MU Soybean Breeder Studies Rust-resistance Options from USDA List as Spring Planting Season Approaches By Duane Dailey

COLUMBIA, Mo. - David Sleper pores over a seed catalog, much as home gardeners ponder the possibilities in their wish books before spring planting season.

Sleper, University of Missouri soybean breeder, is studying a list of 775 soybean varieties released this week by the U.S. Department of Agriculture. Each bean variety contains resistance to Asian Soybean Rust.

USDA scientists grew and tested the soybeans in biologically secure greenhouses at Fort Detrick, Md. That is where the U.S. military maintains biological defense research programs.

Glen Hartman, plant pathologist with USDA Agricultural Research Service at the University of Illinois, exposed soybean varieties to the fungal spores in secure greenhouses on the military base. He will evaluate germ plasm available to plant breeders from the U.S. seed bank.

Varieties on the USDA list range from maturity group 000 suitable for Canadian growing seasons to maturity group 10 for the tropics.

Sleper will select resistant varieties to crossbreed with commercial soybeans available to Missouri farmers. Sleper, a part of the MU bean team at the National Center for Soybean Biotechnology, has already developed varieties resistant to the Soybean Cyst Nematode, a pest from China.

His task will be to breed varieties adapted to Missouri that will not die when exposed to the virulent soybean rust fungus. Asian Soybean Rust was confirmed on plants collected in the Missouri Bootheel at the end of the 2004 growing season. Scientists from MU Delta Center, Portageville, Mo., found the rust just days ahead of the first killing frost last fall.

A month earlier, the first soybean rust in the United States was found in Louisiana. Plant scientists suspect hurricane winds carried rust spores from South America to this country.

Soybean rust caused 80 to 100 percent crop loss in unsprayed fields in some areas of Brazil, Timely fungicide applications reduce rust damage. However, spraying adds costs for farmers. Resistant varieties will reduce the need for spraying.

Illustration by: Joel Floyd USDA, APHIS, PPQ http://www.aphis.usda.gov/ppq/ep/soybean_rust/illustration.html

Soybean varieties with rust resistance on the USDA list are available to crop breeders at agricultural experiment stations across the country.

Sleper has one variety on the list growing in greenhouses on the MU campus. Crossbreeding is under way.

Henry Nguyen, director of the MU soybean biotech center, brought a gift of seed back from his home country of Vietnam. Scientists there gave him samples to use in research on the soybean genome.

"At that time, we didn’t know soybean rust would be found in the United States so soon," Nguyen said.

Plant breeders in Vietnam have added rust resistance to their soybean varieties. The fungus has been a problem for decades in Southeast Asia.

Nguyen points out that the original genetics for all U.S. soybean varieties came from China and neighboring countries. "Now we can look for genes with rust resistance in soybeans from that region."

"First, we must determine if the rust found in the United States is of the same race that these (Vietnamese) soybeans resist," Nguyen said.

MU researchers will send new varieties to Vietnam to be field tested in rust-infested plots.

"We need field tests to determine if we have successfully transferred rust resistance genes,” Sleper said.

Cooperating Vietnamese scientists planted 100 of Missouri’s best soybean breeding lines in their fields in February. MU scientists will visit the research plots in May to evaluate survival rates.

Sleper sent 50 soybean varieties from his breeding program. Grover Shannon, MU soybean breeder at the Delta Center, sent 50 varieties from the southern breeding program.

Some MU varieties may already carry rust resistance.
Source: David Sleper 573-882-7320

Duane Dailey, Senior Writer Extension & Ag Information, University of Missouri (573) 882-9181