Stacking Resistance Alleles from Three Sources to Increase Resistance to Soybean Cyst Nematode (SCN)

摘要

Soybean cyst nematode (SCN), Heterodera glycines (HG) Ichinohe, is the pathogen that causes the greatest yield losses to soybean [Glycine max (L.) Merrill] with estimated losses in the United States of more than a billion dollars a year. The best method to manage SCN is through the use of resistant varieties. Genetic resistance to SCN is controlled by several genes known as quantitative trait loci (QTL). More than 118 soybean accessions have been identified as possible sources of resistance to SCN; however, only seven resistant sources are commonly used by breeders. The most widely used resistance source is PI88788. With the ability of some field SCN populations to overcome these resistance sources, it is important to continue to evaluate novel resistance sources. A genetic region from PI567516C on chromosome (chr) 10 (formerly linkage group (LG) O) has been identified and confirmed to confer resistance to many SCN isolates. Additionally, two resistance QTL from wild soybean {Glycine soja Siebold &Zucc.) accession PI468916 have been mapped to regions on chr 15 (LG E) and 18 (LG G). The two QTL have been confirmed and designated as cqSCN-006 and cqSCN-007, respectively. In this study, a population segregating for resistance from PI567516C, PI468916, and PI88788 was evaluated with two nematode isolates, HG type 1.2.3.5.6.7 and HG type 1.2.3.4.5.6.7. In these stacks of resistance genes, the SCN resistance alleles from each source significantly increased SCN resistance compared to the alternative alleles. Lines homozygous for the four resistance alleles had a lower SCN female index (Fl) than those homozygous for the susceptible alleles. These results indicate that combining multiple sources of resistance can be an effective means to increase SCN resistance.