I like bananas — there, I have said it. They are one of my go-to fruits. But did you know they are in danger of being wiped out and no longer available?
In this video - How CRISPR Could Save Bananas from Extinction | The Cavendish Crisis Explained - I look at why bananas are in trouble and how genetic engineering may come to the rescue.
About 99% of bananas we eat come from a single strain known as the Cavendish. Unfortunately, this strain faces a threat that could wipe it out.
The Cavendish Banana: A Monoculture at Risk
As popular as it is, the Cavendish banana has a significant vulnerability. It's sterile, meaning it can’t reproduce through seeds like many other plants. Instead, it’s propagated through cuttings. While this has allowed us to produce vast quantities of genetically identical bananas, it also means that if a disease affects one plant, it can quickly spread to all Cavendish bananas worldwide.
Fusarium wilt tropical race 4, or TR4, is a fungus threatening to wipe out the Cavendish banana. TR4 attacks the plant's roots, eventually killing it. Because the Cavendish is sterile, traditional breeding methods can’t be used to introduce resistance to this fungus, making the banana especially vulnerable.
Worryingly, this isn’t the first time a banana strain has faced extinction due to a fungal disease. Before the Cavendish, the Gros Michel banana was the world's favourite. However, attacked by a different strain of Fusarium wilt, leading to its near-total disappearance from the market. The Cavendish was introduced as a replacement, but now it’s facing a similar fate.
How Can We Save the Cavendish Banana?
Traditional breeding can't be used as the Cavendish is sterile. Hence, scientists are using genetic engineering to save the banana. One of the most promising approaches involves tweaking the banana’s genome to make it resistant to TR4.
One explored method is inserting a resistance gene from wild bananas into the Cavendish. The wild bananas have naturally evolved to resist the fungus, and by transferring their genes, we could give the Cavendish the same level of resistance.
However, an even more interesting approach would be to use CRISPR to make precise changes to the banana’s DNA. In the case of the Cavendish banana, CRISPR could be used to activate a gene that has been silenced but could provide resistance to TR4. Additionally, CRISPR could deactivate genes that make the Cavendish susceptible to the fungus.
Why CRISPR is a Game-Changer
The advantage of using CRISPR is that it doesn’t involve inserting foreign DNA into the banana. This means the resulting banana wouldn’t be considered transgenic, which could ease regulatory hurdles and public concerns about genetically modified organisms (GMOs).
