QTL Mapping of Vernalization Requirement in Brassica rapa

An F2 population,derived from a cross between the vernalization independent genotype‘Rc Br’and the vernalization dependent genotype‘08A061’,was developed to construct a linkage map with 165 SSR and In Del markers. QTL analysis was performed by two phenotypic evaluation( days to 5 cm elongate stalk and flowering time) based on the difference in F2: 3families under vernalization and no vernalization. The results showed that the vernalization requirement was recessive in Brassica rapa. Seven QTLs that controlled vernalization requirement were detected on A02 and A06 linkage groups,which explained phenotypic variation ranging from 0. 08% to 22. 52%. Two QTLs( VR-DE01,VR-FT01) were detected on the top of A02,which explained 22. 52% and 14. 54% of the phenotypic variation,respectively,and closely linked with Br FLC2 gene. Two QTLs( VR-DE03,VR-DE04) were detected on A06 with 13. 30% and 13. 64% of phenotypic variation. These detected QTLs will provide useful information on understanding the genetic basis between vernalization requirement and bolting,and that will be useful for marker-assisted selection( MAS) in a breeding program for bolting resistant cultivars.