Use of Genetic Diversity for Improving Resistance to Soybean Cyst Nematode in Soybean
Brian Diers, University of Illinois at Urbana-Champaign
Abstract: Soybean cyst nematode (SCN), Heterodera glycines (HG) Ichinohe, is estimated to be the pathogen that causes the greatest economic loss to soybean [Glycine max (L.) Merrill] in the USA. Over 100 sources of SCN resistance have been identified through screening the USDA Soybean Germplasm collection and resistance has been bred into high yielding varieties. Although many sources of resistance have been identified, the resistance source for over 95% of the soybean varieties in the northern USA is PI88788. The genetic basis of SCN resistance is being studied and the major SCN resistance locus rhg1 was mapped in PI 88788 and many other resistance sources. This locus was cloned showing that it is complex with both copy number and sequence variation present among accessions from the collection. This information has provided tools to identify SCN resistant accessions in the USDA Soybean Germplasm Collection that do not have Rhg1 and to identify additional diversity at this locus. To further enhance the resistance level of soybean varieties available to farmers, there have been efforts to map new SCN resistance genes from accessions in the collection. We mapped two resistance genes from the wild soybean (Glycine soja Sieb. & Zucc.) accession PI 468916. These two genes were backcrossed into high yielding soybean backgrounds and have been pyramided with Rhg1 and other resistance genes. We have found that pyramiding genes from different sources has successfully improved overall resistance. We recently released a high yielding variety with improved resistance through pyramiding genes from G. soja and Rhg1, which is one of the few examples of a soybean variety release with traits introgressed from G. soja.
Bio: Brian Diers is a Professor in the Crop Sciences Department at the University of Illinois. He earned his B.S. degree from the University of Minnesota and his M.S. and Ph.D. degrees from Iowa State University. Dr. Diers leads a soybean breeding and genetics program and teaches introductory genetics. His research focuses on utilizing exotic germplasm to improve the disease and pest resistance and yield potential of soybean. A major contribution of his program has been the mapping and utilization of genes that provide resistance to soybean cyst nematode, soybean aphid, and sudden death syndrome of soybean. In addition, he is mapping genes from exotic germplasm that can increase seed yield.
