Researchers May Have Found a Way to Save Bananas

Did you know that the bananas we eat now differ from those consumed a few generations ago?

Today’s common banana is the Cavendish variety, while the Gros Michel variety, which was widely available until the 1950s, was decimated by a disease known as Fusarium wilt of banana (FWB).

The Fusarium wilt that devastated the Gros Michel bananas was caused by Fusarium oxysporum race 1, a fungal pathogen that infects bananas by invading their vascular system and disrupting water and nutrient flow.

To address this, plant biologists developed the Fusarium-resistant Cavendish variety as a replacement. However, in recent decades, a new strain of the same fungus, known as tropical race 4 (TR4), has emerged and is now threatening global banana production.

How did Fusarium oxysporum evolve to bypass resistance and infect a wide range of plants?

I am a genomicist who has dedicated the past decade to researching the genetic evolution of Fusarium oxysporum. This pathogen causes wilt and root rot in over 120 plant species, and some strains can infect humans as well.

In 2010, my lab uncovered that the F. oxysporum genome comprises two segments: a core genome common to all strains, responsible for essential functions, and an accessory genome that varies between strains and enables specialized functions, such as infecting specific plant hosts.

Each plant species has a complex immune system designed to fend off microbial attacks. To successfully infect a plant, each strain of F. oxysporum uses its accessory genome to override the plant’s specific defense mechanisms. This functional specialization enables F. oxysporum to significantly expand its range of host plants.

In our recent study, my team, along with colleagues from China and South Africa, discovered that the TR4 strain, which is lethal to Cavendish bananas, has a distinct evolutionary origin and different accessory genome sequences compared to the strain that decimated Gros Michel bananas.

When examining the interaction between the TR4 strain and its Cavendish banana host, we observed that certain activated accessory genes in the strain produce nitric oxide, a gas that is harmful to the banana.

This sudden release of toxic gas aids the infection by weakening the plant’s defense system. Meanwhile, the fungus protects itself by increasing the production of chemicals that neutralize nitric oxide.

In tracking the worldwide spread of this new variant of Fusarium oxysporum, we recognized that the primary reason for the recent resurgence of this fungal infection is the dominance of a single banana clone in the global banana industry.

Cultivating a variety of banana types could make agriculture more sustainable and lessen the disease pressure on a single crop. Farmers and researchers can manage Fusarium wilt in bananas by identifying or developing banana varieties that are tolerant or resistant to TR4.

Our research suggests that another approach to protecting Cavendish bananas could be designing effective nitric oxide scavengers to mitigate the toxic impact of the gas burst.

It may seem difficult to envision how a banana-loving consumer could contribute to the fight against the disease ravaging banana crops. However, consumers shape the market, and farmers must grow what the market demands.

You can encourage greater banana diversity in your supermarket by deliberately choosing one or more of the hundreds of other banana varieties when they become available. Additionally, purchasing local varieties of other fruits and agricultural products can help preserve plant diversity and support local farmers.

Global collaboration among scientists, farmers, industry, and consumers can help prevent future shortages of bananas and other crops.

Read the original article on: Science Alert

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