Rapid Test for Global Fungal Threat
June 16, 2004
Rusts are fungal disease agents that threaten just about every
plant or crop in the world. The science of detecting rusts became a bit more
precise this year, thanks to Agricultural
Research Service scientists who developed a wheat rust species detection
kit that relies on a form of rapid DNA testing.
Geneticist Les Szabo, plant pathologist Charles Barnes and lab
technician Kim Nguyen developed the polymerase chain reaction (PCR) test to
identify the species that do the most damage to wheat: stem rust, stripe rust
and two species of leaf rust. The test identifies species by detecting specific
DNA sequences in fungal genes. The scientists work at the ARS
Cereal Disease Laboratory in St. Paul,
Extra funding from the U.S. Department of Defense--along with
many years of previous research on rust taxonomy, including creation of an
extensive database of DNA sequences--enabled Szabo to develop the test in just
Diagnostic labs will likely use the test to analyze rust samples
from around the world.
Plans for future tests include all the important rusts affecting
other major cereal grain crops, including barley, rye and oats.
Once the scientists develop kits to more accurately identify
individual rust species, they will devise additional tests to identify
subspecies and genetic lineages. This will allow labs to track the movement of
rusts worldwide and to immediately recognize types of these rust fungi that
might be new to this country.
Knowing the subspecies and lineages will also alert scientists
to which crops and varieties are at risk. This information will be useful to
farmers, and it will give scientists an early start on breeding resistant
varieties and developing new controls.
The work is expected to lead to the discovery of new species of
rust fungi, adding to the 7,000 known rust species in the world.
information about ARS rust detection research can be found in the current
issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.