Cytology Observation And Inducement Of Hexaploid Of Narcissus Tazetta Var. Chinesis Roem.

Chinese narcissus (Narcissus tazetta var. chinensis Roem.) has been a favorite ornamental plant in China for several hundreds years. Since this plant blooms and has no seeds, it only reproduced by vegetative propagation, which makes difficulty to produce new types of Chinese narcissus largely. In this work, we studied the karyotype of Chinese narcissus and observed its chromosome behavior of microspore mother cells during meiosis. Anther culture technique of Chinese narcissus was also developed in order to induce callus for cell and gene engineering. Finally, we induced hexaploid of Narcissus tazetta var. chinensis Roem. by using colchicine, and investigated the mechanism of chromosome changes of induced plantlets. The results were as following:There were some different reports for the karyotype of Chinese narcissus (Narcissus tazetta var. chinensis Roem.). Based on the former study, our result of karyotype analysis for Chinese narcissus supported the viewpoint that Chinese narcissus belongs to triploid plant, and its karyotype leans to a heterogeneous triploid. During the meiosis of microspore mother cell (MMC), the most of them displayed abnormal chromosomes: some chromosomes were out of the spindle of the cell at metaphase, some chromosome bridges were formed in some MMC at anaphase and many microspores displayed the micronucleus at the telophase. The abnormality of chromosomes during meiosis will affect microspore development and most of them abort during it late development. The phenomenon of abnormal chromosome also supports the viewpoint that Chinese narcissus is a heterogeneous triploid plant.Anthers of Chinese narcissus (Narcissus tazetta var. chinensis Roem.) were used as explants for callus induction and plant regeneration. About 70-80% anthers produced callus and 30% of the callus differentiated bulbs. About 70-80% bulbs have taken roots, making a good experiment system of tissue culture of Chinese narcissus for further cellular and gene engineering.The 700 callus were treated by 0.5% colchicine for 5-6 days and then transformed to a MS medium containing 3mg/L 6-BA to induce differentiation. 90 bulbs were obtained and 55 bulbs among them were checked chromosome number from their root tips for three times. 53% bulbs (29/55) still kept triploidy and the most cells of root tips contained 30 chromosomes. 40% bulbs (22/55) displayed aneuploidy and the most cells of its root tips contained 10-50 chromosomes. 7.2% bulbs (4/55) displayed hexaploidy and contained 60 chromosomes. After three months growing, the cells of root tips containing aneuploidy chromosomes disappeared, and the bulbs became triploidy. The chromosomes of 4 hexaploidy bulbs did not changed during three checks. The aneuploidy cells of Chinese narcissus after treated by colchicine were discussed for its origin and disappearing.