An Inside Job: Using Nematodes' Own Biology Against Them

ARS scientists are looking within for environmentally friendly ways to battle nematodes. Within the nematode, that is.

"We want to find out what makes nematodes tick, and what we can do to them to make them stop ticking," says zoologist David Chitwood. He's research leader of ARS's Nematology Laboratory in Beltsville, Maryland.

These microscopic plant-parasitic worms cost U.S. farmers more than $10 billion in losses annually. Chitwood's team is probing nematodes' genes and proteins, susceptibility to toxins, and even their cholesterol levels for vulnerabilities. "We're examining basic processes like locomotion, egg hatch, and growth and development," says physiologist Edward Masler. "We're focusing on 'housekeeping molecules' that help maintain cell health and structure."

Masler and molecular biologist Andrea Skantar studied whether heat-shock proteins (HSPs) are soft spots in nematodes' armor. As a result, Skantar made the first-ever report of an important HSP in soybean cyst nematodes, the world's most important soybean pest. "HSP-90 regulates specific target proteins that control normal cell development and metabolism," she says. "It also appears to govern adaptation to environmental extremes, such as starvation and temperature stress, in many organisms."

Testing a Natural Product

Skantar and plant pathologists Lynn Carta and Susan Meyer were able to inhibit the action of HSP-90 in free-living Caenorhabditis elegans and plant-parasitic Heterodera glycines nematodes. They used geldanamycin, a compound produced by bacteria.

"We exposed nematode eggs to geldanamycin in multi-well petri dishes and discovered that it reduced hatching and hampered juveniles' ability to move about," she says. "This is important because these early life stages, which take place in soil, are vulnerable to attack with biologically based measures."

The next goal is to determine whether the geldanamycin-producing bacteria have potential as a biocontrol agent against nematodes. Although these common bacteria have stymied fungi and other plant pests, Skantar's upcoming tests will mark the first time they will be evaluated against nematodes.

Actin Gene an Enticing Lead

Masler's work led to the discovery of HSP-70, a protein that helps plant-parasitic cyst nematodes respond to stress. It also led to the first description of the actin gene in these nematodes. Actin is an abundant cellular protein active in muscular contraction, cellular movement, and cell-shape maintenance in most organisms...

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