New Test to Find, Recruit Pest-Fighting
Bacteria By Jan
Suszkiw March 5, 2004
A genetic fingerprinting technique developed by
Agricultural Research Service scientists
could point the way to new strains of Pasteuria bacteria with potential
to biologically control soybean cyst nematodes.
ARS nematologist Greg Noel and colleagues developed the method
to help resolve confusion surrounding Pasteuria's taxonomic
classification and clarify its parasite-host relationship with soil-dwelling
roundworms like the soybean cyst nematode, a crop pest that costs $324 million
to $1.4 billion annually in U.S. soy losses.
Since Pasteuria can't be cultured in the lab, researchers
seeking to determine its genetic affiliation must resort to extracting DNA from
the spore-infected bodies of nematodes. It's a laborious, time-consuming affair
that's sometimes prone to DNA contamination by other microbes, according to
Noel. He is in the ARS
Soybean/Maize
Germplasm, Pathology and Genetics Research Unit at Urbana, Ill.
There, rather than using centrifuging, heat and chemicals to
obtain Pasteuria DNA, Noel resorted to "glass bead beating." The
procedure involves grinding spore-infected nematodes so that any DNA within
them is released into a sterile solution. Lab-built molecules called primers
are then added. These bind only with Pasteuria DNA--if it's present--and
ready the material for amplification by polymerase chain reaction. The DNA can
then be cloned and sequenced as Pasteuria's unique, genetic fingerprint.
According to Noel, the method is fast, easy to use, and highly
specific. Besides its taxonomic applications, it should aid scientists in
identification of Pasteuria species that attack different nematode
species. Some of these Pasteuria also complete their life cycles in
juvenile nematodes, while others do so in female nematodes.
Either way, the pests face a grisly demise. Within a month, for
example, infected soybean cyst nematode females become fragile to the point of
crumbling apart, a fate that diminished the pest's population by 87 percent in
Noel's field studies at Urbana.
Read more
about this research in the March issue of Agricultural Research
magazine.
ARS is the U.S. Department of
Agriculture's chief scientific research agency. |