||Last Updated: Apr 20, 2011 - 9:38:09 AM
Tiny, wormlike organisms called nematodes can be friend or foe to
farmers. One such foe, the soybean cyst nematode Heterodera glycines,
costs soybean farmers $1 billion annually in crop losses and chemical
controls. But now, the crop pests could become their own worst enemies,
thanks to biochemical sabotage.
Agricultural Research Service (ARS) physiologist Edward Masler is
developing this strategy at the agency's Nematology Laboratory in
Beltsville, Md. He's investigating molecules produced by the nematodes
that could be used to subvert their feeding, mating or other behaviors.
Masler's research with biogenic amines and other biochemicals is part
of a long-term effort to devise environmentally friendly alternatives
to conventional pesticides, particularly the fumigant methyl bromide,
which is restricted for all but critical uses because of its toxicity.
Masler also is targeting the root-knot nematode Meloidogyne incognita,
which infests peanut, potato, cotton and other crops. The knot-like
feeding site each nematode forms on host-crop roots restricts the
plant's access to nutrients, causing stunted growth, diminished yields
and other harm.
Since the mid-1990s, Masler has scrutinized the biochemistry of these
and other nematode crop pests for clues to disrupting such destructive
behavior. Biogenic amines, a recent focus, occur in other living
organisms. So, Masler must ensure their biological activity is
restricted solely to Heterodera and Meloidogyne nematodes.
In laboratory experiments, he exposed juvenile nematodes and unhatched
eggs to an "overdose" of one of three amines--dopamine, octopamine and
serotonin--and monitored the effects. Interestingly, 90 percent of
Heterodera eggs failed to hatch after exposure to serotonin, versus 40
percent for Meloidogyne. In juveniles of both species, serotonin
exposure decreased head-swinging--a foraging behavior--while dopamine
Ultimately, such observations could predict the amines' usefulness as
natural agents for controlling the pests under field conditions.
Proteolytic enzymes offer another potential target. Normally, they act
as cellular brakes that stop the signaling of neuropeptides called
FLPs. Masler is exploring whether removing those "enzymatic brake pads"
could cause FLPs to build to levels that will incapacitate the
nematodes, offering yet another alternative to chemically controlling
ARS is a scientific research agency of the U.S. Department of Agriculture.
ARS News Service
Agricultural Research Service, USDA
Jan Suszkiw, (301) 504-1630, [email protected]
January 7, 2009
--View this report online, plus photos and related stories, at www.ars.usda.gov/is/pr
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