GENETIC DIVERSITY OF OILSEED BRASSICA-NAPUS GERM PLASM BASED ON RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS

Oilseed rape (Brassica napus) is an important oilseed crop worldwide. Cultivars have been developed for many growing regions, however little is known about genetic diversity in B. napus germ plasm. The purpose of the research presented here was to study the genetic diversity and relationships of B. napus accessions using restriction fragment length polymorphisms (RFLPs). Eighty three B. napus accessions were screened using 43 genomic DNA clones which revealed 161 polymorphic fragments. Each accession was uniquely identified by the markers with the except ion of the near-isogenic cvs 'Triton' and 'Tower'. The RFLP data were analyzed by cluster analysis of similarity coefficients and by princip al component analysis. Overall, there were three major groups of culti vars. The first group included only spring accessions, the second most ly winter accessions and the third, rutabagas and oilseed rape accessi ons from China and Japan. These results indicate that within B. napus, winter and spring cultivars represent genetically distinct groups. Th e grouping of accessions by cluster analysis was generally consistent with known pedigrees. This consistency included the grouping of lines derived both by backcrossing or self-pollination with their parents.