Many soybean varieties have a naturally occurring genetic resistance to the soybean cyst nematode, a major pest affecting the crop. The number of copies of the resistance gene varies among cultivars; a new method, developed by University of Illinois researchers, is able to efficiently quantify this variation for the first time. The new method has been tested in greenhouse trials to show that the more copies of the gene, the greater the resistance to soybean cyst nematode. Breeders can use this method to develop new soybean varieties with greater and more reliable resistance.
Soybean cyst nematode is the number one soybean pest worldwide, accounting for estimated annual losses of nearly $1.3 billion in the United States. Some soybean varieties have resistance to the tiny parasitic worms through conventional breeding of naturally occurring resistance genes, but the current level of resistance is becoming less reliable.
"Our interest is in finding new sources of resistance, because the sources that people have been using are breaking down. Nematodes are becoming better at overcoming the resistance we have in current cultivars. We are also, interested in improving our understanding of how this resistance works so we can do a better job of selecting for it," says University of Illinois plant breeder, Brian Diers.