ST. PAUL, Minnesota, US -- Scientists at Agricultural Research Service (ARS), the principal intramural scientific research agency of the US Department of Agriculture (USDA), are looking to wild oat DNA as a possible combatant against crown rust, the most damaging fungal disease of oats, ARS reports in a press release. Wild oats, generally considered to be a weed, seem to hold effective resistance against Puccinia coronata, the fungus that causes crown rust, reports ARS. P. coronata reduces oat yields up to 40% and can 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.

According to Martin L. Carson, research leader at the ARS Cereal Disease Laboratory in St. Paul, Minnesota, US, P. coronata reproduces both sexually and asexually and has enough genetic flexibility to overcome resistance genes, usually in about five years. Carson's analysis also shows crown rust is increasing in virulence throughout North America.

Carson has inoculated with crown rust the seedings of Avena barbata, the slender oat. After several crosses with A.barbata, Carson 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.