Scientists Adapt DNA Test to Sugarbeet
By Ben Hardin
August 31, 1999
Sugarbeet growers may soon get a new
tool for identifying fungi poised to damage their crop. With the same basic
technology used in diagnosing human disease, Agricultural Research Service scientists
developed a way to quickly identify any of six major fungi types that attack
U.S. sugarbeets. Each disease can cause multimillion-dollar losses.
Developed at ARS' Red River Valley
Agricultural Research Center, Fargo, N.D., the diagnostic process can be
completed within 8 hours. Researchers designed DNA probes that detect unique
DNA segments for each fungal type.
Using polymerase chain reaction (PCR), the scientists reproduce millions of
copies of unique segments occurring in a plant tissue sample harboring fungi.
From the amplified DNA, they can quickly distinguish pathogens by a DNA
fingerprint generated when DNA is cut into pieces with an enzyme.
With PCR, scientists dont have to isolate fungi from diseased roots or
leaves and spend days culturing them before theyre identified. Rapid
identification of offending microbes by their DNA would tip off growers to the
need for applying the most appropriate control measures before diseases
seriously curtail yields.
Further research aims at narrowing the fungi's identification by species as
well as genus. The scientists have already developed probes to distinguish
Aphanomyces cochlioides, which causes black root disease of
sugarbeet, from A. euteiches, which causes root rot in peas and
other legumes. Other sugarbeet fungi include Pythium ultimum,
Cercospora beticola, Phoma betae, Fusarium
oxysporum and Rhizoctonia solani.
Another goal is to use the technology to analyze fungi in field soils as
well as plant samples. By knowing soil infestation levels, farmers could better
decide when and where to rotate crops.
ARS is USDA's chief research agency.
Scientific contact: John J. Weiland,
Sugarbeet and Potato
Research, ARS Red River Valley Agricultural Research Center, Fargo, N.D.,
phone (701) 239-1373; fax (701) 239-1349,