Genetic and molecular characterization of resistance to Heterodera glycines race isolates 1, 3, and 5 in Peking

Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, has caused severe damage to soybean [Glycine max (L.) Merr.] worldwide since its discovery in 1954. 'Peking' is one of the most important sources in breeding SCN resistant soybean cultivars because it is resistant to Races 1, 3, and 5. Genetic information on SCN Races 1, 3, and 5 from Peking is essential to efficiently develop resistant soybean cultivars. Resistance to Race 3 in Peking was found to be controlled by three genes, but little is known on the inheritance of resistance to Races 1 and 5, and whether alleles conditioning resistance to Races 1 and 5 belong to the same linkage group and are allelic to genes giving resistance to Race 3. To determine the genetic bases of resistance to SCN Races 1, 3, and 5, Peking was crossed to the susceptible line 'Essex' to generate F-1 hybrids. The F-2 population and F-2:3 families were advanced from the F-1 and evaluated for resistance to SCN Race isolates 1, 3, and 5. Resistance to H. glycines Race isolates 1, 3, and 5 in Peking was found to be conditioned by three genes, one dominant and two recessive (Rhg, rhg, rhg). Peking may share similar sets of resistance loci between Races 1 and 3, but not between Races 3 and 5, or between Races 1 and 5.