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Gene Modified Potatoes Developed with Blight Resistance

Jonathan Jones

Jonathan Jones (The Sainsbury Laboratory)

24 February 2014. Researchers at The Sainsbury Laboratory in Norwich, U.K. developed and field tested a new type of potato with greater genetically modified resistance to late blight, a long-time scourge of potato growers. The team led by Sainsbury plant biologist Jonathan Jones reported its findings online last week in the journal Philosophical Transactions of the Royal Society B.

Late blight is a plant disease caused by a fungus-like organism, known as Phytophthora infestans, with a long history of destruction, attacking mainly potatoes and tomatoes. The pathogen survives from one season to the next in infected potato tubers, and in wet weather can produce millions of spores from infected plants. Late blight is believed to be the cause of the Irish potato famine of the mid-19th century, and linked to annual crop losses worldwide estimated at $5 billion.

Jones and colleagues from institutes affiliated with Sainsbury Lab developed the new type of potato from the Desiree variety, a popular potato in the U.K. with smooth red skin and yellow flesh. In their original state, Desiree potatoes have hundreds of resistance genes, but the late blight pathogen finds ways of circumventing those barriers.

The researchers found genes from Solanum potatoes, a wild relative of the Desiree in South America that enable the growing of plants to better recognize the late blight invaders and trigger their natural resistance mechanisms. Natural cross-breeding techniques, say the authors, are difficult, slow, and prone to failure. Jones notes in a Sainsbury statement that “by the time a gene is successfully introduced into a cultivated variety, the late blight pathogen may already have evolved the ability to overcome it.”

To create the new transgenic variety, Jones and colleagues isolated the genes with the desirable resistance qualities from Solanum potatoes and introduced them to the Desiree variety. The team then grew transgenic plants for three years in potato fields. Each year, they planted 192 genetically modified plants, and surrounded them with non-modified Desiree and Maris Piper potatoes, another popular variety.

The researchers did not infect the test plants, but instead let the pathogen find the plants on its own. In the last year (2012), the Norwich region experienced a wetter than normal summer, providing ideal conditions for late blight to infect the plants; the previous two years were dryer and thus less favorable to the pathogen.

The trials showed the transgenic plants were completely resistant to late blight and with all of them surviving attacks from the pathogen. Non-modified potatoes, however, were all found infected with late blight. Transgenic varieties also had higher yields of 6 to 13 kilograms of tubers per blocks of 16 plants, compared to 1.6 to 5 kilograms per 16 non-modified plants.

One consequence of the new transgenic potato variety is a reduced need to spray for late blight. The authors say that European farmers spray pesticides on their potato fields as many as 15 times a season to kill late blight, which could be sharply reduced through a strategy of genetic control instead of chemical control.

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