By Stephanie Schupska
University of
Georgia
University of Georgia professor Richard Hussey has spent 20 years
studying a
worm-shaped parasite too small to see without a microscope. His
discovery is vastly
bigger.
Hussey and his research team have found a way to halt the damage
caused by one
of the world’s most destructive groups of plant pathogens.
Root-knot nematodes are the most economically important group of
plant-parasitic
nematodes worldwide, said Hussey, a distinguished research
professor in plant
pathology at the UGA College of Agricultural and Environmental
Sciences.
They attack nearly every food and fiber crop grown, about 2,000
plant species in all.
The nematode invades plant roots, and by feeding on the roots’
cells, they cause the
roots to grow large galls, or knots, damaging the crop and
reducing its yields.
Working with assistant research scientist Guozhong Huang and
research technician
Rex Allen, Hussey discovered how to make plants resistant to
root-knot nematode
infection.
Eric Davis at North Carolina State University and Thomas Baum at
Iowa State
University also collaborated on the research.
The discovery “has the potential to revolutionize root-knot
resistance in all crops,”
Hussey said.
The most cost-effective and sustainable management tactic for
preventing root-
knot nematode damage and reducing growers’ losses, he said, is to
develop
resistant plants that prevent the nematode from feeding on the
roots. Because root-
knot nematode resistance doesn’t come naturally in most crops,
Hussey’s group
bioengineered their own.
The results of the study were published Sept. 26 in the journal,
Proceedings of the
National Academy of Sciences.
Four common root-knot nematode species account for 95 percent of
all infestations
in agricultural land. By discovering a root-knot nematode
parasitism gene that’s
essential for the nematode to infect crops, the scientists have
developed a
resistance gene effective against all four species.
Using a technique called RNA interference, the researchers have
effectively turned
the nematode’s biology against itself. They genetically modified
Arabidopsis, a
model plant, to produce double-stranded RNA to knock out the
specific parasitism
gene in the nematode when it feeds on the plant roots.
This knocked out the parasitism gene in the nematode and
disrupted its ability to
infect plants.
“No natural root-knot resistance gene has this effective range of
root-knot
nematode resistance,” Hussey said.
The researchers’ efforts have been directed primarily at
understanding the
molecular tools the nematode uses to infect plants. This is a
prerequisite for
bioengineering durable resistance to these nematodes in crop
plants.
Through this research, they’ve discovered the parasitism genes
that make a
nematode a plant parasite so it can attack and feed on crops,
Huang said.
“Our results of in-plant RNA interference silencing of a
parasitism gene in root-knot
nematodes provides a way to development crops with broad
resistance to this
destructive pathogen,” Hussey said. “Equally important, our
approach makes
available a strategy for developing root-knot-nematode-resistant
crops for which
natural resistance genes do not exist.”
Funding for the project came from the U.S. Department of
Agriculture’s Cooperative
State Research, Education and Extension Service National Research
Initiative and the
UGA CAES.
