Genetic diversity of soybean and the establishment of a core collection focused on resistance to soybean cyst nematode

Soybean cyst nematode (SCN; Heterodera glycines) is one of the most important pests affecting soybean production. The best method of control of SCN is through the development of resistant cultivars. However, limited progress has been made in soybean breeding in China because most modern cultivars have no resistance to SCN. The distribution and phenotype of 432 immune or highly resistant Chinese accessions were surveyed and a primary core collection was selected as a representative sample for further analyses. Using evenly distributed simple sequence repeat markers, five selection methods were applied to the primary core collection and the optimal method was chosen to establish a core collection, which consisted of 28 accessions. These encompassed 70.8% of the allelic variation present in the overall resistant collection. The 28 accessions differed from the reference resistant accessions at the genomic level, indicating that Chinese resistant accessions are distinct from known resistant accessions. This applied core collection provides a rational framework for undertaking diversity surveys, using genetic variation for the investigation of complex traits and for the discovery of novel traits.