Abstract：High polymorphism genome representative library is the key for an efficient molecular marker technique based on microarray or sequencing. A genome representative libray with relatively high polymorphism ratio was developed by differential substractive chain (DSC). Nine accessions belonging to different Brassica campestris cultivar groups were used, eight of the nine accessions were mixed as tester DNA, while one accession mizuna (B.campestris ssp. nipposinica) was used as driver. The two DNA samples were both digested by EcoRⅠ/MseⅠbefore ligated to different adapters. Three rounds DSC were performed before the product was ligated to the GatewayTM vector pDONR201. Southern Dot blots were proformed by tester or driver probes using two randomly selected batches of clones (20 and 95 clones), respectively. The results showed 9 clones in the first batch and 58 clones in the second batch were polymorphic, with polymorphism rate of 45% and 61% respectively, indicating that the constructed library has a significantly higher polymorphism rate than those in previous reported research (15%～17%) by diversity array technology (DArT).
