Gros Michel banana in American supermarkets today.
You would be hard-pressed to find a Gros Michel banana in American supermarkets today.

The two-part genome of F. oxysporum

I am a genomicist who has spent the past decade studying the genetic evolution of Fusarium oxysporum. As a species complex, F. oxysporum can cause wilt and root rot diseases in over 120 plant species. Certain strains can also infect people.

In 2010, my lab discovered that each F. oxysporum genome can be divided into two parts: a core genome shared among all strains that codes for essential housekeeping functions, and an accessory genome varying from strain to strain that codes for specialized functions like the ability to infect a specific plant host.

Each species of plant has a sophisticated immune response to defend against microbial invasion. So to establish an infection, each F. oxysporum strain uses its accessory genome to suppress a plant’s unique defense system. This functional compartmentalization allows F. oxysporum to greatly increase its host range.

The genomic structure of Fusarium oxysporum allows it to have a wide range of hosts, such as tomatoes, cucumbers and watermelon.
The genomic structure of Fusarium oxysporum allows it to have a wide range of hosts, such as tomatoes, cucumbers and watermelon.

In our newly published research, my team and colleagues in China and South Africa found that the TR4 strain that kills Cavendish bananas has a different evolutionary origin and different sequences in its accessory genome compared with the strain that killed Gros Michel bananas.

Looking at the interface of where the TR4 strain is battling with its Cavendish banana host, we found that some of its activated accessory genes release nitric oxide, a gas harmful to the Cavendish banana. This sudden burst of toxic gases facilitates infection by disarming the plant’s defense system. At the same time, the fungus protects itself by increasing production of chemicals that detoxify nitric oxide.

Increasing banana diversity

In tracing the global spread of this new version of Fusarium oxysporum, we realized that a major cause for the recent resurgence of this fungal infection is the domination of the international banana industry by a single clone of banana.

Growing different varieties of bananas can make agriculture more sustainable and reduce disease pressure on a single crop. Farmers and researchers can control Fusarium wilt of banana by identifying or developing banana varieties that are tolerant or resistant to TR4. Our findings suggest that another way to protect Cavendish bananas would be to design effective nitric oxide scavengers to reduce the toxic pressure of the gas burst.

The banana industry has dark origins.

It can be hard to imagine how a consumer who simply enjoys eating bananas could participate in the battle against the disease devastating banana crops. However, consumers determine the market, and farmers are forced to grow what the market demands.

You can help increase banana diversity in your supermarket by intentionally trying one or more of the other hundreds of other existing banana varieties when they show up there. You can also buy local varieties of other fruits and agricultural products to help preserve plant diversity and support local growers.

Collaboration among scientists, farmers, industry and consumers around the world can help avoid future shortages of bananas and other crops.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Conversation

Enjoy reading ASBMB Today?

Become a member to receive the print edition four times a year and the digital edition monthly.

Learn more
Li-Jun Ma
Li-Jun Ma

Li-Jun Ma is a professor of Biochemistry and Molecular Biology, UMass Amherst.

Get the latest from ASBMB Today

Enter your email address, and we’ll send you a weekly email with recent articles, interviews and more.

Latest in Science

Science highlights or most popular articles

How sugars shape Marfan syndrome
Journal News

How sugars shape Marfan syndrome

Sept. 10, 2025

Research from the University of Georgia shows that Marfan syndrome–associated fibrillin-1 mutations disrupt O glycosylation, revealing unexpected changes that may alter the protein's function in the extracellular matrix.

What’s in a diagnosis?
Essay

What’s in a diagnosis?

Sept. 4, 2025

When Jessica Foglio’s son Ben was first diagnosed with cerebral palsy, the label didn’t feel right. Whole exome sequencing revealed a rare disorder called Salla disease. Now Jessica is building community and driving research for answers.

Peer through a window to the future of science
Annual Meeting

Peer through a window to the future of science

Sept. 3, 2025

Aaron Hoskins of the University of Wisconsin–Madison and Sandra Gabelli of Merck, co-chairs of the 2026 ASBMB annual meeting, to be held March 7–10, explain how this gathering will inspire new ideas and drive progress in molecular life sciences.

Glow-based assay sheds light on disease-causing mutations
Journal News

Glow-based assay sheds light on disease-causing mutations

Sept. 2, 2025

University of Michigan researchers create a way to screen protein structure changes caused by mutations that may lead to new rare disease therapeutics.

How signals shape DNA via gene regulation
Journal News

How signals shape DNA via gene regulation

Aug. 19, 2025

A new chromatin isolation technique reveals how signaling pathways reshape DNA-bound proteins, offering insight into potential targets for precision therapies. Read more about this recent MCP paper.

A game changer in cancer kinase target profiling
Journal News

A game changer in cancer kinase target profiling

Aug. 19, 2025

A new phosphonate-tagging method improves kinase inhibitor profiling, revealing off-target effects and paving the way for safer, more precise cancer therapies tailored to individual patients. Read more about this recent MCP paper.