INHERITANCE OF RESISTANCE AND GENETIC-RELATIONSHIPS AMONG SOYBEAN PLANT INTRODUCTIONS TO RACES OF SOYBEAN CYST NEMATODE

The objectives of this study were to determine if genes for resistance to soybean cyst nematode (SCN) in soybean PI 437654 were identical or different from the genes in Peking, and PI 90763. The F2 plants and F3 families were studied from crosses between PI 437654, Peking, and PI 90763. The cross PI 437654 x susceptible Essex was included to determine inheritance of resistance to SCN. For Race 3, PI 437654 was found to have genes in common with Peking and PI 90763. The segregation in PI 437654 X Essex indicated the presence of one dominant and two recessive genes. For Race 5, PI 437654 indicated the presence of similar genes as those in PI 90763 and Peking whereas, PI 437654 X Essex indicated the action of the segregation ratios of two dominant and two recessive genes. For Race 14, the data from the cross PI 437654 X PI 90763 indicated monogenic inheritance with resistance being dominant; whereas PI 437654 X Peking showed a recessive gene controlling resistance. The segregation in PI 437654(R) X Essex(S) suggested one dominant and two recessive genes for Race 14 reaction.