The Fight Against Blight

The Fight Against Blight

By Laura Secorun Palet



Because if we’re going to double the world’s food production by 2050, then we need to start taking plant diseases seriously.

By Laura Secorun Palet

Beginning in 1845, a potato blight epidemic in Ireland caused mass starvation and approximately 1 million deaths. Now, more than a century and a half later, researchers in Oxford’s Sainsbury Laboratory have discovered new clues about how the devastating pathogen behind the Great Famine operates — insights that could bring science one controversial step closer to developing blight-resistant crops.

The Oxford study, published in Science, examines the biochemical differences between two related blight strains affecting potatoes and the four o’clock flower. The findings may not be particularly glamorous, but understanding how such pathogens adapt to new hosts and spread between plant species is crucial in the fight against a disease so harmful that the U.S. once researched it as potential agent for biological weapons.

In fact, the same pathogen, Phytophthora infestans, that caused the Great Famine still affects tomatoes and potatoes today, all over the world, costing an estimated $7 billion a year. That’s enough money to feed the entire world for 2.7 days.

BW image of scienstist looking through a microscope

A field laboratory in Worcestershire, England, in May 1942

Source Corbis

While farmers in the West can better afford the expensive pesticides to fight it, the risk of blight is a much more dangerous gamble for farmers in the developing world. And with the world’s food production needs expected to double by 2050, scientists recognize they must root out vegetable disease.

Blight-resistant vegetables could be great for farmers, as well as for the environment.

Scientists have been trying to find a solution for decades, but the first step — understanding the disease — is also the hardest. “You have to know your enemy,” says Professor Sophien Kamoun, head of the Sainsbury Laboratory.

In the case of potato blight, Kamoun and others have discovered how the Phytophthora infestans pathogen and its sister species secrete substances that work to disable its target plant’s defense system.

“What’s exciting about our latest findings is that we now know, with unprecedented detailed, how the pathogen evolved,” he explains. ”This information about how the blight shuts down its host’s defenses can be the key to designing vegetables that can detect the pathogen and fight it on their own. This could help rid the world of blight once and for all.”

The main challenge is that genetic resistance is often short-lived because the pathogen, like a flu virus, can mutate into a new strain and overcome it. This is why understanding how the pathogen evolves is so fundamental.

Potato looking spoiled photographed on black

Potato Late Blight (Phytophthora infestans) damage in a Potato tuber section

Source Corbis

“If we could breed plants with proteases that can detect the blight effectors, we could prevent them from ‘sneaking in’ and making more resistant plants,” explains Dr. Renier van der Hoorn, co-author of the study.

Blight-resistant vegetables could be great for farmers, as well as for the environment. Potatoes are sprayed against blight up to 12 times a season in some countries, and a genetically modified variety could bring this number down to two.

The same pathogen that caused the Great Famine still affects tomatoes and potatoes today, costing an estimated $7 billion a year.

A new generation of smarter crops could also increase food security worldwide, which is a growing concern. “I don’t think people realize how much of a threat pathogens pose to food production. We are lucky to have an inexpensive and ample food supply, but a devastating disease can always be just around the corner,” says Professor Howard Judelson, lead researcher of blight disease at the University of California, Riverside.

Indeed, blight can cause havoc worldwide, putting farmers out of business, increasing food prices and resulting in famine.

With the world’s population set to grow by 2 billion in the next 40 years, disease control is more urgent than ever.

“What we need is a new green revolution,” says Kamoun, who also oversees similar studies on pathogens affecting rice and wheat. “The risks are high, but I am optimistic about the possibilities of genetic resistance.”

Not everyone is as excited, however, by the prospect of genetically designed supercrops. Many consumers and anti-GM (genetically modified foods) lobbyists remain skeptical.

“There is just no market interest, especially in Europe, where people are really concerned about the potential ecological and social consequences of GM. So instead of pushing solutions that consumers don’t want, the industry should be looking at other alternatives,” says Mute Schimpf, food campaigner for Friends of the Earth, a network of environmental organizations around the world.

tomatoes that look bruised and spoiled photographed on black

Late blight (Phytophthora infestans) damage to unripened glasshouse tomatoes

Source Corbis

Researchers, however, insist that these fears are exaggerated. “GM is not good or bad. It’s a technology like any other,” says Kamoun.

And while there’s no guarantee that the blight-resistant potatoes of the future will taste any better, as our understanding of plant disease expands, they will likely not be the only vegetable on your table to come equipped with a little additional protection.