Doubling Wildrye's Chromosomes Brightens Pasture Grass' Future

It's amazing what 14 more chromosomes can do for Russian wildrye, a pasture grass introduced to the U.S. Northern Plains area from Siberia in 1927.

John Berdahl, a plant geneticist with the Agricultural Research Service, has created Russian wildrye plants that are called tetraploids because they have double the usual 14 chromosomes. The extra chromosomes result in a plant that produces larger seeds and much more robust seedlings, solving the biggest barrier to wider use of the grass.

Russian wildrye helps keep cattle well fed by providing forage with higher digestibility and protein, especially in late summer and fall when other grasses, such as crested wheatgrass, tend to become less nutritious. But farmers and ranchers still often choose those other grasses because they're easier to grow.

Berdahl, plant physiologist Al Frank and colleagues at the ARS Northern Great Plains Research Laboratory in Mandan, N.D., hope to change that by using tetraploids to breed new Russian wildrye varieties. They expect to one day see them planted extensively on marginal land in the Northern Plains and Intermountain Region.

Berdahl and colleagues created the new plants without any gene transfer or sophisticated biotechnology. Instead, they induced chromosome doubling by pressurizing flower-bearing stalks in canisters filled with nitrous oxide gas. Nitrous oxide is commonly known as "laughing gas." The nitrous oxide technique enables production of numerous tetraploid seeds and development of genetically diverse populations from which to select superior plants.

It will take about five years to release the first tetraploid Russian wildrye variety to seed growers. Then it will take a few more years for seed growers to produce enough pedigreed seed for sale to farmers, bringing the new variety to market around 2010.

ARS is the U.S. Department of Agriculture's chief scientific research agency.