ARS Scientists Turn to a Wild Oat to Combat Crown
February 4, 2010
Agricultural Research Service (ARS)
scientists are tapping into the DNA of a wild oat, considered by some to be a
noxious weed, to see if it can help combat crown rust, the most damaging fungal
disease of oats worldwide.
Crown rust reduces oat yields up to 40 percent and shows a remarkable
ability to adapt to varieties bred to genetically resist it. ARS researchers
and colleagues have inserted individual resistance genes into oat varieties
that produce proteins believed to recognize strains of crown rust and trigger a
defense response against them. Multiline cultivars with several
resistance genes also have been developed.
Crown rust is caused by Puccinia coronata, a fungus that reproduces
both sexually and asexually and has enough genetic flexibility to overcome
resistance genes, usually in about five years, according to
L. Carson, research leader at the ARS
Disease Laboratory in St. Paul, Minn. His analysis also shows crown rust is
increasing in virulence throughout North America.
Carson has turned to a wild variety, Avena barbata, for new
genes with effective resistance. The slender oat, listed as a noxious weed in
Missouri and classified as moderately invasive in California, grows wild in
South Asia, much of Europe and around the Mediterranean region.
Carson inoculated A. barbata seedlings with crown rust. After several
crosses, he found seedlings highly resistant to a variety of crown rust
strains. In ongoing studies, he is crossing them with the domestic oat, A.
sativa, to try to develop the right blend of resistance and desirable
traits, such as high yield and drought tolerance. The goal is new plant lines
that will effectively fight off crown rust for many years.
The research, which supports the U.S.
Department of Agriculture (USDA) priority of promoting international food
security, was published in the journal Plant Disease.
more about this research in the February 2010 issue of Agricultural
ARS is USDAs principal intramural scientific research agency.