Complete Potato Blight Pathogen Genome Sequenced

Posted by Matt Hopkins|9 September 2009

Scientists at the USDA Agricultural Research Service (ARS) have sequenced the complete genome of the pathogen that caused the infamous Irish potato famine and the recent loss of potato and tomato crops in the eastern United States, reports ARS News Service.

The fungus, Phytophthora infestans, causes the disease commonly known as late blight, the most destructive potato disease. It can also infect tomatoes and other members of the Solanaceae family. Once the pathogen attacks, there is little that can be don e to save the crop, which can be completely destroyed in just one week, according to ARS. Additionally, the pathogen’s ability to quickly mutate and develop resistance to current fungicides makes it difficult to control.

ARS plant pathologist Richard Jones, with the agency’s Genetic Improvement of Fruits and Vegetables Laboratory in Beltsville, Maryland, US, led a group responsible for examining and annotating the genes that produce enzymes to degrade a plant’s cell wall. Jones and colleagues found located close to each other on the genome of P. infestans several groups of enzymes which attack the surface of the plant, allowing the pathogen to break through and
begin feeding on the plant’s nutrients. The scientists believe two of these enzyme groups may be used by the pathogen at the initial stage of infection.

The researchers were also the first to identify and report a unique pattern of gene segments called introns in the pathogen’s genome that give the pathogen the ability to produce different proteins from the same gene and attack different compounds within the plant cell wall. This may further explain how the late blight pathogen is so successful in attacking plants, according to Jones.

This research is published in the scientific journal Nature.