Genetic analysis of resistance to soybean cyst nematode in PI438489B

Soybean (Glycine max L. Merr.) plant introduction PI 438489B is a unique so urce that has resistance to all known populations of soybean cyst nematode (Heterodera glycines Ichinohe, SCN). This PI line also has many desirable a gronomic characteristics, which makes it an attractive source of SCN resist ance for use in a soybean breeding program. However, characterization of SC N resistance genes in this PI line have not been fully researched. In this study, we investigated the inheritance of resistance to populations of SCN races 1, 2, 3, 5, and 14 in PI 438489B. PI 438489B was crossed to the susce ptible cultivar 'Hamilton' to generate F-1 hybrids. The random F-2 plants a nd F-3 lines were evaluated in the greenhouse fur reaction to these five po pulations of SCN races. Resistance to SCN races 1, 3, and 5 were mostly con ditioned by three genes (Rhg Rhg rhg). Resistance to race 2 was controlled by four genes (Rhg rhg rgh rgh). Three recessive genes were most likely inv olved in giving resistance to race 14. We further concluded that resistance to different populations of SCN races may share some common genes or pleio tropic effects may be involved.