COMPARISON OF RAPESEED CULTIVARS AND RESYNTHESIZED LINES BASED ON ALLOZYME AND RFLP MARKERS

It has frequently been suggested to use the resynthesis of rapeseed (B rassica napus) from B. campestris and B. oleracea to broaden its genet ic base. The objective of the present study is twofold: (1) to compare the genetic variation within resynthesized rapeseed with a world-wide collection of oilseed rape cultivars, and (2) to compare genetic dist ances estimated from RFLP markers with distances estimated from a rela tively small number of allozyme markers. We investigated 17 resynthesi zed lines and 24 rapeseed cultivars. Genetic distances were estimated either based on the electrophoresis of seven allozymes, with a total o f 38 different bands, or based on RFLP data of 51 probe/enzyme combina tions, with a total of 355 different bands. The results of allozyme an d RFLP analyses agreed reasonably well. Genetic distances, estimated f rom two independent sets of RFLP data with 25 and 26 probe/enzyme comb inations respectively, were highly correlated; hence about 50 RFLP mar kers are sufficient to characterize rapeseed material with a large gen etic diversity. The cultivars were clustered into three groups: (1) sp ring rapeseed of European and Northern American origin, (2) winter rap eseed of European and Northern American origin, and (3) rapeseed of As ian origin. Several of the resynthesized rapeseed lines were similar t o European winter rapeseed cultivars, whereas others had quite unique patterns. It is concluded, that resynthesized rapeseed is a valuable s ource for broadening the genetic variation in present breeding materia l of Brassica napus. However, different lines differ widely in their s uitability for this purpose.