Wild Potatoes Tapped for Late Blight Guard Duty
Jan Suszkiw
Distant cousins of cultivated potato may hold the key to unlocking new sources of resistance to the tuber crop's most devastating disease, late blight.
That's the hope of a team of Agricultural Research Service (ARS) scientists, who conducted laboratory trials in which they exposed the leaves of 72 different species of wild potato to spores of the late blight pathogen Phytophthora infestans—the same culprit that triggered the Irish Potato Famine of the 1840s.
Late blight remains a worldwide threat today to not only potato, but also tomato crops, inflicting an estimated $6.7 billion annually in yield losses and control costs. In susceptible varieties, the fungus-like pathogen causes dark lesions and other disease symptoms that rapidly destroy the plant's leaves, stem, fruit or tubers, noted Dennis Halterman, a plant geneticist with the ARS Vegetable Crops Research Unit in Madison, Wisconsin.
There, Halterman specializes in the genetic "arms race" that potato plants engage in with the pathogens that attack and sicken them, often forcing growers to retaliate with chemical controls like fungicide that can ratchet up production costs and concerns over environmental harm.
In collaboration with ARS scientist Shelley Jansky (retired) and ARS research associate Hari Karki, Halterman set his sights on the hard-scrabble relatives of cultivated potato growing wild in Central and South America, and Mexico, where late blight originated and co-evolved with the plant, a member of the nightshade family.
"Although most wild species make small potatoes that you would not want to eat—they could actually make you pretty sick—they exist in harsh natural environments without fertilizer, irrigation or pesticides," noted Halterman in an educational video on his efforts.