Abstract: In this study, we analyzed genetic diversity and relationship between broccoli and its related species by SRAP molecular markers. Using 28 SRAP primer combinations, a total of 302 amplified fragments were detected and 203 were polymorphic, with polymorphism rate 67.22%, indicating high polymorphism among these germplasm. Similarity coefficient analysis showed that the variation ranged from 0.461 5 to 0.900 6, and the average genetic similarity coefficient was 0.693 6. ‘Lü di’ and ‘Ai kang qing’ had the farthest genetic relationship with genetic similarity coefficient 0.461 5. By contrast, the relationship was closest between ‘Wzvcst-09-224’ and ‘Wzvcst-09-225’, with genetic similarity coefficient 0.900 6. Cluster analysis divided 16 germplasm into two major clusters. Class I contained Brassica oleracea, and class II only had one member Chinese no heading cabbage. The result of cluster indicated that the genetic basis had more similarity between broccoli and its related species, with a closer relationship, comparing with Brassica campestris ssp. chinensis Makino. The results also showed that the same geographic or origin could make the germplasm had relatively similar genetic background and closer genetic relationship. The research could be helpful to germplasm classification and excellent genes utilization for broccoli and its relative species, to speed up the breeding process.

Key words: Broccoli, SRAP, Genetic diversity, Genetic relationship