ARS Scientists Help Sequence Genome of Potato Late
Blight Pathogen By
September 9, 2009
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 has been sequenced by Agricultural Research Service (ARS)
scientists and cooperators.
Phytophthora infestans is a fungus that causes the disease
commonly known as late blight, the most destructive disease of potato. It can
also infect tomatoes and other members of the Solanaceae family. Once
the pathogen attacks, there is little a commercial grower or home gardener can
do to save the crop, which can be completely destroyed in just one week.
Additionally, the pathogen's ability to quickly mutate and develop resistance
to current fungicides makes it difficult to control.
ARS plant pathologist
Jones, with the agency's
Improvement of Fruits and Vegetables Laboratory in Beltsville, Md., led a
group responsible for examining and annotating the genes that produce enzymes
to degrade a plant's cell wall. Former postdoctoral researchers
Costanzo, now a plant pathologist at the ARS
Bumpers National Rice Research Center in Stuttgart, Ark., and
Ospina-Giraldo, now on the faculty of Lafayette College in Easton, Pa.,
contributed to this research. Ospina-Giraldo also conducted a significant
amount of this research while with Lafayette College.
Jones and colleagues found several groups of enzymes located close to
each other on the genome of P. infestans. The pathogen secretes these
enzymes to attack the surface of the plant, allowing it 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
This research is published in the scientific journal Nature.
ARS is the principal intramural scientific research agency of the
U.S. Department of