Inserted gene lets potatoes resist blight

THE BALTIMORE SUN

MILWAUKEE - One gene could have changed the course of history.

Plant scientists from the University of Wisconsin-Madison have inserted a gene from a wild Mexican potato into commercial potatoes that makes them resistant to the dreaded potato blight that starved 1 million people in Ireland in the 1800s.

The breakthrough could save American potato farmers hundreds of millions of dollars a year in fungicide costs and could fight a disease that farmers worldwide have battled since the 1800s.

"So far, the plants have been resistant to everything we have thrown at them," said John Helgeson, a University of Wisconsin professor of plant pathology and research scientist with the U.S. Department of Agriculture.

The research is part of a decade-long quest by Helgeson and other University of Wisconsin scientists, who published their findings online yesterday in the Proceedings of the National Academy of Sciences.

Late potato blight is a fungal disease. Airborne spores land on potato leaves. The spores germinate on the leaves, causing dark splotches that eventually kill all of the plant above ground. The spores also find their way through the soil and infect the tubers.

"Essentially, the tubers just turn to mush in the bins," Helgeson said.

Spraying the plants as many as 25 times a season with chemicals, the typical U.S. potato farmer spends about $250 per acre to fight the disease.

Even then, new strains of the blight can emerge and render existing fungicides useless.

Several groups of researchers, both in the United States and Europe, have been trying to genetically engineer potatoes to be resistant to late blight, said David Douches, a professor of crop and soil sciences and a potato breeder at Michigan State University.

But the University of Wisconsin scientists are the first to publish research showing that insertion of a single gene can make potatoes resistant to blight, he said.

"It's very exciting," Douches said. "There have been a lot of cloned genes put in, but that doesn't work very well.

"This is going to be very beneficial to farmers."

In its long history as a staple crop, the potato has crossed the Atlantic Ocean twice.

It was first cultivated in the Andes Mountains of South America, was introduced to Europe in the 1500s by the Spanish, and was then brought to North America by other Europeans.

The Irish potato famine began in 1845 and persisted for several years.

An estimated 1 million people starved and another 1 million left the country, many coming to the United States.

A breakthrough against blight came in 1994 when University of Wisconsin researchers were studying a wild Mexican potato for blight resistance.

While that potato had no commercial value, the scientists were able to identify four different genes that they believed might make the plant blight-resistant.

Using conventional genetic engineering techniques, they inserted all four of the genes in potato plants, eventually finding one gene that offered complete resistance.

Jiming Jiang, a University of Wisconsin professor of horticulture, said the Mexican potato gene easily can be inserted into nearly any type of commercial potatoes.

The big issue, he said, is whether consumers will accept a genetically modified potato.

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