Studies On Genetic Relationships Among Chinese Cabbage (Brassica Campestris L. Ssp.pekinensis) Germplasm

Chinese cabbage is native to China. It is rich in Chinese cabbage resources. It is meaningful to study on genetic relationships among Chinese cabbages for potentializing gene resources and serving the breeding. In this study, 89 accessions of Chinese cabbage germplasm were employed to study the genetic relationships among Chinese cabbages using morphological and AFLP makers.Variation coefficients of the 26 morphological characters distributed widely ranged from 15.9% to 77.5%. There were significant variations within the characters of floss, petiole color and clasping modality of head top. It farther verified that these three characters are very important. By the clustering analysis of morphological characters, the materials were divided into two major groups at similarity coefficient of 0.15, which indicate that the character of clasping modality of head top occupy the important position in Chinese cabbage classification. All materials were divided into three groups at similarity coefficient of 0.20.6 pairs of primer generated 286 bands, including 123 (43.01%) polymorphic bands. There is obvious difference among the numbers of total bands and polymorphic bands produced by different pairs of primer. E-ACT/M-CAC showed the best amplification effect and generated plentiful polymorphic bands that occupying 54.35% of total.Clustering analysis of AFLP showed that Chinese cabbage possesses broad variation with utmost genetic distance of 0.359. The result indicat that "Zhejiang huangyacai" was separated from most of Chinese cabbage (main Chinese cabbage) and formed into an independent group. In the group of main Chinese cabbage, the lines of Taiwan germplasms formed into an independent subgroup, and the materials in most parts of mainland formed into another subgroup. In addition, lines from Japan and Korea are also classified into this subgroup.Though there were some differences beteew the clustering analysises of morphological characters and AFLP, both of them verified that the varieties coming from main producing areas in North China compose main body of Chinese cabbage. The lines from Japan or Korea were more genetically similar to the mainland materials that verified some former viewpoints about evolution and classification of Chinese cabbage.