Scientists Trace Source Of Famed Irish Potato Famine

We now know what caused the Irish potato famine. Scientists have pinpointed the pathogen by using plant samples collected in the mid-19th century. Weekends on All Things Considered host Jacki Lyden talks about it with the study's co-author, Sophien Kamoun of the Sainsbury Lab in the United Kingdom.

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JACKI LYDEN, HOST:

It happened more than 150 years ago, but the devastation it wrought still reverberates today. The Irish potato blight reduced fields to rotten mush, causing mass starvation and driving more than a million Irish to flee, seeking a better life. And as it turns out, that enormous famine was caused by one tiny pest, a pathogen.

A team of researchers based here in the U.S. and in Europe was only recently able to identify it. Sophien Kamoun, senior scientist at the Sainsbury Lab in the U.K., was a co-author of the study.

SOPHIEN KAMOUN: We went to museum specimens and took diseased potato leaves that have been stored all the time in these museums. And we extracted DNA. We extracted genetic material from these leaves. And we're able - using the latest technology - to sequence the genome of the potato blight.

LYDEN: Wow. So I understand that some of these old potato leaves were actually stored at the Royal Gardens at Kew in London.

KAMOUN: Absolutely. We got samples from there. Some of them date back to Ireland from 1845, just the start of the epidemic. Yes, it was great to really access this material. It's hidden treasures, really, in these museums. Amazing.

LYDEN: And what did you call this pathogen? Describe it, would you?

KAMOUN: Yes. What we found was really interesting. What we found is a new strain of the potato blight pathogen. We called it HERB-1. And what was interesting about HERB-1 is HERB-1 is different from all the modern strains we looked at. So what we think has happened is HERB-1 is gone. It's extinct. HERB-1 was quite dominant in the 19th century. It's the only strain we could detect over a period of 50 years.

But what happened is in the 20th century, it was replaced by another strain known as US-1. And US-1 dominated most of the 20th century before being replaced, it says, by other strains.

LYDEN: What does that teach you, Sophien Kamoun, as a scientist about the way that pathogens evolve?

KAMOUN: It's a very interesting lesson. It teaches us that these pathogens are very dynamic. They're changing all the time. They're adapting to the breeding we do to try to bring in resistant potatoes and - in all of these pathogens and its ability to change and evolve and really keep up with us people and scientists.

LYDEN: The potato is still a very important food to feed the world's hungry. Should we be concerned about new potato blights?

KAMOUN: Potato is still a very important crop in the world. It's the third most important food crop. And potato blight is the most important disease of potato. And so it is a very important disease, and we still need to manage this pathogen.

LYDEN: So what is in the future using this same DNA sequencing?

KAMOUN: There's hidden treasures in these museums and (unintelligible). It's amazing that now we can go back and exploit this material that's stored in these museums and look not just at the shape of the leaves or the shape of the flowers or identify the species that are stored there, but also study the genetic makeup of all these samples that are there. I like to say that going back to the past is important for preparing to the future.

LYDEN: That's Sophien Kamoun, senior scientist at the Sainsbury Lab in Norwich in the United Kingdom. He's co-author of the study detecting the source of the Irish potato famine. Thanks so much for being with us.

KAMOUN: Thank you, Jacki.

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