RESISTANCE TO SOYBEAN CYST-NEMATODE AND MOLECULAR POLYMORPHISM IN VARIOUS SOURCES OF PEKING SOYBEAN

Cultivar Peking has been extensively used as a source of resistance to Race 3 and Race 5 of soybean cyst nematode, Heterodera glycines I., a nd Peking genes for resistance are present in a wide range of resistan t soybean cultivars. Peking is also used as a host differential in the soybean cyst nematode race classification system. Thirteen Peking lin es maintained in the USDA Soybean Germplasm Collection and in several breeding programs were surveyed using RFLP and RAPD markers for geneti c characterization. Based on the molecular diversity combined with rea ction to soybean cyst nematode, Peking genotypes from a common origina l source were identified. Peking lines PI 297543 (introduction from Hu ngary), and PI 438496A, PI 438496B and PI 438496C (introductions from Russia) represented unrelated germplasms. Identified molecular polymor phism can be used to validate the genetic purity of Peking lines used as host differentials for soybean cyst nematode classification system as well as utilization of an individual germplasm line in genetic-bree ding programs.