Potato Researchers Hear Call of the Wild : Spuds: Annual production of 299 metric tons makes it the world’s fourth most important food crop behind wheat, maize and rice.

INVERGOWIE, Scotland — Candidates for the perfect potato wait in neat rows, brown, steamy and temptingly ready for dollops of butter.

But instead of being tasted, they will be tested.

Is the flesh too waxy? Floury? Mottled with bluish-gray stains? Is the skin scaly? Will the potato resist disease and pests?

All those problems can be fixed with a little genetic engineering, Michael Wilkinson said.

He is a botanist at the publicly financed Scottish Crop Research Institute, which makes designer potatoes that won’t sprout when stored, turn an unpalatable brown when fried or need a truckload of pesticides.

The 12-year-old institute, 500 acres on the north bank of the Tay Estuary in eastern Scotland, has a gene bank of more than 1,600 varieties of 71 potato species and is one of four major research centers for potatoes. The others are in Wisconsin, Peru and Germany.

Annual production of 299 metric tons makes the potato the world’s fourth most important food crop behind wheat, maize and rice. It is grown throughout Europe, Asia, Australasia and the Americas, with the highest production in the United States, the former Soviet Union, China, Poland and India.

Conserving a diversity of plants at institutes is essential to breeding and research because commercial agriculture tends to standardize, Wilkinson said.

“In agriculture, it’s the biggest-yielding, the blandest-tasting potatoes, the squarest-shaped,” he said. “Everything that doesn’t fit into that very narrow category gets dropped out.”

In North America, more than 80% of the potato crop is Russet Burbank, the variety McDonald’s chops into French fries.

“There is the constant risk that, as the genetic base of a crop declines, so the threat of catastrophic losses following minor changes in pest or disease epidemiology increases,” Wilkinson said. “Such changes can, and have, led to economic ruin or even famine.”

The most sensational failure caused the Irish famine of the 1840s. Late blight turned potatoes to brown rot.

After World War II, the British potato crop was devastated by a soil-borne pest known as potato cyst nematode. Researchers isolated the H1 gene, which is resistant to the pest, and introduced it into commercial varieties.

“Without that single gene, it would be impossible to grow potatoes in some parts of the United Kingdom,” said George Mackay, chief of the institute’s crop genetics department.

More recently, scientists inserted a gene carrying resistance to the potato leafroll virus into the Desiree variety.

Essentially, the institute tries to keep potatoes healthy by introducing traits from wild cousins.

Gesturing toward bushy green plants in a greenhouse, Wilkinson said: “Everything has an element of wildness because the wild species are rock-hard, while the cultivated potato is a bit of a wimp, really. Disease comes along and blows them over.”

He showed off a tray of wild tubers that would never make it in the supermarket. Wilkinson likes them for their genes.

The tiny tubers range from scrawny to round. They are black, red, yellow, brown, purple, pink, speckled. Boliviennese, the oddest, resemble yogurt-covered raisins.

Crossbreeding methods used at the institute range from pollination with paintbrushes to sophisticated lab techniques that can overcome reproductive problems between species.

Wilkinson said the institute has been asked for help from around the world.

India and Chile, for example, wanted potatoes that would thrive without expensive chemicals.

Israel and other Mediterranean countries sought potatoes adapted to a warm climate. The Stirling, which dates from 1991, grows well in heat, producing round, white-skinned, white-fleshed tubers.

Wilkinson’s job takes him from desk to lab to a “mud room” where rubber boots are stored, to greenhouse, field, computer and kitchen. The aroma of baking or frying potatoes often wafts through the labs.

Right now, the institute is trying to breed a better potato for chips.

When potatoes are stored at a temperature low enough to keep them from sprouting, they accumulate sugars that cause chips to darken while being fried.

The institute’s solution: Brodick, a high-yielding potato approved for commercial growth in 1990. It fries well and resists most fungal diseases, but relatively few commercial chip makers use it because of other weaknesses.

Although the Brodick meets all the primary requirements, “its potato flavor is not as strong as some of the varieties we use,” said John Vessey of KP Foods Group, one of Britain’s largest producers of store-brand chips.

Also, he said, it is very susceptible to spraing, a disease that causes ugly brown arcs in a potato’s flesh.

In defense of the institute, Wilkinson said, “There is no cultivar on the market now that does not have at least one problem. We haven’t produced the perfect potato, but we’re constantly improving.”

Crossing a single gene from one potato species to another requires a minimum of eight years and $300,000, the botanist said, followed by 15 years of strict testing before the result can be grown commercially.

“And that’s for a potato,” he said. “The cushiest job you could have is a tree genetic engineer. One cross can take a century.”