September 27, 2006 — 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.
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.
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.
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
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.
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 develop 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."
Source : University of Georgia