29 January 1999

GMspuds appeal in North America

GM POTATOES are cutting insecticide use and taking an increasing area of the US crop. Virus resistant varieties will be grown commercially this spring, and improved quality traits are in the pipeline.

"Potatoes with leaves expressing Bt insect resistance have given growers season long protection from Colorado beetle," says Monsantos Brad Krohn. "That has decreased their pesticide usage by 42%."

Uptake of the modified potatoes, marketed under the NewLeaf brand, has been rapid. Last season 19,400ha (48,000 acres) were grown, including 30% of the Russet Burbank crop. This year 36,400ha (90,000 acres) will be grown in the US and Canada, he claims.

Combining the Bt resistance with potato leaf roll virus tolerance will allow an 80% reduction of insecticide use, he adds. Such potatoes will be marketed this spring, as will potatoes with potato virus Y resistance combined with the Bt resistance.

"This could substantially cut the cost of seed production," he adds.

Development of anti-blackspot lines of Russet Burbank is also advanced. "For three years in a row we have shown a commercial decrease in bruising. The potatoes dont bruise and are still white even 48 hours later." Quality traits such as this and high dry matter lines will be combined with virus, insect or disease resistance traits to produce so called NewLeaf Ultra potatoes, with a combination of modified characters.

Growers have to grow 20% non-Bt potatoes as a legislative precaution against insects overcoming the resistance. "But so far we havent seen any resistance in beetles on the Bt plants, and the beetles flock to the non-Bt crops," notes Dr Krohn.

Resistance to single gene modifications by the blight pathogen is more likely, so the company is developing lines with multi-gene resistance mechanisms. "We would not put out a single gene resistance line as it would not be good for anyone in the industry if it failed," he concludes. &#42


&#8226 36,400ha beetle resistant in 1999.

&#8226 Virus resistance available 1999.

&#8226 Blight resistance under test.

&#8226 Quality improvements soon.