US biotechnologists have discovered a gene that protects potatoes against late blight, the disease that caused the Irish potato famine and a member of the family of pathogens to which all varieties of commercial potato are still susceptible.

Researchers at the University of Wisconsin-Madison found and cloned the gene after scouring the genome of a wild Mexican potato.

The researchers have since inserted the gene into an experimental crop of potato plants that have shown resistance to late blight.

Prior to the 1990s, chemical fungicides effectively held the disease at bay, but new strains of the pathogen have emerged.