Abstract: The endopolyploidization is a universal phenomenon existing in the higher plant. The endopolyploidization, on which plant cells maintained a faster growth rate, is an important way of increasing copies of function genes which is necessary for plant to adapt its growing environment. The knowledge and research on the occurring and the feature of plant endopolyploidization phenomenon would be helpful for regulating efficiently differentiation of organs and accelerate the formation of valuable organs. In this paper, the Chinese cabbage and its relatives were used to determine the endopolyloidization level in tissues, organs, and leaves at different developmental stages with the technique of flow DNA analysis. The results showed that in Chinese cabbage the feature of endopolyploidization was also specific for tissues, developmental stages like in other plants reported previously. Some conducting tissues with higher lignification degree such as primary root, hypocotyls, stem and petiole demonstrated higher endo-polyploidization level than other nor-conducting tissues such as bract, cotyledon, laminae. In a given organ, the endopolyploidiza-tion level was raised in the progress of the organ development. When the organ was up to maturity its endopolypoidization level tended to be stable. The micros-graph revealed that the nuclei with different ploidies showed obvious difference in size and were scattered randomly into adjacent pellicle tissue cells of petiole of Chinese cabbage. The highest ploidy level of nuclei was 64C in leaves of Chinese cabbage, but 32C, 16C, and 16C in leaves of cabbage, mustard, and Arabidopsis thaliana, respectively, indicat-ing that the endopolyploidization level of the different plants in the same family is different.

Key words: Endopolyploidy, Chinese cabbage, Flow cytometry, C-value