Bananas in trouble: a fungal pandemic
Next up, it’s the world’s favourite fruit, bananas! But partly as a result of their popularity, bananas are at risk from a plant pandemic, which could see supplies dry up. Chris Smith spoke to Fernando Garcia-Bastidas, a banana scientist from KeyGene...
Fernando - It's indeed an ongoing banana pandemic that has the potential to wipe out banana plantation. It is rapidly spreading and this situation really threatens global banana production. Mostly because all the bananas in the market are identical, meaning that all of them are susceptible to this disease. This already happened in the past and with another race of this disease and a different cultivar. So we know that it's something serious.
Chris - What is the cause of the banana plants dying?
Fernando - Yes, the pathogen is a fungus, which is called fusarium and causes the disease known as Panama disease. It's caused by a solver fungus. So that means that it lives in the soil. This fungus interacts with the plant and essentially kills banana plants. This fungus also produces lots of spores that are easy to spread. So for example, if you go to a farm in the Philippines, for example, and you use the same shoes in a farm in Colombia, you are bringing the pathogen with you.
Chris - Goodness. And how far afield is the pandemic now, where's affected?
Fernando - For more than 30 years, this pandemic was restricted to Southeast Asia. So it was present only in the Philippines in Malaysia, Taiwan, Indonesia, but then in 2012, we found it for the first time outside of this area, in Jordan, and lately, it was described by the other scientists also in Oman, in Mozambique, we discovered it in Pakistan, in Lebanon, then in Israel, Turkey, Myanmar, and like that, it's been spreading very fast. Currently there are more than 20 countries with the pathogen. And the most striking thing is that it's present almost in every continent. In 2019, for example, I discovered for the first time in Colombia and that's really bad news because if you go to the supermarket for example, and you check the stickers of the bananas, most bananas come from Latin America. And this, this is, has the potential to destroy all banana plantations. Recently, it was also discovered in Peru.
Chris - You mentioned that the reason bananas are susceptible to this is because they are all genetically identical because they're all effectively clones, a bit like the Irish potato famine was because potatoes are all genetically identical. Along comes something that it can attack one plant, so it can attack every plant because they're identical. How are you trying to tackle the problems?
Fernando - There are only a few options to control this disease because so far not even chemical controls can kill this pathogen because it's in the soil and in the soil is very difficult to tackle. So the most logical way to tackle this problem is to generate a new banana. So essentially there are two ways to generate a new banana either by traditional breeding, which is using the pollen of one plant and pollinate other banana plants or transgenics, which is taking the DNA of another plant, helpfully another banana, and introduce it into, uh, an edible banana
Chris - Bananas only very infrequently have plant flowers, don't they? So they're very, very hard to grow via the pollen route. So the transgenic sort of moving genes seems to be more promising. Is that what you're doing?
Fernando - No, actually I'm doing traditional breeding. I'm using the pollen because you know, it's more complex with transgenics in terms of acceptance of the, of the customers. So I'm using traditional breeding and of course the edible bananas, the bananas that we have in the supermarkets are very difficult to improve. But what we are doing is to go to the ancestors of the bananas and those ones are easy to cross, to mix and to generate new bananas.
Chris - And what do they taste like? Are they any good?
Fernando - Yeah, they taste fantastic. There are even different kinds of flavors. We have bananas that tastes like apples, for example, or sweet there or, or more, uh, less sweet. So the diversity of bananas is huge. If you go to the center of origin of the bananas in Southeast Asia, they are more than a thousand different cultivars, but they don't look as pretty as the Cavendish, the one that we have in the supermarket. So what I'm doing now is trying to combine different types of bananas. So far, we identified the ones that are resistant to that specific disease, but unfortunately they are not ready because they are not pretty. They are not big enough, the skin is too thin, they don't ripen at the right moment. So we need to continue with breeding. And that takes a lot of time.